work on raster tools

lightningbeam-ui/lightningbeam-core/src/actions/mod.rs

@@ -34,6 +34,7 @@ pub mod group_layers;
 pub mod raster_stroke;
 pub mod raster_fill;
 pub mod move_layer;
+pub mod set_fill_paint;
 
 pub use add_clip_instance::AddClipInstanceAction;
 pub use add_effect::AddEffectAction;
@@ -66,3 +67,4 @@ pub use group_layers::GroupLayersAction;
 pub use raster_stroke::RasterStrokeAction;
 pub use raster_fill::RasterFillAction;
 pub use move_layer::MoveLayerAction;
+pub use set_fill_paint::SetFillPaintAction;

lightningbeam-ui/lightningbeam-core/src/actions/set_fill_paint.rs

@@ -0,0 +1,127 @@
+//! Action that changes the fill of one or more DCEL faces.
+//!
+//! Handles both solid-colour and gradient fills, clearing the other type so they
+//! don't coexist on a face.
+
+use crate::action::Action;
+use crate::dcel::FaceId;
+use crate::document::Document;
+use crate::gradient::ShapeGradient;
+use crate::layer::AnyLayer;
+use crate::shape::ShapeColor;
+use uuid::Uuid;
+
+/// Snapshot of one face's fill state (both types) for undo.
+#[derive(Clone)]
+struct OldFill {
+    face_id:  FaceId,
+    color:    Option<ShapeColor>,
+    gradient: Option<ShapeGradient>,
+}
+
+/// Action that sets a solid-colour *or* gradient fill on a set of faces,
+/// clearing the other fill type.
+pub struct SetFillPaintAction {
+    layer_id:     Uuid,
+    time:         f64,
+    face_ids:     Vec<FaceId>,
+    new_color:    Option<ShapeColor>,
+    new_gradient: Option<ShapeGradient>,
+    old_fills:    Vec<OldFill>,
+    description:  &'static str,
+}
+
+impl SetFillPaintAction {
+    /// Set a solid fill (clears any gradient on the same faces).
+    pub fn solid(
+        layer_id: Uuid,
+        time: f64,
+        face_ids: Vec<FaceId>,
+        color: Option<ShapeColor>,
+    ) -> Self {
+        Self {
+            layer_id,
+            time,
+            face_ids,
+            new_color:    color,
+            new_gradient: None,
+            old_fills:    Vec::new(),
+            description:  "Set fill colour",
+        }
+    }
+
+    /// Set a gradient fill (clears any solid colour on the same faces).
+    pub fn gradient(
+        layer_id: Uuid,
+        time: f64,
+        face_ids: Vec<FaceId>,
+        gradient: Option<ShapeGradient>,
+    ) -> Self {
+        Self {
+            layer_id,
+            time,
+            face_ids,
+            new_color:    None,
+            new_gradient: gradient,
+            old_fills:    Vec::new(),
+            description:  "Set gradient fill",
+        }
+    }
+
+    fn get_dcel_mut<'a>(
+        document: &'a mut Document,
+        layer_id: &Uuid,
+        time: f64,
+    ) -> Result<&'a mut crate::dcel::Dcel, String> {
+        let layer = document
+            .get_layer_mut(layer_id)
+            .ok_or_else(|| format!("Layer {} not found", layer_id))?;
+        match layer {
+            AnyLayer::Vector(vl) => vl
+                .dcel_at_time_mut(time)
+                .ok_or_else(|| format!("No keyframe at time {}", time)),
+            _ => Err("Not a vector layer".to_string()),
+        }
+    }
+}
+
+impl Action for SetFillPaintAction {
+    fn execute(&mut self, document: &mut Document) -> Result<(), String> {
+        let dcel = Self::get_dcel_mut(document, &self.layer_id, self.time)?;
+        self.old_fills.clear();
+
+        for &fid in &self.face_ids {
+            let face = dcel.face(fid);
+            self.old_fills.push(OldFill {
+                face_id:  fid,
+                color:    face.fill_color,
+                gradient: face.gradient_fill.clone(),
+            });
+
+            let face_mut = dcel.face_mut(fid);
+            // Setting a gradient clears solid colour and vice-versa.
+            if self.new_gradient.is_some() || self.new_color.is_none() {
+                face_mut.fill_color    = self.new_color;
+                face_mut.gradient_fill = self.new_gradient.clone();
+            } else {
+                face_mut.fill_color    = self.new_color;
+                face_mut.gradient_fill = None;
+            }
+        }
+        Ok(())
+    }
+
+    fn rollback(&mut self, document: &mut Document) -> Result<(), String> {
+        let dcel = Self::get_dcel_mut(document, &self.layer_id, self.time)?;
+        for old in &self.old_fills {
+            let face = dcel.face_mut(old.face_id);
+            face.fill_color    = old.color;
+            face.gradient_fill = old.gradient.clone();
+        }
+        Ok(())
+    }
+
+    fn description(&self) -> String {
+        self.description.to_string()
+    }
+}

lightningbeam-ui/lightningbeam-core/src/dcel2/mod.rs

@@ -114,6 +114,8 @@ pub struct Face {
     pub image_fill: Option<uuid::Uuid>,
     pub fill_rule: FillRule,
     #[serde(default)]
+    pub gradient_fill: Option<crate::gradient::ShapeGradient>,
+    #[serde(default)]
     pub deleted: bool,
 }
 
@@ -241,6 +243,7 @@ impl Dcel {
             fill_color: None,
             image_fill: None,
             fill_rule: FillRule::NonZero,
+            gradient_fill: None,
             deleted: false,
         };
         let debug_recorder = if std::env::var("DAW_DCEL_RECORD").is_ok() {
@@ -372,6 +375,7 @@ impl Dcel {
             fill_color: None,
             image_fill: None,
             fill_rule: FillRule::NonZero,
+            gradient_fill: None,
             deleted: false,
         };
         if let Some(idx) = self.free_faces.pop() {

lightningbeam-ui/lightningbeam-core/src/gradient.rs

@@ -0,0 +1,178 @@
+//! Gradient types for vector and raster fills.
+
+use crate::shape::ShapeColor;
+use kurbo::Point;
+use serde::{Deserialize, Serialize};
+use vello::peniko::{self, Brush, Extend, Gradient};
+
+// ── Stop ────────────────────────────────────────────────────────────────────
+
+/// One colour stop in a gradient.
+#[derive(Clone, Copy, Debug, PartialEq, Serialize, Deserialize)]
+pub struct GradientStop {
+    /// Normalised position in [0.0, 1.0].
+    pub position: f32,
+    pub color: ShapeColor,
+}
+
+// ── Kind / Extend ────────────────────────────────────────────────────────────
+
+/// Whether the gradient transitions along a line or radiates from a point.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, Default)]
+pub enum GradientType {
+    #[default]
+    Linear,
+    Radial,
+}
+
+/// Behaviour outside the gradient's natural [0, 1] range.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, Default)]
+pub enum GradientExtend {
+    /// Clamp to edge colour (default).
+    #[default]
+    Pad,
+    /// Mirror the gradient.
+    Reflect,
+    /// Repeat the gradient.
+    Repeat,
+}
+
+impl From<GradientExtend> for Extend {
+    fn from(e: GradientExtend) -> Self {
+        match e {
+            GradientExtend::Pad     => Extend::Pad,
+            GradientExtend::Reflect => Extend::Reflect,
+            GradientExtend::Repeat  => Extend::Repeat,
+        }
+    }
+}
+
+// ── ShapeGradient ────────────────────────────────────────────────────────────
+
+/// A serialisable gradient description.
+///
+/// Stops are kept sorted by position (ascending).  There are always ≥ 2 stops.
+///
+/// *Rendering*: call [`to_peniko_brush`](ShapeGradient::to_peniko_brush) with
+/// explicit start/end canvas-space points.  For vector faces the caller derives
+/// the points from the bounding box + `angle`; for the raster tool the caller
+/// uses the drag start/end directly.
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+pub struct ShapeGradient {
+    pub kind:   GradientType,
+    /// Colour stops, sorted by position.
+    pub stops:  Vec<GradientStop>,
+    /// Angle in degrees for Linear (0 = left→right, 90 = top→bottom).
+    /// Ignored for Radial.
+    pub angle:  f32,
+    pub extend: GradientExtend,
+}
+
+impl Default for ShapeGradient {
+    fn default() -> Self {
+        Self {
+            kind:   GradientType::Linear,
+            stops:  vec![
+                GradientStop { position: 0.0, color: ShapeColor::rgba(0, 0, 0, 255) },
+                GradientStop { position: 1.0, color: ShapeColor::rgba(0, 0, 0, 0) },
+            ],
+            angle:  0.0,
+            extend: GradientExtend::Pad,
+        }
+    }
+}
+
+impl ShapeGradient {
+    // ── CPU evaluation ───────────────────────────────────────────────────────
+
+    /// Sample RGBA at `t ∈ [0,1]` by linear interpolation between adjacent stops.
+    /// Stops must be sorted ascending by position.
+    pub fn eval(&self, t: f32) -> [u8; 4] {
+        let t = t.clamp(0.0, 1.0);
+        if self.stops.is_empty() {
+            return [0, 0, 0, 0];
+        }
+        if self.stops.len() == 1 {
+            let c = self.stops[0].color;
+            return [c.r, c.g, c.b, c.a];
+        }
+        // Find first stop with position > t
+        let i = self.stops.partition_point(|s| s.position <= t);
+        if i == 0 {
+            let c = self.stops[0].color;
+            return [c.r, c.g, c.b, c.a];
+        }
+        if i >= self.stops.len() {
+            let c = self.stops.last().unwrap().color;
+            return [c.r, c.g, c.b, c.a];
+        }
+        let s0 = self.stops[i - 1];
+        let s1 = self.stops[i];
+        let span = s1.position - s0.position;
+        let f = if span <= 0.0 { 0.0 } else { (t - s0.position) / span };
+        fn lerp(a: u8, b: u8, f: f32) -> u8 {
+            (a as f32 + (b as f32 - a as f32) * f).round().clamp(0.0, 255.0) as u8
+        }
+        [
+            lerp(s0.color.r, s1.color.r, f),
+            lerp(s0.color.g, s1.color.g, f),
+            lerp(s0.color.b, s1.color.b, f),
+            lerp(s0.color.a, s1.color.a, f),
+        ]
+    }
+
+    /// Apply `extend` mode to a raw t value, returning t ∈ [0,1].
+    pub fn apply_extend(&self, t_raw: f32) -> f32 {
+        match self.extend {
+            GradientExtend::Pad => t_raw.clamp(0.0, 1.0),
+            GradientExtend::Repeat => {
+                let t = t_raw.rem_euclid(1.0);
+                if t < 0.0 { t + 1.0 } else { t }
+            }
+            GradientExtend::Reflect => {
+                let t = t_raw.rem_euclid(2.0).abs();
+                if t > 1.0 { 2.0 - t } else { t }
+            }
+        }
+    }
+
+    // ── GPU / peniko rendering ───────────────────────────────────────────────
+
+    /// Build a `peniko::Brush` from explicit start/end canvas-coordinate points.
+    ///
+    /// `opacity` in [0,1] is multiplied into all stop alphas.
+    pub fn to_peniko_brush(&self, start: Point, end: Point, opacity: f32) -> Brush {
+        // Convert stops to peniko tuples.
+        let peniko_stops: Vec<(f32, peniko::Color)> = self.stops.iter().map(|s| {
+            let a_scaled = (s.color.a as f32 * opacity).round().clamp(0.0, 255.0) as u8;
+            let col = peniko::Color::from_rgba8(s.color.r, s.color.g, s.color.b, a_scaled);
+            (s.position, col)
+        }).collect();
+
+        let extend: Extend = self.extend.into();
+
+        match self.kind {
+            GradientType::Linear => {
+                Brush::Gradient(
+                    Gradient::new_linear(start, end)
+                        .with_extend(extend)
+                        .with_stops(peniko_stops.as_slice()),
+                )
+            }
+            GradientType::Radial => {
+                let mid = Point::new(
+                    (start.x + end.x) * 0.5,
+                    (start.y + end.y) * 0.5,
+                );
+                let dx = end.x - start.x;
+                let dy = end.y - start.y;
+                let radius = ((dx * dx + dy * dy).sqrt() * 0.5) as f32;
+                Brush::Gradient(
+                    Gradient::new_radial(mid, radius)
+                        .with_extend(extend)
+                        .with_stops(peniko_stops.as_slice()),
+                )
+            }
+        }
+    }
+}

lightningbeam-ui/lightningbeam-core/src/lib.rs

@@ -53,6 +53,7 @@ pub mod raster_layer;
 pub mod brush_settings;
 pub mod brush_engine;
 pub mod raster_draw;
+pub mod gradient;
 
 #[cfg(debug_assertions)]
 pub mod test_mode;

lightningbeam-ui/lightningbeam-core/src/raster_layer.rs

@@ -113,8 +113,14 @@ pub struct RasterKeyframe {
     /// and encoded back to PNG on save.  An empty Vec means the canvas is blank (transparent).
     #[serde(skip)]
     pub raw_pixels: Vec<u8>,
+    /// Set to `true` whenever `raw_pixels` changes so the GPU texture cache can re-upload.
+    /// Always `true` after load; cleared by the renderer after uploading.
+    #[serde(skip, default = "default_true")]
+    pub texture_dirty: bool,
 }
 
+fn default_true() -> bool { true }
+
 impl RasterKeyframe {
     /// Returns true when the pixel buffer has been initialised (non-blank).
     pub fn has_pixels(&self) -> bool {

lightningbeam-ui/lightningbeam-core/src/renderer.rs

@@ -923,7 +923,25 @@ fn render_video_layer(
     }
 }
 
-/// Render a vector layer with all its clip instances and shape instances
+/// Compute start/end canvas points for a linear gradient across a bounding box.
+///
+/// The axis is centred on the bbox midpoint and oriented at `angle_deg` degrees
+/// (0 = left→right, 90 = top→bottom).  The axis extends ± half the bbox diagonal
+/// so the gradient covers the entire shape regardless of angle.
+fn gradient_bbox_endpoints(angle_deg: f32, bbox: kurbo::Rect) -> (kurbo::Point, kurbo::Point) {
+    let cx = bbox.center().x;
+    let cy = bbox.center().y;
+    let dx = bbox.width();
+    let dy = bbox.height();
+    // Use half the diagonal so the full gradient fits at any angle.
+    let half_len = (dx * dx + dy * dy).sqrt() * 0.5;
+    let rad = (angle_deg as f64).to_radians();
+    let (sin, cos) = (rad.sin(), rad.cos());
+    let start = kurbo::Point::new(cx - cos * half_len, cy - sin * half_len);
+    let end   = kurbo::Point::new(cx + cos * half_len, cy + sin * half_len);
+    (start, end)
+}
+
 /// Render a DCEL to a Vello scene.
 ///
 /// Walks faces for fills and edges for strokes.
@@ -942,7 +960,7 @@ pub fn render_dcel(
         if face.deleted || i == 0 {
             continue; // Skip unbounded face and deleted faces
         }
-        if face.fill_color.is_none() && face.image_fill.is_none() {
+        if face.fill_color.is_none() && face.image_fill.is_none() && face.gradient_fill.is_none() {
             continue; // No fill to render
         }
 
@@ -963,7 +981,19 @@ pub fn render_dcel(
             }
         }
 
-        // Color fill
+        // Gradient fill (takes priority over solid colour fill)
+        if !filled {
+            if let Some(ref grad) = face.gradient_fill {
+                use kurbo::{Point, Rect};
+                let bbox: Rect = vello::kurbo::Shape::bounding_box(&path);
+                let (start, end) = gradient_bbox_endpoints(grad.angle, bbox);
+                let brush = grad.to_peniko_brush(start, end, opacity_f32);
+                scene.fill(fill_rule, base_transform, &brush, None, &path);
+                filled = true;
+            }
+        }
+
+        // Solid colour fill
         if !filled {
             if let Some(fill_color) = &face.fill_color {
                 let alpha = ((fill_color.a as f32 / 255.0) * opacity_f32 * 255.0) as u8;

lightningbeam-ui/lightningbeam-editor/src/gpu_brush.rs

@@ -290,6 +290,491 @@ impl RasterTransformPipeline {
 }
 
 // ---------------------------------------------------------------------------
+// Displacement buffer (Warp / Liquify)
+// ---------------------------------------------------------------------------
+
+/// Per-pixel displacement map stored as a GPU buffer of `vec2f` values.
+///
+/// Each entry `disp[y * width + x]` stores `(dx, dy)` in canvas pixels.
+/// Used by both the Warp tool (bilinear grid warp) and the Liquify tool
+/// (brush-based freeform displacement).
+pub struct DisplacementBuffer {
+    pub buf:    wgpu::Buffer,
+    pub width:  u32,
+    pub height: u32,
+}
+
+// ---------------------------------------------------------------------------
+// Warp-apply pipeline
+// ---------------------------------------------------------------------------
+
+/// CPU-side parameters uniform for `warp_apply.wgsl`.
+/// Must match the `Params` struct in the shader (32 bytes, 16-byte aligned).
+/// grid_cols == 0 → per-pixel displacement buffer mode (Liquify).
+/// grid_cols  > 0 → control-point grid mode (Warp); disp[] has grid_cols*grid_rows entries.
+#[repr(C)]
+#[derive(Clone, Copy, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct WarpApplyParams {
+    pub src_w:     u32,
+    pub src_h:     u32,
+    pub dst_w:     u32,
+    pub dst_h:     u32,
+    pub grid_cols: u32,
+    pub grid_rows: u32,
+    pub _pad0:     u32,
+    pub _pad1:     u32,
+}
+
+/// Compute pipeline that reads a displacement buffer + source texture → warped output.
+/// Shared by the Warp tool and the Liquify tool's preview/commit pass.
+struct WarpApplyPipeline {
+    pipeline:  wgpu::ComputePipeline,
+    bg_layout: wgpu::BindGroupLayout,
+}
+
+impl WarpApplyPipeline {
+    fn new(device: &wgpu::Device) -> Self {
+        let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
+            label:  Some("warp_apply_shader"),
+            source: wgpu::ShaderSource::Wgsl(
+                include_str!("panes/shaders/warp_apply.wgsl").into(),
+            ),
+        });
+
+        let bg_layout = device.create_bind_group_layout(
+            &wgpu::BindGroupLayoutDescriptor {
+                label: Some("warp_apply_bgl"),
+                entries: &[
+                    // 0: params uniform
+                    wgpu::BindGroupLayoutEntry {
+                        binding: 0,
+                        visibility: wgpu::ShaderStages::COMPUTE,
+                        ty: wgpu::BindingType::Buffer {
+                            ty: wgpu::BufferBindingType::Uniform,
+                            has_dynamic_offset: false,
+                            min_binding_size: None,
+                        },
+                        count: None,
+                    },
+                    // 1: source texture (anchor canvas, sampled)
+                    wgpu::BindGroupLayoutEntry {
+                        binding: 1,
+                        visibility: wgpu::ShaderStages::COMPUTE,
+                        ty: wgpu::BindingType::Texture {
+                            sample_type:    wgpu::TextureSampleType::Float { filterable: true },
+                            view_dimension: wgpu::TextureViewDimension::D2,
+                            multisampled:   false,
+                        },
+                        count: None,
+                    },
+                    // 2: displacement buffer (read-only storage)
+                    wgpu::BindGroupLayoutEntry {
+                        binding: 2,
+                        visibility: wgpu::ShaderStages::COMPUTE,
+                        ty: wgpu::BindingType::Buffer {
+                            ty: wgpu::BufferBindingType::Storage { read_only: true },
+                            has_dynamic_offset: false,
+                            min_binding_size: None,
+                        },
+                        count: None,
+                    },
+                    // 3: destination texture (display canvas, write-only storage)
+                    wgpu::BindGroupLayoutEntry {
+                        binding: 3,
+                        visibility: wgpu::ShaderStages::COMPUTE,
+                        ty: wgpu::BindingType::StorageTexture {
+                            access:         wgpu::StorageTextureAccess::WriteOnly,
+                            format:         wgpu::TextureFormat::Rgba8Unorm,
+                            view_dimension: wgpu::TextureViewDimension::D2,
+                        },
+                        count: None,
+                    },
+                ],
+            },
+        );
+
+        let pipeline_layout = device.create_pipeline_layout(
+            &wgpu::PipelineLayoutDescriptor {
+                label:                Some("warp_apply_pl"),
+                bind_group_layouts:   &[&bg_layout],
+                push_constant_ranges: &[],
+            },
+        );
+
+        let pipeline = device.create_compute_pipeline(
+            &wgpu::ComputePipelineDescriptor {
+                label:   Some("warp_apply_pipeline"),
+                layout:  Some(&pipeline_layout),
+                module:  &shader,
+                entry_point: Some("main"),
+                compilation_options: Default::default(),
+                cache: None,
+            },
+        );
+
+        Self { pipeline, bg_layout }
+    }
+
+    fn apply(
+        &self,
+        device:   &wgpu::Device,
+        queue:    &wgpu::Queue,
+        src_view: &wgpu::TextureView,
+        disp_buf: &wgpu::Buffer,
+        dst_view: &wgpu::TextureView,
+        params:   WarpApplyParams,
+    ) {
+        use wgpu::util::DeviceExt;
+
+        let uniform_buf = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+            label:    Some("warp_apply_params"),
+            contents: bytemuck::bytes_of(&params),
+            usage:    wgpu::BufferUsages::UNIFORM,
+        });
+
+        let bg = device.create_bind_group(&wgpu::BindGroupDescriptor {
+            label:   Some("warp_apply_bg"),
+            layout:  &self.bg_layout,
+            entries: &[
+                wgpu::BindGroupEntry { binding: 0, resource: uniform_buf.as_entire_binding() },
+                wgpu::BindGroupEntry { binding: 1, resource: wgpu::BindingResource::TextureView(src_view) },
+                wgpu::BindGroupEntry { binding: 2, resource: disp_buf.as_entire_binding() },
+                wgpu::BindGroupEntry { binding: 3, resource: wgpu::BindingResource::TextureView(dst_view) },
+            ],
+        });
+
+        let mut encoder = device.create_command_encoder(
+            &wgpu::CommandEncoderDescriptor { label: Some("warp_apply_enc") },
+        );
+        {
+            let mut pass = encoder.begin_compute_pass(
+                &wgpu::ComputePassDescriptor { label: Some("warp_apply_pass"), timestamp_writes: None },
+            );
+            pass.set_pipeline(&self.pipeline);
+            pass.set_bind_group(0, &bg, &[]);
+            pass.dispatch_workgroups(params.dst_w.div_ceil(8), params.dst_h.div_ceil(8), 1);
+        }
+        queue.submit(Some(encoder.finish()));
+    }
+}
+
+// ---------------------------------------------------------------------------
+// Liquify-brush pipeline
+// ---------------------------------------------------------------------------
+
+/// CPU-side parameters uniform for `liquify_brush.wgsl`.
+/// Must match the `Params` struct in the shader (48 bytes, 16-byte aligned).
+#[repr(C)]
+#[derive(Clone, Copy, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct LiquifyBrushParams {
+    pub cx:       f32,
+    pub cy:       f32,
+    pub radius:   f32,
+    pub strength: f32,
+    pub dx:       f32,
+    pub dy:       f32,
+    pub mode:     u32,
+    pub map_w:    u32,
+    pub map_h:    u32,
+    pub _pad0:    u32,
+    pub _pad1:    u32,
+    pub _pad2:    u32,
+}
+
+/// Compute pipeline that updates a displacement map from a single brush step.
+struct LiquifyBrushPipeline {
+    pipeline:  wgpu::ComputePipeline,
+    bg_layout: wgpu::BindGroupLayout,
+}
+
+impl LiquifyBrushPipeline {
+    fn new(device: &wgpu::Device) -> Self {
+        let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
+            label:  Some("liquify_brush_shader"),
+            source: wgpu::ShaderSource::Wgsl(
+                include_str!("panes/shaders/liquify_brush.wgsl").into(),
+            ),
+        });
+
+        let bg_layout = device.create_bind_group_layout(
+            &wgpu::BindGroupLayoutDescriptor {
+                label: Some("liquify_brush_bgl"),
+                entries: &[
+                    // 0: params uniform
+                    wgpu::BindGroupLayoutEntry {
+                        binding: 0,
+                        visibility: wgpu::ShaderStages::COMPUTE,
+                        ty: wgpu::BindingType::Buffer {
+                            ty: wgpu::BufferBindingType::Uniform,
+                            has_dynamic_offset: false,
+                            min_binding_size: None,
+                        },
+                        count: None,
+                    },
+                    // 1: displacement buffer (read-write storage)
+                    wgpu::BindGroupLayoutEntry {
+                        binding: 1,
+                        visibility: wgpu::ShaderStages::COMPUTE,
+                        ty: wgpu::BindingType::Buffer {
+                            ty: wgpu::BufferBindingType::Storage { read_only: false },
+                            has_dynamic_offset: false,
+                            min_binding_size: None,
+                        },
+                        count: None,
+                    },
+                ],
+            },
+        );
+
+        let pipeline_layout = device.create_pipeline_layout(
+            &wgpu::PipelineLayoutDescriptor {
+                label:                Some("liquify_brush_pl"),
+                bind_group_layouts:   &[&bg_layout],
+                push_constant_ranges: &[],
+            },
+        );
+
+        let pipeline = device.create_compute_pipeline(
+            &wgpu::ComputePipelineDescriptor {
+                label:   Some("liquify_brush_pipeline"),
+                layout:  Some(&pipeline_layout),
+                module:  &shader,
+                entry_point: Some("main"),
+                compilation_options: Default::default(),
+                cache: None,
+            },
+        );
+
+        Self { pipeline, bg_layout }
+    }
+
+    fn update_displacement(
+        &self,
+        device:   &wgpu::Device,
+        queue:    &wgpu::Queue,
+        disp_buf: &wgpu::Buffer,
+        params:   LiquifyBrushParams,
+    ) {
+        use wgpu::util::DeviceExt;
+
+        let uniform_buf = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+            label:    Some("liquify_brush_params"),
+            contents: bytemuck::bytes_of(&params),
+            usage:    wgpu::BufferUsages::UNIFORM,
+        });
+
+        let bg = device.create_bind_group(&wgpu::BindGroupDescriptor {
+            label:   Some("liquify_brush_bg"),
+            layout:  &self.bg_layout,
+            entries: &[
+                wgpu::BindGroupEntry { binding: 0, resource: uniform_buf.as_entire_binding() },
+                wgpu::BindGroupEntry { binding: 1, resource: disp_buf.as_entire_binding() },
+            ],
+        });
+
+        let r = params.radius.ceil() as u32;
+        let wg_x = (2 * r + 1).div_ceil(8).max(1);
+        let wg_y = (2 * r + 1).div_ceil(8).max(1);
+
+        let mut encoder = device.create_command_encoder(
+            &wgpu::CommandEncoderDescriptor { label: Some("liquify_brush_enc") },
+        );
+        {
+            let mut pass = encoder.begin_compute_pass(
+                &wgpu::ComputePassDescriptor { label: Some("liquify_brush_pass"), timestamp_writes: None },
+            );
+            pass.set_pipeline(&self.pipeline);
+            pass.set_bind_group(0, &bg, &[]);
+            pass.dispatch_workgroups(wg_x, wg_y, 1);
+        }
+        queue.submit(Some(encoder.finish()));
+    }
+}
+
+// ---------------------------------------------------------------------------
+// ---------------------------------------------------------------------------
+// Gradient-fill pipeline
+// ---------------------------------------------------------------------------
+
+/// One gradient stop on the GPU side.  Colors are linear straight-alpha [0..1].
+/// Must be 32 bytes (8 × f32) to match `GradientStop` in `gradient_fill.wgsl`.
+#[repr(C)]
+#[derive(Clone, Copy, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct GpuGradientStop {
+    pub position: f32,
+    pub r: f32,
+    pub g: f32,
+    pub b: f32,
+    pub a: f32,
+    pub _pad: [f32; 3],
+}
+
+impl GpuGradientStop {
+    /// Construct from sRGB u8 bytes (as stored in `ShapeColor`).
+    /// RGB is converted to linear; alpha is kept linear (not gamma-encoded).
+    pub fn from_srgb_u8(position: f32, r: u8, g: u8, b: u8, a: u8) -> Self {
+        Self {
+            position,
+            r: srgb_to_linear(r as f32 / 255.0),
+            g: srgb_to_linear(g as f32 / 255.0),
+            b: srgb_to_linear(b as f32 / 255.0),
+            a: a as f32 / 255.0,
+            _pad: [0.0; 3],
+        }
+    }
+}
+
+/// CPU-side parameters uniform for `gradient_fill.wgsl`.
+/// Must be 48 bytes (12 × u32/f32), 16-byte aligned.
+#[repr(C)]
+#[derive(Clone, Copy, bytemuck::Pod, bytemuck::Zeroable)]
+struct GradientFillParams {
+    canvas_w:    u32,
+    canvas_h:    u32,
+    start_x:     f32,
+    start_y:     f32,
+    end_x:       f32,
+    end_y:       f32,
+    opacity:     f32,
+    extend_mode: u32,  // 0 = Pad, 1 = Reflect, 2 = Repeat
+    num_stops:   u32,
+    kind:        u32,  // 0 = Linear, 1 = Radial
+    _pad1:       u32,
+    _pad2:       u32,
+}
+
+/// Compute pipeline: composites a gradient over an anchor canvas → display canvas.
+struct GradientFillPipeline {
+    pipeline:  wgpu::ComputePipeline,
+    bg_layout: wgpu::BindGroupLayout,
+}
+
+impl GradientFillPipeline {
+    fn new(device: &wgpu::Device) -> Self {
+        let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
+            label:  Some("gradient_fill_shader"),
+            source: wgpu::ShaderSource::Wgsl(
+                include_str!("panes/shaders/gradient_fill.wgsl").into(),
+            ),
+        });
+
+        let bg_layout = device.create_bind_group_layout(
+            &wgpu::BindGroupLayoutDescriptor {
+                label: Some("gradient_fill_bgl"),
+                entries: &[
+                    // 0: params uniform
+                    wgpu::BindGroupLayoutEntry {
+                        binding: 0,
+                        visibility: wgpu::ShaderStages::COMPUTE,
+                        ty: wgpu::BindingType::Buffer {
+                            ty: wgpu::BufferBindingType::Uniform,
+                            has_dynamic_offset: false,
+                            min_binding_size: None,
+                        },
+                        count: None,
+                    },
+                    // 1: anchor (source) canvas
+                    wgpu::BindGroupLayoutEntry {
+                        binding: 1,
+                        visibility: wgpu::ShaderStages::COMPUTE,
+                        ty: wgpu::BindingType::Texture {
+                            sample_type:    wgpu::TextureSampleType::Float { filterable: false },
+                            view_dimension: wgpu::TextureViewDimension::D2,
+                            multisampled:   false,
+                        },
+                        count: None,
+                    },
+                    // 2: gradient stops (read-only storage buffer)
+                    wgpu::BindGroupLayoutEntry {
+                        binding: 2,
+                        visibility: wgpu::ShaderStages::COMPUTE,
+                        ty: wgpu::BindingType::Buffer {
+                            ty: wgpu::BufferBindingType::Storage { read_only: true },
+                            has_dynamic_offset: false,
+                            min_binding_size: None,
+                        },
+                        count: None,
+                    },
+                    // 3: display (destination) canvas — write-only storage texture
+                    wgpu::BindGroupLayoutEntry {
+                        binding: 3,
+                        visibility: wgpu::ShaderStages::COMPUTE,
+                        ty: wgpu::BindingType::StorageTexture {
+                            access:         wgpu::StorageTextureAccess::WriteOnly,
+                            format:         wgpu::TextureFormat::Rgba8Unorm,
+                            view_dimension: wgpu::TextureViewDimension::D2,
+                        },
+                        count: None,
+                    },
+                ],
+            },
+        );
+
+        let pipeline_layout = device.create_pipeline_layout(
+            &wgpu::PipelineLayoutDescriptor {
+                label:                Some("gradient_fill_pl"),
+                bind_group_layouts:   &[&bg_layout],
+                push_constant_ranges: &[],
+            },
+        );
+
+        let pipeline = device.create_compute_pipeline(
+            &wgpu::ComputePipelineDescriptor {
+                label:               Some("gradient_fill_pipeline"),
+                layout:              Some(&pipeline_layout),
+                module:              &shader,
+                entry_point:         Some("main"),
+                compilation_options: Default::default(),
+                cache:               None,
+            },
+        );
+
+        Self { pipeline, bg_layout }
+    }
+
+    fn apply(
+        &self,
+        device:    &wgpu::Device,
+        queue:     &wgpu::Queue,
+        src_view:  &wgpu::TextureView,
+        stops_buf: &wgpu::Buffer,
+        dst_view:  &wgpu::TextureView,
+        params:    GradientFillParams,
+    ) {
+        use wgpu::util::DeviceExt;
+
+        let uniform_buf = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+            label:    Some("gradient_fill_params"),
+            contents: bytemuck::bytes_of(&params),
+            usage:    wgpu::BufferUsages::UNIFORM,
+        });
+
+        let bg = device.create_bind_group(&wgpu::BindGroupDescriptor {
+            label:   Some("gradient_fill_bg"),
+            layout:  &self.bg_layout,
+            entries: &[
+                wgpu::BindGroupEntry { binding: 0, resource: uniform_buf.as_entire_binding() },
+                wgpu::BindGroupEntry { binding: 1, resource: wgpu::BindingResource::TextureView(src_view) },
+                wgpu::BindGroupEntry { binding: 2, resource: stops_buf.as_entire_binding() },
+                wgpu::BindGroupEntry { binding: 3, resource: wgpu::BindingResource::TextureView(dst_view) },
+            ],
+        });
+
+        let mut encoder = device.create_command_encoder(
+            &wgpu::CommandEncoderDescriptor { label: Some("gradient_fill_enc") },
+        );
+        {
+            let mut pass = encoder.begin_compute_pass(
+                &wgpu::ComputePassDescriptor { label: Some("gradient_fill_pass"), timestamp_writes: None },
+            );
+            pass.set_pipeline(&self.pipeline);
+            pass.set_bind_group(0, &bg, &[]);
+            pass.dispatch_workgroups(params.canvas_w.div_ceil(8), params.canvas_h.div_ceil(8), 1);
+        }
+        queue.submit(Some(encoder.finish()));
+    }
+}
+
 // GpuBrushEngine
 // ---------------------------------------------------------------------------
 
@@ -301,8 +786,18 @@ pub struct GpuBrushEngine {
     /// Lazily created on first raster transform use.
     transform_pipeline: Option<RasterTransformPipeline>,
 
+    /// Lazily created on first warp/liquify use.
+    warp_apply_pipeline:    Option<WarpApplyPipeline>,
+    /// Lazily created on first liquify brush use.
+    liquify_brush_pipeline: Option<LiquifyBrushPipeline>,
+    /// Lazily created on first gradient fill use.
+    gradient_fill_pipeline: Option<GradientFillPipeline>,
+
     /// Canvas texture pairs keyed by keyframe UUID.
     pub canvases: HashMap<Uuid, CanvasPair>,
+
+    /// Displacement map buffers keyed by a caller-supplied UUID.
+    pub displacement_bufs: HashMap<Uuid, DisplacementBuffer>,
 }
 
 /// CPU-side parameters uniform for the compute shader.
@@ -404,8 +899,12 @@ impl GpuBrushEngine {
         Self {
             compute_pipeline,
             compute_bg_layout,
-            transform_pipeline: None,
+            transform_pipeline:     None,
-            canvases: HashMap::new(),
+            warp_apply_pipeline:    None,
+            liquify_brush_pipeline: None,
+            gradient_fill_pipeline: None,
+            canvases:           HashMap::new(),
+            displacement_bufs:  HashMap::new(),
         }
     }
 
@@ -803,6 +1302,211 @@ impl GpuBrushEngine {
             }
         }
     }
+
+    // -----------------------------------------------------------------------
+    // Displacement buffer management
+    // -----------------------------------------------------------------------
+
+    /// Create a zero-initialised displacement buffer of `width × height` vec2f entries.
+    /// Returns the UUID under which it is stored.
+    pub fn create_displacement_buf(
+        &mut self,
+        device: &wgpu::Device,
+        id:     Uuid,
+        width:  u32,
+        height: u32,
+    ) {
+        let byte_len = (width * height * 8) as u64; // 2 × f32 per pixel
+        let buf = device.create_buffer(&wgpu::BufferDescriptor {
+            label:              Some("displacement_buf"),
+            size:               byte_len,
+            usage:              wgpu::BufferUsages::STORAGE
+                              | wgpu::BufferUsages::COPY_DST
+                              | wgpu::BufferUsages::COPY_SRC,
+            mapped_at_creation: false,
+        });
+        self.displacement_bufs.insert(id, DisplacementBuffer { buf, width, height });
+    }
+
+    /// Overwrite the displacement buffer contents with the provided data.
+    pub fn upload_displacement_buf(
+        &self,
+        queue:    &wgpu::Queue,
+        id:       &Uuid,
+        data:     &[[f32; 2]],
+    ) {
+        if let Some(db) = self.displacement_bufs.get(id) {
+            queue.write_buffer(&db.buf, 0, bytemuck::cast_slice(data));
+        }
+    }
+
+    /// Zero out a displacement buffer (reset all displacements to (0,0)).
+    pub fn clear_displacement_buf(&self, queue: &wgpu::Queue, id: &Uuid) {
+        if let Some(db) = self.displacement_bufs.get(id) {
+            let zeros = vec![0u8; (db.width * db.height * 8) as usize];
+            queue.write_buffer(&db.buf, 0, &zeros);
+        }
+    }
+
+    /// Remove a displacement buffer (e.g. when the warp/liquify operation ends).
+    pub fn remove_displacement_buf(&mut self, id: &Uuid) {
+        self.displacement_bufs.remove(id);
+    }
+
+    // -----------------------------------------------------------------------
+    // Warp apply (shared by Warp and Liquify tools)
+    // -----------------------------------------------------------------------
+
+    /// Upload `disp_data` to the displacement buffer and then run the warp-apply
+    /// shader from `anchor_id` → `display_id`.  The display canvas is swapped after.
+    ///
+    /// If `disp_data` is `None` the buffer is not re-uploaded (used by Liquify which
+    /// updates the buffer in-place via `liquify_brush_step`).
+    /// Apply warp displacement to produce the display canvas.
+    ///
+    /// `disp_data`: if `Some`, upload this data to the displacement buffer before running.
+    /// `grid_cols/grid_rows`: if > 0, the disp buffer contains only that many vec2f entries
+    ///   (control-point grid mode).  The shader does bilinear interpolation per pixel.
+    ///   If 0, the buffer is a full per-pixel map (Liquify mode).
+    pub fn apply_warp(
+        &mut self,
+        device:     &wgpu::Device,
+        queue:      &wgpu::Queue,
+        anchor_id:  &Uuid,
+        disp_id:    &Uuid,
+        display_id: &Uuid,
+        disp_data:  Option<&[[f32; 2]]>,
+        grid_cols:  u32,
+        grid_rows:  u32,
+    ) {
+        // Upload new displacement data if provided.
+        if let Some(data) = disp_data {
+            if let Some(db) = self.displacement_bufs.get(disp_id) {
+                queue.write_buffer(&db.buf, 0, bytemuck::cast_slice(data));
+            }
+        }
+
+        let pipeline = self.warp_apply_pipeline
+            .get_or_insert_with(|| WarpApplyPipeline::new(device));
+
+        let dispatched = {
+            let anchor  = self.canvases.get(anchor_id);
+            let display = self.canvases.get(display_id);
+            let disp_b  = self.displacement_bufs.get(disp_id);
+            if let (Some(anchor), Some(display), Some(db)) = (anchor, display, disp_b) {
+                let params = WarpApplyParams {
+                    src_w: anchor.width,
+                    src_h: anchor.height,
+                    dst_w: display.width,
+                    dst_h: display.height,
+                    grid_cols,
+                    grid_rows,
+                    _pad0: 0,
+                    _pad1: 0,
+                };
+                pipeline.apply(device, queue, anchor.src_view(), &db.buf, display.dst_view(), params);
+                true
+            } else {
+                false
+            }
+        };
+
+        if dispatched {
+            if let Some(display) = self.canvases.get_mut(display_id) {
+                display.swap();
+            }
+        }
+    }
+
+    // -----------------------------------------------------------------------
+    // Liquify brush step
+    // -----------------------------------------------------------------------
+
+    // -----------------------------------------------------------------------
+    // Gradient fill
+    // -----------------------------------------------------------------------
+
+    /// Composite a gradient over the anchor canvas into the display canvas.
+    ///
+    /// - `anchor_id`:  canvas holding the original pixels (read-only each frame).
+    /// - `display_id`: canvas to write the gradient result into.
+    /// - `stops`:      gradient stops (linear straight-alpha, converted from sRGB by caller).
+    /// - `start`, `end`: gradient axis endpoints in canvas pixels.
+    /// - `opacity`:    overall tool opacity [0..1].
+    /// - `extend_mode`: 0 = Pad, 1 = Reflect, 2 = Repeat.
+    pub fn apply_gradient_fill(
+        &mut self,
+        device:      &wgpu::Device,
+        queue:       &wgpu::Queue,
+        anchor_id:   &Uuid,
+        display_id:  &Uuid,
+        stops:       &[GpuGradientStop],
+        start:       (f32, f32),
+        end:         (f32, f32),
+        opacity:     f32,
+        extend_mode: u32,
+        kind:        u32,
+    ) {
+        use wgpu::util::DeviceExt;
+
+        let pipeline = self.gradient_fill_pipeline
+            .get_or_insert_with(|| GradientFillPipeline::new(device));
+
+        // Build the stops storage buffer.
+        let stops_buf = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+            label:    Some("gradient_stops_buf"),
+            contents: bytemuck::cast_slice(stops),
+            usage:    wgpu::BufferUsages::STORAGE,
+        });
+
+        let dispatched = {
+            let anchor  = self.canvases.get(anchor_id);
+            let display = self.canvases.get(display_id);
+            if let (Some(anchor), Some(display)) = (anchor, display) {
+                let params = GradientFillParams {
+                    canvas_w:    anchor.width,
+                    canvas_h:    anchor.height,
+                    start_x:     start.0,
+                    start_y:     start.1,
+                    end_x:       end.0,
+                    end_y:       end.1,
+                    opacity,
+                    extend_mode,
+                    num_stops:   stops.len() as u32,
+                    kind,
+                    _pad1: 0, _pad2: 0,
+                };
+                pipeline.apply(device, queue, anchor.src_view(), &stops_buf, display.dst_view(), params);
+                true
+            } else {
+                false
+            }
+        };
+
+        if dispatched {
+            if let Some(display) = self.canvases.get_mut(display_id) {
+                display.swap();
+            }
+        }
+    }
+
+    /// Dispatch the liquify-brush compute shader to update the displacement map.
+    pub fn liquify_brush_step(
+        &mut self,
+        device:  &wgpu::Device,
+        queue:   &wgpu::Queue,
+        disp_id: &Uuid,
+        params:  LiquifyBrushParams,
+    ) {
+        if !self.displacement_bufs.contains_key(disp_id) { return; }
+
+        let pipeline = self.liquify_brush_pipeline
+            .get_or_insert_with(|| LiquifyBrushPipeline::new(device));
+
+        if let Some(db) = self.displacement_bufs.get(disp_id) {
+            pipeline.update_displacement(device, queue, &db.buf, params);
+        }
+    }
 }
 
 // ---------------------------------------------------------------------------

lightningbeam-ui/lightningbeam-editor/src/panes/gradient_editor.rs

@@ -0,0 +1,261 @@
+//! Gradient stop editor widget.
+//!
+//! Call [`gradient_stop_editor`] inside any egui layout; it returns `true` when
+//! `gradient` was modified.
+
+use eframe::egui::{self, Color32, DragValue, Painter, Rect, Sense, Stroke, Vec2};
+use lightningbeam_core::gradient::{GradientExtend, GradientStop, GradientType, ShapeGradient};
+use lightningbeam_core::shape::ShapeColor;
+
+// ── Public entry point ───────────────────────────────────────────────────────
+
+/// Render an inline gradient editor.
+///
+/// * `gradient`      – the gradient being edited (mutated in place).
+/// * `selected_stop` – index of the currently selected stop (persisted by caller).
+///
+/// Returns `true` if anything changed.
+pub fn gradient_stop_editor(
+    ui: &mut egui::Ui,
+    gradient: &mut ShapeGradient,
+    selected_stop: &mut Option<usize>,
+) -> bool {
+    let mut changed = false;
+
+    // ── Row 1: Kind + angle ───────────────────────────────────────────────
+    ui.horizontal(|ui| {
+        let was_linear = gradient.kind == GradientType::Linear;
+        if ui.selectable_label(was_linear,  "Linear").clicked() && !was_linear {
+            gradient.kind = GradientType::Linear;
+            changed = true;
+        }
+        if ui.selectable_label(!was_linear, "Radial").clicked() && was_linear {
+            gradient.kind = GradientType::Radial;
+            changed = true;
+        }
+        if gradient.kind == GradientType::Linear {
+            ui.add_space(8.0);
+            ui.label("Angle:");
+            if ui.add(
+                DragValue::new(&mut gradient.angle)
+                    .speed(1.0)
+                    .range(-360.0..=360.0)
+                    .suffix("°"),
+            ).changed() {
+                changed = true;
+            }
+        }
+    });
+
+    // ── Gradient bar + handles ────────────────────────────────────────────
+    let bar_height   = 22.0_f32;
+    let handle_h     = 14.0_f32;
+    let total_height = bar_height + handle_h + 4.0;
+    let avail_w      = ui.available_width();
+
+    let (bar_rect, bar_resp) = ui.allocate_exact_size(
+        Vec2::new(avail_w, total_height),
+        Sense::click(),
+    );
+    let painter = ui.painter_at(bar_rect);
+
+    let bar   = Rect::from_min_size(bar_rect.min, Vec2::new(avail_w, bar_height));
+    let track = Rect::from_min_size(
+        egui::pos2(bar_rect.min.x, bar_rect.min.y + bar_height + 2.0),
+        Vec2::new(avail_w, handle_h),
+    );
+
+    // Draw checkerboard background (transparent indicator).
+    draw_checker(&painter, bar);
+
+    // Draw gradient bar as N segments.
+    let seg = 128_usize;
+    for i in 0..seg {
+        let t0 = i as f32 / seg as f32;
+        let t1 = (i + 1) as f32 / seg as f32;
+        let t  = (t0 + t1) * 0.5;
+        let [r, g, b, a] = gradient.eval(t);
+        let col = Color32::from_rgba_unmultiplied(r, g, b, a);
+        let x0  = bar.min.x + t0 * bar.width();
+        let x1  = bar.min.x + t1 * bar.width();
+        let seg_rect = Rect::from_min_max(
+            egui::pos2(x0, bar.min.y),
+            egui::pos2(x1, bar.max.y),
+        );
+        painter.rect_filled(seg_rect, 0.0, col);
+    }
+    // Outline.
+    painter.rect_stroke(bar, 2.0, Stroke::new(1.0, Color32::from_gray(60)), eframe::egui::StrokeKind::Middle);
+
+    // Click on bar → add stop.
+    if bar_resp.clicked() {
+        if let Some(pos) = bar_resp.interact_pointer_pos() {
+            if bar.contains(pos) {
+                let t = ((pos.x - bar.min.x) / bar.width()).clamp(0.0, 1.0);
+                let [r, g, b, a] = gradient.eval(t);
+                gradient.stops.push(GradientStop {
+                    position: t,
+                    color:    ShapeColor::rgba(r, g, b, a),
+                });
+                gradient.stops.sort_by(|a, b| a.position.partial_cmp(&b.position).unwrap());
+                *selected_stop = gradient.stops.iter().position(|s| s.position == t);
+                changed = true;
+            }
+        }
+    }
+
+    // Draw stop handles.
+    // We need to detect drags per-handle, so allocate individual rects with the
+    // regular egui input model. To avoid borrow conflicts we collect interactions
+    // before mutating.
+    let handle_w  = 10.0_f32;
+    let n_stops   = gradient.stops.len();
+
+    let mut drag_idx:    Option<usize>  = None;
+    let mut drag_delta:  f32            = 0.0;
+    let mut click_idx:   Option<usize>  = None;
+
+    // To render handles after collecting, remember their rects.
+    let handle_rects: Vec<Rect> = (0..n_stops).map(|i| {
+        let cx = track.min.x + gradient.stops[i].position * track.width();
+        Rect::from_center_size(
+            egui::pos2(cx, track.center().y),
+            Vec2::new(handle_w, handle_h),
+        )
+    }).collect();
+
+    for (i, &h_rect) in handle_rects.iter().enumerate() {
+        let resp = ui.interact(h_rect, ui.id().with(("grad_handle", i)), Sense::click_and_drag());
+        if resp.dragged() {
+            drag_idx = Some(i);
+            drag_delta = resp.drag_delta().x / track.width();
+        }
+        if resp.clicked() {
+            click_idx = Some(i);
+        }
+    }
+
+    // Apply drag.
+    if let (Some(i), delta) = (drag_idx, drag_delta) {
+        if delta != 0.0 {
+            let new_pos = (gradient.stops[i].position + delta).clamp(0.0, 1.0);
+            gradient.stops[i].position = new_pos;
+            // Re-sort and track the moved stop.
+            gradient.stops.sort_by(|a, b| a.position.partial_cmp(&b.position).unwrap());
+            // Find new index of the moved stop (closest position match).
+            if let Some(ref mut sel) = *selected_stop {
+                // Re-find by position proximity.
+                *sel = gradient.stops.iter().enumerate()
+                    .min_by(|(_, a), (_, b)| {
+                        let pa = (a.position - (gradient.stops.get(i).map_or(0.0, |s| s.position))).abs();
+                        let pb = (b.position - (gradient.stops.get(i).map_or(0.0, |s| s.position))).abs();
+                        pa.partial_cmp(&pb).unwrap()
+                    })
+                    .map(|(idx, _)| idx)
+                    .unwrap_or(0);
+            }
+            changed = true;
+        }
+    }
+
+    if let Some(i) = click_idx {
+        *selected_stop = Some(i);
+    }
+
+    // Paint handles on top (after interaction so they visually react).
+    for (i, h_rect) in handle_rects.iter().enumerate() {
+        let col = ShapeColor_to_Color32(gradient.stops[i].color);
+        let is_selected = *selected_stop == Some(i);
+
+        // Draw a downward-pointing triangle.
+        let cx = h_rect.center().x;
+        let top = h_rect.min.y;
+        let bot = h_rect.max.y;
+        let hw  = h_rect.width() * 0.5;
+        let tri = vec![
+            egui::pos2(cx,       bot),
+            egui::pos2(cx - hw,  top),
+            egui::pos2(cx + hw,  top),
+        ];
+        painter.add(egui::Shape::convex_polygon(
+            tri,
+            col,
+            Stroke::new(if is_selected { 2.0 } else { 1.0 },
+                        if is_selected { Color32::WHITE } else { Color32::from_gray(100) }),
+        ));
+    }
+
+    // ── Selected stop detail ──────────────────────────────────────────────
+    if let Some(i) = *selected_stop {
+        if i < gradient.stops.len() {
+            ui.separator();
+            ui.horizontal(|ui| {
+                let stop = &mut gradient.stops[i];
+                let mut rgba = [stop.color.r, stop.color.g, stop.color.b, stop.color.a];
+                if ui.color_edit_button_srgba_unmultiplied(&mut rgba).changed() {
+                    stop.color = ShapeColor::rgba(rgba[0], rgba[1], rgba[2], rgba[3]);
+                    changed = true;
+                }
+                ui.label("Position:");
+                if ui.add(
+                    DragValue::new(&mut stop.position)
+                        .speed(0.005)
+                        .range(0.0..=1.0),
+                ).changed() {
+                    gradient.stops.sort_by(|a, b| a.position.partial_cmp(&b.position).unwrap());
+                    changed = true;
+                }
+                let can_remove = gradient.stops.len() > 2;
+                if ui.add_enabled(can_remove, egui::Button::new("− Remove")).clicked() {
+                    gradient.stops.remove(i);
+                    *selected_stop = None;
+                    changed = true;
+                }
+            });
+        } else {
+            *selected_stop = None;
+        }
+    }
+
+    // ── Extend mode ───────────────────────────────────────────────────────
+    ui.horizontal(|ui| {
+        ui.label("Extend:");
+        if ui.selectable_label(gradient.extend == GradientExtend::Pad,     "Pad").clicked() {
+            gradient.extend = GradientExtend::Pad;     changed = true;
+        }
+        if ui.selectable_label(gradient.extend == GradientExtend::Reflect,  "Reflect").clicked() {
+            gradient.extend = GradientExtend::Reflect;  changed = true;
+        }
+        if ui.selectable_label(gradient.extend == GradientExtend::Repeat,   "Repeat").clicked() {
+            gradient.extend = GradientExtend::Repeat;   changed = true;
+        }
+    });
+
+    changed
+}
+
+// ── Helpers ──────────────────────────────────────────────────────────────────
+
+fn ShapeColor_to_Color32(c: ShapeColor) -> Color32 {
+    Color32::from_rgba_unmultiplied(c.r, c.g, c.b, c.a)
+}
+
+/// Draw a small grey/white checkerboard inside `rect`.
+fn draw_checker(painter: &Painter, rect: Rect) {
+    let cell = 6.0_f32;
+    let cols = ((rect.width()  / cell).ceil() as u32).max(1);
+    let rows = ((rect.height() / cell).ceil() as u32).max(1);
+    for row in 0..rows {
+        for col in 0..cols {
+            let light = (row + col) % 2 == 0;
+            let col32 = if light { Color32::from_gray(200) } else { Color32::from_gray(140) };
+            let x = rect.min.x + col as f32 * cell;
+            let y = rect.min.y + row as f32 * cell;
+            let r = Rect::from_min_size(
+                egui::pos2(x, y),
+                Vec2::splat(cell),
+            ).intersect(rect);
+            painter.rect_filled(r, 0.0, col32);
+        }
+    }
+}

lightningbeam-ui/lightningbeam-editor/src/panes/infopanel.rs

@@ -12,12 +12,14 @@
 
 use eframe::egui::{self, DragValue, Ui};
 use lightningbeam_core::brush_settings::{bundled_brushes, BrushSettings};
-use lightningbeam_core::actions::{SetDocumentPropertiesAction, SetShapePropertiesAction};
+use lightningbeam_core::actions::{SetDocumentPropertiesAction, SetShapePropertiesAction, SetFillPaintAction};
+use lightningbeam_core::gradient::ShapeGradient;
 use lightningbeam_core::layer::{AnyLayer, LayerTrait};
 use lightningbeam_core::selection::FocusSelection;
 use lightningbeam_core::shape::ShapeColor;
 use lightningbeam_core::tool::{SimplifyMode, Tool};
 use super::{NodePath, PaneRenderer, SharedPaneState};
+use super::gradient_editor::gradient_stop_editor;
 use uuid::Uuid;
 
 /// Info panel pane state
@@ -36,6 +38,10 @@ pub struct InfopanelPane {
     eraser_picker_expanded: bool,
     /// Cached preview textures, one per preset (populated lazily).
     brush_preview_textures: Vec<egui::TextureHandle>,
+    /// Selected stop index for gradient editor in shape section.
+    selected_shape_gradient_stop: Option<usize>,
+    /// Selected stop index for gradient editor in tool section (gradient tool).
+    selected_tool_gradient_stop: Option<usize>,
 }
 
 impl InfopanelPane {
@@ -50,6 +56,8 @@ impl InfopanelPane {
             selected_eraser_preset: default_eraser_idx,
             eraser_picker_expanded: false,
             brush_preview_textures: Vec::new(),
+            selected_shape_gradient_stop: None,
+            selected_tool_gradient_stop: None,
         }
     }
 }
@@ -65,6 +73,8 @@ struct SelectionInfo {
 
     // Shape property values (None = mixed)
     fill_color: Option<Option<ShapeColor>>,
+    /// None = mixed across selection; Some(None) = no gradient; Some(Some(g)) = all same gradient
+    fill_gradient: Option<Option<ShapeGradient>>,
     stroke_color: Option<Option<ShapeColor>>,
     stroke_width: Option<f64>,
 }
@@ -76,6 +86,7 @@ impl Default for SelectionInfo {
             dcel_count: 0,
             layer_id: None,
             fill_color: None,
+            fill_gradient: None,
             stroke_color: None,
             stroke_width: None,
         }
@@ -138,21 +149,32 @@ impl InfopanelPane {
                         // Gather fill properties from selected faces
                         let mut first_fill_color: Option<Option<ShapeColor>> = None;
                         let mut fill_color_mixed = false;
+                        let mut first_fill_gradient: Option<Option<ShapeGradient>> = None;
+                        let mut fill_gradient_mixed = false;
 
                         for &fid in shared.selection.selected_faces() {
                             let face = dcel.face(fid);
                             let fc = face.fill_color;
+                            let fg = face.gradient_fill.clone();
 
                             match first_fill_color {
                                 None => first_fill_color = Some(fc),
                                 Some(prev) if prev != fc => fill_color_mixed = true,
                                 _ => {}
                             }
+                            match &first_fill_gradient {
+                                None => first_fill_gradient = Some(fg),
+                                Some(prev) if *prev != fg => fill_gradient_mixed = true,
+                                _ => {}
+                            }
                         }
 
                         if !fill_color_mixed {
                             info.fill_color = first_fill_color;
                         }
+                        if !fill_gradient_mixed {
+                            info.fill_gradient = first_fill_gradient;
+                        }
                     }
                 }
             }
@@ -191,6 +213,7 @@ impl InfopanelPane {
             || is_raster_select || is_raster_shape || matches!(
             tool,
             Tool::PaintBucket | Tool::RegionSelect | Tool::MagicWand | Tool::QuickSelect
+            | Tool::Warp | Tool::Liquify | Tool::Gradient
         );
 
         if !has_options {
@@ -414,6 +437,62 @@ impl InfopanelPane {
                         });
                     }
 
+                    Tool::Warp => {
+                        ui.horizontal(|ui| {
+                            ui.label("Grid:");
+                            let cols = shared.raster_settings.warp_grid_cols;
+                            let rows = shared.raster_settings.warp_grid_rows;
+                            for (label, c, r) in [("3×3", 3u32, 3u32), ("4×4", 4, 4), ("5×5", 5, 5), ("8×8", 8, 8)] {
+                                let selected = cols == c && rows == r;
+                                if ui.selectable_label(selected, label).clicked() {
+                                    shared.raster_settings.warp_grid_cols = c;
+                                    shared.raster_settings.warp_grid_rows = r;
+                                }
+                            }
+                        });
+                        ui.small("Enter to commit · Escape to cancel");
+                    }
+
+                    Tool::Liquify => {
+                        use crate::tools::LiquifyMode;
+                        ui.horizontal(|ui| {
+                            ui.label("Mode:");
+                            for (label, mode) in [
+                                ("Push",        LiquifyMode::Push),
+                                ("Pucker",       LiquifyMode::Pucker),
+                                ("Bloat",        LiquifyMode::Bloat),
+                                ("Smooth",       LiquifyMode::Smooth),
+                                ("Reconstruct",  LiquifyMode::Reconstruct),
+                            ] {
+                                let selected = shared.raster_settings.liquify_mode == mode;
+                                if ui.selectable_label(selected, label).clicked() {
+                                    shared.raster_settings.liquify_mode = mode;
+                                }
+                            }
+                        });
+                        ui.horizontal(|ui| {
+                            ui.label("Radius:");
+                            ui.add(
+                                egui::Slider::new(
+                                    &mut shared.raster_settings.liquify_radius,
+                                    5.0_f32..=500.0,
+                                )
+                                .step_by(1.0),
+                            );
+                        });
+                        ui.horizontal(|ui| {
+                            ui.label("Strength:");
+                            ui.add(
+                                egui::Slider::new(
+                                    &mut shared.raster_settings.liquify_strength,
+                                    0.01_f32..=1.0,
+                                )
+                                .step_by(0.01),
+                            );
+                        });
+                        ui.small("Enter to commit · Escape to cancel");
+                    }
+
                     Tool::Polygon => {
                         // Number of sides
                         ui.horizontal(|ui| {
@@ -461,6 +540,22 @@ impl InfopanelPane {
                         });
                     }
 
+                    Tool::Gradient if active_is_raster => {
+                        ui.horizontal(|ui| {
+                            ui.label("Opacity:");
+                            ui.add(egui::Slider::new(
+                                &mut shared.raster_settings.gradient_opacity,
+                                0.0_f32..=1.0,
+                            ).custom_formatter(|v, _| format!("{:.0}%", v * 100.0)));
+                        });
+                        ui.add_space(4.0);
+                        gradient_stop_editor(
+                            ui,
+                            &mut shared.raster_settings.gradient,
+                            &mut self.selected_tool_gradient_stop,
+                        );
+                    }
+
                     _ => {}
                 }
 
@@ -680,28 +775,72 @@ impl InfopanelPane {
                 self.shape_section_open = true;
                 ui.add_space(4.0);
 
-                // Fill color
+                // Fill — determine current fill type
+                let has_gradient = matches!(&info.fill_gradient, Some(Some(_)));
+                let has_solid = matches!(&info.fill_color, Some(Some(_)));
+                let fill_is_none = matches!(&info.fill_color, Some(None))
+                    && matches!(&info.fill_gradient, Some(None));
+                let fill_mixed = info.fill_color.is_none() && info.fill_gradient.is_none();
+
+                // Fill type toggle row
                 ui.horizontal(|ui| {
                     ui.label("Fill:");
-                    match info.fill_color {
+                    if fill_mixed {
-                        Some(Some(color)) => {
+                        ui.label("--");
+                    } else {
+                        if ui.selectable_label(fill_is_none, "None").clicked() && !fill_is_none {
+                            let action = SetFillPaintAction::solid(
+                                layer_id, time, face_ids.clone(), None,
+                            );
+                            shared.pending_actions.push(Box::new(action));
+                        }
+                        if ui.selectable_label(has_solid || (!has_gradient && !fill_is_none), "Solid").clicked() && !has_solid {
+                            // Switch to solid: use existing color or default to black
+                            let color = info.fill_color.flatten()
+                                .unwrap_or(ShapeColor::rgba(0, 0, 0, 255));
+                            let action = SetFillPaintAction::solid(
+                                layer_id, time, face_ids.clone(), Some(color),
+                            );
+                            shared.pending_actions.push(Box::new(action));
+                        }
+                        if ui.selectable_label(has_gradient, "Gradient").clicked() && !has_gradient {
+                            let grad = info.fill_gradient.clone().flatten()
+                                .unwrap_or_default();
+                            let action = SetFillPaintAction::gradient(
+                                layer_id, time, face_ids.clone(), Some(grad),
+                            );
+                            shared.pending_actions.push(Box::new(action));
+                        }
+                    }
+                });
+
+                // Solid fill color editor
+                if !fill_mixed && has_solid {
+                    if let Some(Some(color)) = info.fill_color {
+                        ui.horizontal(|ui| {
                             let mut rgba = [color.r, color.g, color.b, color.a];
                             if ui.color_edit_button_srgba_unmultiplied(&mut rgba).changed() {
                                 let new_color = ShapeColor::rgba(rgba[0], rgba[1], rgba[2], rgba[3]);
-                                let action = SetShapePropertiesAction::set_fill_color(
+                                let action = SetFillPaintAction::solid(
                                     layer_id, time, face_ids.clone(), Some(new_color),
                                 );
                                 shared.pending_actions.push(Box::new(action));
                             }
-                        }
+                        });
-                        Some(None) => {
+                    }
-                            ui.label("None");
+                }
-                        }
+
-                        None => {
+                // Gradient fill editor
-                            ui.label("--");
+                if !fill_mixed && has_gradient {
+                    if let Some(Some(mut grad)) = info.fill_gradient.clone() {
+                        if gradient_stop_editor(ui, &mut grad, &mut self.selected_shape_gradient_stop) {
+                            let action = SetFillPaintAction::gradient(
+                                layer_id, time, face_ids.clone(), Some(grad),
+                            );
+                            shared.pending_actions.push(Box::new(action));
                         }
                     }
-                });
+                }
 
                 // Stroke color
                 ui.horizontal(|ui| {

lightningbeam-ui/lightningbeam-editor/src/panes/mod.rs

@@ -68,6 +68,7 @@ pub enum WebcamRecordCommand {
 
 pub mod toolbar;
 pub mod stage;
+pub mod gradient_editor;
 pub mod timeline;
 pub mod infopanel;
 pub mod outliner;

lightningbeam-ui/lightningbeam-editor/src/panes/shaders/gradient_fill.wgsl

@@ -0,0 +1,137 @@
+// GPU gradient fill shader.
+//
+// Reads the anchor canvas (before_pixels), composites a gradient over it, and
+// writes the result to the display canvas.  All color values in the canvas are
+// linear premultiplied RGBA.  The stop colors passed via `stops` are linear
+// straight-alpha [0..1] (sRGB→linear conversion is done on the CPU).
+//
+// Dispatch: ceil(canvas_w / 8) × ceil(canvas_h / 8) × 1
+
+struct Params {
+    canvas_w:    u32,
+    canvas_h:    u32,
+    start_x:     f32,
+    start_y:     f32,
+    end_x:       f32,
+    end_y:       f32,
+    opacity:     f32,
+    extend_mode: u32,  // 0 = Pad, 1 = Reflect, 2 = Repeat
+    num_stops:   u32,
+    kind:        u32,  // 0 = Linear, 1 = Radial
+    _pad1:       u32,
+    _pad2:       u32,
+}
+
+// 32 bytes per stop (8 × f32), matching `GpuGradientStop` on the Rust side.
+struct GradientStop {
+    position: f32,
+    r:        f32,  // linear [0..1], straight-alpha
+    g:        f32,
+    b:        f32,
+    a:        f32,
+    _pad0:    f32,
+    _pad1:    f32,
+    _pad2:    f32,
+}
+
+@group(0) @binding(0) var<uniform>       params: Params;
+@group(0) @binding(1) var                src:    texture_2d<f32>;
+@group(0) @binding(2) var<storage, read> stops:  array<GradientStop>;
+@group(0) @binding(3) var                dst:    texture_storage_2d<rgba8unorm, write>;
+
+fn apply_extend(t: f32) -> f32 {
+    if params.extend_mode == 0u {
+        // Pad: clamp to [0, 1]
+        return clamp(t, 0.0, 1.0);
+    } else if params.extend_mode == 1u {
+        // Reflect: 0→1→0→1→...
+        let t_abs = abs(t);
+        let period = floor(t_abs);
+        let frac = t_abs - period;
+        if (u32(period) & 1u) == 0u {
+            return frac;
+        } else {
+            return 1.0 - frac;
+        }
+    } else {
+        // Repeat: tile [0, 1)
+        return t - floor(t);
+    }
+}
+
+fn eval_gradient(t: f32) -> vec4<f32> {
+    let n = params.num_stops;
+    if n == 0u { return vec4<f32>(0.0); }
+
+    let s0 = stops[0];
+    if t <= s0.position {
+        return vec4<f32>(s0.r, s0.g, s0.b, s0.a);
+    }
+
+    let sn = stops[n - 1u];
+    if t >= sn.position {
+        return vec4<f32>(sn.r, sn.g, sn.b, sn.a);
+    }
+
+    for (var i = 0u; i < n - 1u; i++) {
+        let sa = stops[i];
+        let sb = stops[i + 1u];
+        if t >= sa.position && t <= sb.position {
+            let span = sb.position - sa.position;
+            let f = select(0.0, (t - sa.position) / span, span > 0.0001);
+            return mix(
+                vec4<f32>(sa.r, sa.g, sa.b, sa.a),
+                vec4<f32>(sb.r, sb.g, sb.b, sb.a),
+                f,
+            );
+        }
+    }
+
+    return vec4<f32>(sn.r, sn.g, sn.b, sn.a);
+}
+
+@compute @workgroup_size(8, 8)
+fn main(@builtin(global_invocation_id) gid: vec3<u32>) {
+    if gid.x >= params.canvas_w || gid.y >= params.canvas_h { return; }
+
+    // Anchor pixel (linear premultiplied RGBA).
+    let src_px = textureLoad(src, vec2<i32>(i32(gid.x), i32(gid.y)), 0);
+
+    let dx = params.end_x - params.start_x;
+    let dy = params.end_y - params.start_y;
+    let px = f32(gid.x) + 0.5;
+    let py = f32(gid.y) + 0.5;
+
+    var t_raw: f32 = 0.0;
+    if params.kind == 1u {
+        // Radial: center at start point, radius = |end-start|.
+        let radius = sqrt(dx * dx + dy * dy);
+        if radius >= 0.5 {
+            let pdx = px - params.start_x;
+            let pdy = py - params.start_y;
+            t_raw = sqrt(pdx * pdx + pdy * pdy) / radius;
+        }
+    } else {
+        // Linear: project pixel centre onto gradient axis (start → end).
+        let len2 = dx * dx + dy * dy;
+        if len2 >= 1.0 {
+            let fx = px - params.start_x;
+            let fy = py - params.start_y;
+            t_raw = (fx * dx + fy * dy) / len2;
+        }
+    }
+
+    let t    = apply_extend(t_raw);
+    let grad = eval_gradient(t);  // straight-alpha linear RGBA
+
+    // Effective alpha: gradient alpha × tool opacity.
+    let a = grad.a * params.opacity;
+
+    // Alpha-over composite.
+    // src_px.rgb is premultiplied (= straight_rgb * src_a).
+    // Output is also premultiplied.
+    let out_a   = a + src_px.a * (1.0 - a);
+    let out_rgb = grad.rgb * a + src_px.rgb * (1.0 - a);
+
+    textureStore(dst, vec2<i32>(i32(gid.x), i32(gid.y)), vec4<f32>(out_rgb, out_a));
+}

lightningbeam-ui/lightningbeam-editor/src/panes/shaders/liquify_brush.wgsl

@@ -0,0 +1,92 @@
+// GPU liquify-brush shader.
+//
+// Updates a per-pixel displacement map (array of vec2f) for one brush step.
+// Each pixel within the brush radius receives a displacement contribution
+// weighted by a Gaussian falloff.
+//
+// Modes:
+//   0 = Push        — displace in brush-drag direction (dx, dy)
+//   1 = Pucker      — pull toward brush center
+//   2 = Bloat       — push away from brush center
+//   3 = Smooth      — blend toward average of 4 cardinal neighbours
+//   4 = Reconstruct — blend toward zero (gradually undo)
+//
+// Dispatch: ceil((2*radius+1) / 8) × ceil((2*radius+1) / 8) × 1
+// The CPU clips invocation IDs to the valid map range.
+
+struct Params {
+    cx:       f32,   // brush center x (canvas pixels)
+    cy:       f32,   // brush center y
+    radius:   f32,   // brush radius (canvas pixels)
+    strength: f32,   // effect strength [0..1]
+    dx:       f32,   // push direction x (normalised by caller, Push mode only)
+    dy:       f32,   // push direction y
+    mode:     u32,   // 0=Push 1=Pucker 2=Bloat 3=Smooth 4=Reconstruct
+    map_w:    u32,
+    map_h:    u32,
+    _pad0:    u32,
+    _pad1:    u32,
+}
+
+@group(0) @binding(0) var<uniform>             params: Params;
+@group(0) @binding(1) var<storage, read_write> disp:   array<vec2f>;
+
+@compute @workgroup_size(8, 8)
+fn main(@builtin(global_invocation_id) gid: vec3<u32>) {
+    // Offset invocation into the brush bounding box so gid(0,0) = (cx-r, cy-r).
+    let base_x = floor(params.cx - params.radius);
+    let base_y = floor(params.cy - params.radius);
+    let px = base_x + f32(gid.x);
+    let py = base_y + f32(gid.y);
+
+    // Clip to displacement map bounds.
+    if px < 0.0 || py < 0.0 { return; }
+    let map_x = u32(px);
+    let map_y = u32(py);
+    if map_x >= params.map_w || map_y >= params.map_h { return; }
+
+    let ddx = px - params.cx;
+    let ddy = py - params.cy;
+    let dist2 = ddx * ddx + ddy * ddy;
+    let r2    = params.radius * params.radius;
+
+    if dist2 > r2 { return; }
+
+    // Gaussian influence: 1 at center, ~0.01 at edge (sigma = radius/2.15)
+    let influence = params.strength * exp(-dist2 / (r2 * 0.2));
+
+    let idx = map_y * params.map_w + map_x;
+    var d = disp[idx];
+
+    switch params.mode {
+        case 0u: { // Push
+            d = d + vec2f(params.dx, params.dy) * influence * params.radius;
+        }
+        case 1u: { // Pucker — toward center
+            let len = sqrt(dist2) + 0.0001;
+            d = d + vec2f(-ddx / len, -ddy / len) * influence * params.radius;
+        }
+        case 2u: { // Bloat — away from center
+            let len = sqrt(dist2) + 0.0001;
+            d = d + vec2f(ddx / len, ddy / len) * influence * params.radius;
+        }
+        case 3u: { // Smooth — blend toward average of 4 neighbours
+            let xi = i32(map_x);
+            let yi = i32(map_y);
+            let w  = i32(params.map_w);
+            let h  = i32(params.map_h);
+            let l  = disp[u32(clamp(yi,     0, h-1)) * params.map_w + u32(clamp(xi - 1, 0, w-1))];
+            let r  = disp[u32(clamp(yi,     0, h-1)) * params.map_w + u32(clamp(xi + 1, 0, w-1))];
+            let u  = disp[u32(clamp(yi - 1, 0, h-1)) * params.map_w + u32(clamp(xi,     0, w-1))];
+            let dn = disp[u32(clamp(yi + 1, 0, h-1)) * params.map_w + u32(clamp(xi,     0, w-1))];
+            let avg = (l + r + u + dn) * 0.25;
+            d = mix(d, avg, influence * 0.5);
+        }
+        case 4u: { // Reconstruct — blend toward zero
+            d = mix(d, vec2f(0.0), influence * 0.5);
+        }
+        default: {}
+    }
+
+    disp[idx] = d;
+}

lightningbeam-ui/lightningbeam-editor/src/panes/shaders/warp_apply.wgsl

@@ -0,0 +1,103 @@
+// GPU warp-apply shader.
+//
+// Two modes selected by grid_cols / grid_rows:
+//
+//   grid_cols == 0  (Liquify / per-pixel mode)
+//     disp[] is a full canvas-sized array<vec2f>.  Each pixel reads its own entry.
+//
+//   grid_cols > 0   (Warp control-point mode)
+//     disp[] contains only grid_cols * grid_rows vec2f displacements (one per
+//     control point).  The shader bilinearly interpolates them so the CPU never
+//     needs to build or upload the full per-pixel buffer.
+//
+// Dispatch: ceil(dst_w / 8) × ceil(dst_h / 8) × 1
+
+struct Params {
+    src_w:     u32,
+    src_h:     u32,
+    dst_w:     u32,
+    dst_h:     u32,
+    grid_cols: u32,   // 0 = per-pixel mode
+    grid_rows: u32,
+    _pad0:     u32,
+    _pad1:     u32,
+}
+
+@group(0) @binding(0) var<uniform>       params: Params;
+@group(0) @binding(1) var                src:    texture_2d<f32>;
+@group(0) @binding(2) var<storage, read> disp:   array<vec2f>;
+@group(0) @binding(3) var                dst:    texture_storage_2d<rgba8unorm, write>;
+
+// Manual bilinear sample with clamp-to-edge (textureSample forbidden in compute shaders).
+fn bilinear_sample(px: f32, py: f32) -> vec4<f32> {
+    let sw = i32(params.src_w);
+    let sh = i32(params.src_h);
+
+    let ix = i32(floor(px - 0.5));
+    let iy = i32(floor(py - 0.5));
+    let fx = fract(px - 0.5);
+    let fy = fract(py - 0.5);
+
+    let x0 = clamp(ix,     0, sw - 1);
+    let x1 = clamp(ix + 1, 0, sw - 1);
+    let y0 = clamp(iy,     0, sh - 1);
+    let y1 = clamp(iy + 1, 0, sh - 1);
+
+    let s00 = textureLoad(src, vec2<i32>(x0, y0), 0);
+    let s10 = textureLoad(src, vec2<i32>(x1, y0), 0);
+    let s01 = textureLoad(src, vec2<i32>(x0, y1), 0);
+    let s11 = textureLoad(src, vec2<i32>(x1, y1), 0);
+
+    return mix(mix(s00, s10, fx), mix(s01, s11, fx), fy);
+}
+
+// Bilinearly interpolate the control-point displacement grid.
+fn grid_displacement(px: u32, py: u32) -> vec2f {
+    let cols = params.grid_cols;
+    let rows = params.grid_rows;
+
+    // Normalised position in grid space [0 .. cols-1] × [0 .. rows-1].
+    let gx = f32(px) / f32(params.dst_w  - 1u) * f32(cols - 1u);
+    let gy = f32(py) / f32(params.dst_h - 1u) * f32(rows - 1u);
+
+    let col0 = u32(floor(gx));
+    let row0 = u32(floor(gy));
+    let col1 = min(col0 + 1u, cols - 1u);
+    let row1 = min(row0 + 1u, rows - 1u);
+    let fx = gx - floor(gx);
+    let fy = gy - floor(gy);
+
+    let d00 = disp[row0 * cols + col0];
+    let d10 = disp[row0 * cols + col1];
+    let d01 = disp[row1 * cols + col0];
+    let d11 = disp[row1 * cols + col1];
+
+    return d00 * (1.0 - fx) * (1.0 - fy)
+         + d10 * fx          * (1.0 - fy)
+         + d01 * (1.0 - fx)  * fy
+         + d11 * fx          * fy;
+}
+
+@compute @workgroup_size(8, 8)
+fn main(@builtin(global_invocation_id) gid: vec3<u32>) {
+    if gid.x >= params.dst_w || gid.y >= params.dst_h { return; }
+
+    var d: vec2f;
+    if params.grid_cols > 0u {
+        d = grid_displacement(gid.x, gid.y);
+    } else {
+        d = disp[gid.y * params.dst_w + gid.x];
+    }
+
+    let sx = f32(gid.x) + d.x;
+    let sy = f32(gid.y) + d.y;
+
+    var color: vec4<f32>;
+    if sx < 0.0 || sy < 0.0 || sx >= f32(params.src_w) || sy >= f32(params.src_h) {
+        color = vec4<f32>(0.0);
+    } else {
+        color = bilinear_sample(sx + 0.5, sy + 0.5);
+    }
+
+    textureStore(dst, vec2<i32>(i32(gid.x), i32(gid.y)), color);
+}

lightningbeam-ui/lightningbeam-editor/src/tools/mod.rs

@@ -99,6 +99,39 @@ pub struct RasterToolSettings {
     // --- Marquee select shape ---
     /// Whether the rectangular select tool draws a rect or an ellipse.
     pub select_shape: SelectionShape,
+    // --- Warp ---
+    pub warp_grid_cols: u32,
+    pub warp_grid_rows: u32,
+    // --- Liquify ---
+    pub liquify_mode:     LiquifyMode,
+    pub liquify_radius:   f32,
+    pub liquify_strength: f32,
+    // --- Gradient ---
+    pub gradient: lightningbeam_core::gradient::ShapeGradient,
+    pub gradient_opacity: f32,
+}
+
+/// Brush mode for the Liquify tool.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
+pub enum LiquifyMode {
+    #[default]
+    Push,
+    Pucker,
+    Bloat,
+    Smooth,
+    Reconstruct,
+}
+
+impl LiquifyMode {
+    pub fn as_u32(self) -> u32 {
+        match self {
+            LiquifyMode::Push        => 0,
+            LiquifyMode::Pucker      => 1,
+            LiquifyMode::Bloat       => 2,
+            LiquifyMode::Smooth      => 3,
+            LiquifyMode::Reconstruct => 4,
+        }
+    }
 }
 
 /// Shape mode for the rectangular-select tool.
@@ -168,6 +201,13 @@ impl Default for RasterToolSettings {
             fill_threshold_mode: FillThresholdMode::Absolute,
             quick_select_radius: 20.0,
             select_shape: SelectionShape::Rect,
+            warp_grid_cols: 4,
+            warp_grid_rows: 4,
+            liquify_mode:     LiquifyMode::Push,
+            liquify_radius:   50.0,
+            liquify_strength: 0.5,
+            gradient:         lightningbeam_core::gradient::ShapeGradient::default(),
+            gradient_opacity: 1.0,
         }
     }
 }