egui/crates/epaint/src/tessellator.rs

2197 lines
76 KiB
Rust

//! Converts graphics primitives into textured triangles.
//!
//! This module converts lines, circles, text and more represented by [`Shape`]
//! into textured triangles represented by [`Mesh`].
#![allow(clippy::identity_op)]
use crate::texture_atlas::PreparedDisc;
use crate::{
color, emath, stroke, CircleShape, ClippedPrimitive, ClippedShape, Color32, CubicBezierShape,
EllipseShape, Mesh, PathShape, Primitive, QuadraticBezierShape, RectShape, Rounding, Shape,
Stroke, TextShape, TextureId, Vertex, WHITE_UV,
};
use emath::{pos2, remap, vec2, NumExt, Pos2, Rect, Rot2, Vec2};
use self::color::ColorMode;
use self::stroke::PathStroke;
// ----------------------------------------------------------------------------
#[allow(clippy::approx_constant)]
mod precomputed_vertices {
// fn main() {
// let n = 64;
// println!("pub const CIRCLE_{}: [Vec2; {}] = [", n, n+1);
// for i in 0..=n {
// let a = std::f64::consts::TAU * i as f64 / n as f64;
// println!(" vec2({:.06}, {:.06}),", a.cos(), a.sin());
// }
// println!("];")
// }
use emath::{vec2, Vec2};
pub const CIRCLE_8: [Vec2; 9] = [
vec2(1.000000, 0.000000),
vec2(0.707107, 0.707107),
vec2(0.000000, 1.000000),
vec2(-0.707107, 0.707107),
vec2(-1.000000, 0.000000),
vec2(-0.707107, -0.707107),
vec2(0.000000, -1.000000),
vec2(0.707107, -0.707107),
vec2(1.000000, 0.000000),
];
pub const CIRCLE_16: [Vec2; 17] = [
vec2(1.000000, 0.000000),
vec2(0.923880, 0.382683),
vec2(0.707107, 0.707107),
vec2(0.382683, 0.923880),
vec2(0.000000, 1.000000),
vec2(-0.382684, 0.923880),
vec2(-0.707107, 0.707107),
vec2(-0.923880, 0.382683),
vec2(-1.000000, 0.000000),
vec2(-0.923880, -0.382683),
vec2(-0.707107, -0.707107),
vec2(-0.382684, -0.923880),
vec2(0.000000, -1.000000),
vec2(0.382684, -0.923879),
vec2(0.707107, -0.707107),
vec2(0.923880, -0.382683),
vec2(1.000000, 0.000000),
];
pub const CIRCLE_32: [Vec2; 33] = [
vec2(1.000000, 0.000000),
vec2(0.980785, 0.195090),
vec2(0.923880, 0.382683),
vec2(0.831470, 0.555570),
vec2(0.707107, 0.707107),
vec2(0.555570, 0.831470),
vec2(0.382683, 0.923880),
vec2(0.195090, 0.980785),
vec2(0.000000, 1.000000),
vec2(-0.195090, 0.980785),
vec2(-0.382683, 0.923880),
vec2(-0.555570, 0.831470),
vec2(-0.707107, 0.707107),
vec2(-0.831470, 0.555570),
vec2(-0.923880, 0.382683),
vec2(-0.980785, 0.195090),
vec2(-1.000000, 0.000000),
vec2(-0.980785, -0.195090),
vec2(-0.923880, -0.382683),
vec2(-0.831470, -0.555570),
vec2(-0.707107, -0.707107),
vec2(-0.555570, -0.831470),
vec2(-0.382683, -0.923880),
vec2(-0.195090, -0.980785),
vec2(-0.000000, -1.000000),
vec2(0.195090, -0.980785),
vec2(0.382683, -0.923880),
vec2(0.555570, -0.831470),
vec2(0.707107, -0.707107),
vec2(0.831470, -0.555570),
vec2(0.923880, -0.382683),
vec2(0.980785, -0.195090),
vec2(1.000000, -0.000000),
];
pub const CIRCLE_64: [Vec2; 65] = [
vec2(1.000000, 0.000000),
vec2(0.995185, 0.098017),
vec2(0.980785, 0.195090),
vec2(0.956940, 0.290285),
vec2(0.923880, 0.382683),
vec2(0.881921, 0.471397),
vec2(0.831470, 0.555570),
vec2(0.773010, 0.634393),
vec2(0.707107, 0.707107),
vec2(0.634393, 0.773010),
vec2(0.555570, 0.831470),
vec2(0.471397, 0.881921),
vec2(0.382683, 0.923880),
vec2(0.290285, 0.956940),
vec2(0.195090, 0.980785),
vec2(0.098017, 0.995185),
vec2(0.000000, 1.000000),
vec2(-0.098017, 0.995185),
vec2(-0.195090, 0.980785),
vec2(-0.290285, 0.956940),
vec2(-0.382683, 0.923880),
vec2(-0.471397, 0.881921),
vec2(-0.555570, 0.831470),
vec2(-0.634393, 0.773010),
vec2(-0.707107, 0.707107),
vec2(-0.773010, 0.634393),
vec2(-0.831470, 0.555570),
vec2(-0.881921, 0.471397),
vec2(-0.923880, 0.382683),
vec2(-0.956940, 0.290285),
vec2(-0.980785, 0.195090),
vec2(-0.995185, 0.098017),
vec2(-1.000000, 0.000000),
vec2(-0.995185, -0.098017),
vec2(-0.980785, -0.195090),
vec2(-0.956940, -0.290285),
vec2(-0.923880, -0.382683),
vec2(-0.881921, -0.471397),
vec2(-0.831470, -0.555570),
vec2(-0.773010, -0.634393),
vec2(-0.707107, -0.707107),
vec2(-0.634393, -0.773010),
vec2(-0.555570, -0.831470),
vec2(-0.471397, -0.881921),
vec2(-0.382683, -0.923880),
vec2(-0.290285, -0.956940),
vec2(-0.195090, -0.980785),
vec2(-0.098017, -0.995185),
vec2(-0.000000, -1.000000),
vec2(0.098017, -0.995185),
vec2(0.195090, -0.980785),
vec2(0.290285, -0.956940),
vec2(0.382683, -0.923880),
vec2(0.471397, -0.881921),
vec2(0.555570, -0.831470),
vec2(0.634393, -0.773010),
vec2(0.707107, -0.707107),
vec2(0.773010, -0.634393),
vec2(0.831470, -0.555570),
vec2(0.881921, -0.471397),
vec2(0.923880, -0.382683),
vec2(0.956940, -0.290285),
vec2(0.980785, -0.195090),
vec2(0.995185, -0.098017),
vec2(1.000000, -0.000000),
];
pub const CIRCLE_128: [Vec2; 129] = [
vec2(1.000000, 0.000000),
vec2(0.998795, 0.049068),
vec2(0.995185, 0.098017),
vec2(0.989177, 0.146730),
vec2(0.980785, 0.195090),
vec2(0.970031, 0.242980),
vec2(0.956940, 0.290285),
vec2(0.941544, 0.336890),
vec2(0.923880, 0.382683),
vec2(0.903989, 0.427555),
vec2(0.881921, 0.471397),
vec2(0.857729, 0.514103),
vec2(0.831470, 0.555570),
vec2(0.803208, 0.595699),
vec2(0.773010, 0.634393),
vec2(0.740951, 0.671559),
vec2(0.707107, 0.707107),
vec2(0.671559, 0.740951),
vec2(0.634393, 0.773010),
vec2(0.595699, 0.803208),
vec2(0.555570, 0.831470),
vec2(0.514103, 0.857729),
vec2(0.471397, 0.881921),
vec2(0.427555, 0.903989),
vec2(0.382683, 0.923880),
vec2(0.336890, 0.941544),
vec2(0.290285, 0.956940),
vec2(0.242980, 0.970031),
vec2(0.195090, 0.980785),
vec2(0.146730, 0.989177),
vec2(0.098017, 0.995185),
vec2(0.049068, 0.998795),
vec2(0.000000, 1.000000),
vec2(-0.049068, 0.998795),
vec2(-0.098017, 0.995185),
vec2(-0.146730, 0.989177),
vec2(-0.195090, 0.980785),
vec2(-0.242980, 0.970031),
vec2(-0.290285, 0.956940),
vec2(-0.336890, 0.941544),
vec2(-0.382683, 0.923880),
vec2(-0.427555, 0.903989),
vec2(-0.471397, 0.881921),
vec2(-0.514103, 0.857729),
vec2(-0.555570, 0.831470),
vec2(-0.595699, 0.803208),
vec2(-0.634393, 0.773010),
vec2(-0.671559, 0.740951),
vec2(-0.707107, 0.707107),
vec2(-0.740951, 0.671559),
vec2(-0.773010, 0.634393),
vec2(-0.803208, 0.595699),
vec2(-0.831470, 0.555570),
vec2(-0.857729, 0.514103),
vec2(-0.881921, 0.471397),
vec2(-0.903989, 0.427555),
vec2(-0.923880, 0.382683),
vec2(-0.941544, 0.336890),
vec2(-0.956940, 0.290285),
vec2(-0.970031, 0.242980),
vec2(-0.980785, 0.195090),
vec2(-0.989177, 0.146730),
vec2(-0.995185, 0.098017),
vec2(-0.998795, 0.049068),
vec2(-1.000000, 0.000000),
vec2(-0.998795, -0.049068),
vec2(-0.995185, -0.098017),
vec2(-0.989177, -0.146730),
vec2(-0.980785, -0.195090),
vec2(-0.970031, -0.242980),
vec2(-0.956940, -0.290285),
vec2(-0.941544, -0.336890),
vec2(-0.923880, -0.382683),
vec2(-0.903989, -0.427555),
vec2(-0.881921, -0.471397),
vec2(-0.857729, -0.514103),
vec2(-0.831470, -0.555570),
vec2(-0.803208, -0.595699),
vec2(-0.773010, -0.634393),
vec2(-0.740951, -0.671559),
vec2(-0.707107, -0.707107),
vec2(-0.671559, -0.740951),
vec2(-0.634393, -0.773010),
vec2(-0.595699, -0.803208),
vec2(-0.555570, -0.831470),
vec2(-0.514103, -0.857729),
vec2(-0.471397, -0.881921),
vec2(-0.427555, -0.903989),
vec2(-0.382683, -0.923880),
vec2(-0.336890, -0.941544),
vec2(-0.290285, -0.956940),
vec2(-0.242980, -0.970031),
vec2(-0.195090, -0.980785),
vec2(-0.146730, -0.989177),
vec2(-0.098017, -0.995185),
vec2(-0.049068, -0.998795),
vec2(-0.000000, -1.000000),
vec2(0.049068, -0.998795),
vec2(0.098017, -0.995185),
vec2(0.146730, -0.989177),
vec2(0.195090, -0.980785),
vec2(0.242980, -0.970031),
vec2(0.290285, -0.956940),
vec2(0.336890, -0.941544),
vec2(0.382683, -0.923880),
vec2(0.427555, -0.903989),
vec2(0.471397, -0.881921),
vec2(0.514103, -0.857729),
vec2(0.555570, -0.831470),
vec2(0.595699, -0.803208),
vec2(0.634393, -0.773010),
vec2(0.671559, -0.740951),
vec2(0.707107, -0.707107),
vec2(0.740951, -0.671559),
vec2(0.773010, -0.634393),
vec2(0.803208, -0.595699),
vec2(0.831470, -0.555570),
vec2(0.857729, -0.514103),
vec2(0.881921, -0.471397),
vec2(0.903989, -0.427555),
vec2(0.923880, -0.382683),
vec2(0.941544, -0.336890),
vec2(0.956940, -0.290285),
vec2(0.970031, -0.242980),
vec2(0.980785, -0.195090),
vec2(0.989177, -0.146730),
vec2(0.995185, -0.098017),
vec2(0.998795, -0.049068),
vec2(1.000000, -0.000000),
];
}
// ----------------------------------------------------------------------------
#[derive(Clone, Copy, Debug, Default, PartialEq)]
struct PathPoint {
pos: Pos2,
/// For filled paths the normal is used for anti-aliasing (both strokes and filled areas).
///
/// For strokes the normal is also used for giving thickness to the path
/// (i.e. in what direction to expand).
///
/// The normal could be estimated by differences between successive points,
/// but that would be less accurate (and in some cases slower).
///
/// Normals are normally unit-length.
normal: Vec2,
}
/// A connected line (without thickness or gaps) which can be tessellated
/// to either to a stroke (with thickness) or a filled convex area.
/// Used as a scratch-pad during tessellation.
#[derive(Clone, Debug, Default)]
pub struct Path(Vec<PathPoint>);
impl Path {
#[inline(always)]
pub fn clear(&mut self) {
self.0.clear();
}
#[inline(always)]
pub fn reserve(&mut self, additional: usize) {
self.0.reserve(additional);
}
#[inline(always)]
pub fn add_point(&mut self, pos: Pos2, normal: Vec2) {
self.0.push(PathPoint { pos, normal });
}
pub fn add_circle(&mut self, center: Pos2, radius: f32) {
use precomputed_vertices::{CIRCLE_128, CIRCLE_16, CIRCLE_32, CIRCLE_64, CIRCLE_8};
// These cutoffs are based on a high-dpi display. TODO(emilk): use pixels_per_point here?
// same cutoffs as in add_circle_quadrant
if radius <= 2.0 {
self.0.extend(CIRCLE_8.iter().map(|&n| PathPoint {
pos: center + radius * n,
normal: n,
}));
} else if radius <= 5.0 {
self.0.extend(CIRCLE_16.iter().map(|&n| PathPoint {
pos: center + radius * n,
normal: n,
}));
} else if radius < 18.0 {
self.0.extend(CIRCLE_32.iter().map(|&n| PathPoint {
pos: center + radius * n,
normal: n,
}));
} else if radius < 50.0 {
self.0.extend(CIRCLE_64.iter().map(|&n| PathPoint {
pos: center + radius * n,
normal: n,
}));
} else {
self.0.extend(CIRCLE_128.iter().map(|&n| PathPoint {
pos: center + radius * n,
normal: n,
}));
}
}
pub fn add_line_segment(&mut self, points: [Pos2; 2]) {
self.reserve(2);
let normal = (points[1] - points[0]).normalized().rot90();
self.add_point(points[0], normal);
self.add_point(points[1], normal);
}
pub fn add_open_points(&mut self, points: &[Pos2]) {
let n = points.len();
assert!(n >= 2);
if n == 2 {
// Common case optimization:
self.add_line_segment([points[0], points[1]]);
} else {
self.reserve(n);
self.add_point(points[0], (points[1] - points[0]).normalized().rot90());
let mut n0 = (points[1] - points[0]).normalized().rot90();
for i in 1..n - 1 {
let mut n1 = (points[i + 1] - points[i]).normalized().rot90();
// Handle duplicated points (but not triplicated…):
if n0 == Vec2::ZERO {
n0 = n1;
} else if n1 == Vec2::ZERO {
n1 = n0;
}
let normal = (n0 + n1) / 2.0;
let length_sq = normal.length_sq();
let right_angle_length_sq = 0.5;
let sharper_than_a_right_angle = length_sq < right_angle_length_sq;
if sharper_than_a_right_angle {
// cut off the sharp corner
let center_normal = normal.normalized();
let n0c = (n0 + center_normal) / 2.0;
let n1c = (n1 + center_normal) / 2.0;
self.add_point(points[i], n0c / n0c.length_sq());
self.add_point(points[i], n1c / n1c.length_sq());
} else {
// miter join
self.add_point(points[i], normal / length_sq);
}
n0 = n1;
}
self.add_point(
points[n - 1],
(points[n - 1] - points[n - 2]).normalized().rot90(),
);
}
}
pub fn add_line_loop(&mut self, points: &[Pos2]) {
let n = points.len();
assert!(n >= 2);
self.reserve(n);
let mut n0 = (points[0] - points[n - 1]).normalized().rot90();
for i in 0..n {
let next_i = if i + 1 == n { 0 } else { i + 1 };
let mut n1 = (points[next_i] - points[i]).normalized().rot90();
// Handle duplicated points (but not triplicated…):
if n0 == Vec2::ZERO {
n0 = n1;
} else if n1 == Vec2::ZERO {
n1 = n0;
}
let normal = (n0 + n1) / 2.0;
let length_sq = normal.length_sq();
// We can't just cut off corners for filled shapes like this,
// because the feather will both expand and contract the corner along the provided normals
// to make sure it doesn't grow, and the shrinking will make the inner points cross each other.
//
// A better approach is to shrink the vertices in by half the feather-width here
// and then only expand during feathering.
//
// See https://github.com/emilk/egui/issues/1226
const CUT_OFF_SHARP_CORNERS: bool = false;
let right_angle_length_sq = 0.5;
let sharper_than_a_right_angle = length_sq < right_angle_length_sq;
if CUT_OFF_SHARP_CORNERS && sharper_than_a_right_angle {
// cut off the sharp corner
let center_normal = normal.normalized();
let n0c = (n0 + center_normal) / 2.0;
let n1c = (n1 + center_normal) / 2.0;
self.add_point(points[i], n0c / n0c.length_sq());
self.add_point(points[i], n1c / n1c.length_sq());
} else {
// miter join
self.add_point(points[i], normal / length_sq);
}
n0 = n1;
}
}
/// Open-ended.
pub fn stroke_open(&mut self, feathering: f32, stroke: &PathStroke, out: &mut Mesh) {
stroke_path(feathering, &mut self.0, PathType::Open, stroke, out);
}
/// A closed path (returning to the first point).
pub fn stroke_closed(&mut self, feathering: f32, stroke: &PathStroke, out: &mut Mesh) {
stroke_path(feathering, &mut self.0, PathType::Closed, stroke, out);
}
pub fn stroke(
&mut self,
feathering: f32,
path_type: PathType,
stroke: &PathStroke,
out: &mut Mesh,
) {
stroke_path(feathering, &mut self.0, path_type, stroke, out);
}
/// The path is taken to be closed (i.e. returning to the start again).
///
/// Calling this may reverse the vertices in the path if they are wrong winding order.
///
/// The preferred winding order is clockwise.
///
/// The stroke colors is used for color-correct feathering.
pub fn fill(&mut self, feathering: f32, color: Color32, stroke: &PathStroke, out: &mut Mesh) {
fill_closed_path(feathering, &mut self.0, color, stroke, out);
}
/// Like [`Self::fill`] but with texturing.
///
/// The `uv_from_pos` is called for each vertex position.
pub fn fill_with_uv(
&mut self,
feathering: f32,
color: Color32,
texture_id: TextureId,
uv_from_pos: impl Fn(Pos2) -> Pos2,
out: &mut Mesh,
) {
fill_closed_path_with_uv(feathering, &mut self.0, color, texture_id, uv_from_pos, out);
}
}
pub mod path {
//! Helpers for constructing paths
use crate::shape::Rounding;
use emath::{pos2, Pos2, Rect};
/// overwrites existing points
pub fn rounded_rectangle(path: &mut Vec<Pos2>, rect: Rect, rounding: Rounding) {
path.clear();
let min = rect.min;
let max = rect.max;
let r = clamp_rounding(rounding, rect);
if r == Rounding::ZERO {
path.reserve(4);
path.push(pos2(min.x, min.y)); // left top
path.push(pos2(max.x, min.y)); // right top
path.push(pos2(max.x, max.y)); // right bottom
path.push(pos2(min.x, max.y)); // left bottom
} else {
// We need to avoid duplicated vertices, because that leads to visual artifacts later.
// Duplicated vertices can happen when one side is all rounding, with no straight edge between.
let eps = f32::EPSILON * rect.size().max_elem();
add_circle_quadrant(path, pos2(max.x - r.se, max.y - r.se), r.se, 0.0); // south east
if rect.width() <= r.se + r.sw + eps {
path.pop(); // avoid duplicated vertex
}
add_circle_quadrant(path, pos2(min.x + r.sw, max.y - r.sw), r.sw, 1.0); // south west
if rect.height() <= r.sw + r.nw + eps {
path.pop(); // avoid duplicated vertex
}
add_circle_quadrant(path, pos2(min.x + r.nw, min.y + r.nw), r.nw, 2.0); // north west
if rect.width() <= r.nw + r.ne + eps {
path.pop(); // avoid duplicated vertex
}
add_circle_quadrant(path, pos2(max.x - r.ne, min.y + r.ne), r.ne, 3.0); // north east
if rect.height() <= r.ne + r.se + eps {
path.pop(); // avoid duplicated vertex
}
}
}
/// Add one quadrant of a circle
///
/// * quadrant 0: right bottom
/// * quadrant 1: left bottom
/// * quadrant 2: left top
/// * quadrant 3: right top
//
// Derivation:
//
// * angle 0 * TAU / 4 = right
// - quadrant 0: right bottom
// * angle 1 * TAU / 4 = bottom
// - quadrant 1: left bottom
// * angle 2 * TAU / 4 = left
// - quadrant 2: left top
// * angle 3 * TAU / 4 = top
// - quadrant 3: right top
// * angle 4 * TAU / 4 = right
pub fn add_circle_quadrant(path: &mut Vec<Pos2>, center: Pos2, radius: f32, quadrant: f32) {
use super::precomputed_vertices::{CIRCLE_128, CIRCLE_16, CIRCLE_32, CIRCLE_64, CIRCLE_8};
// These cutoffs are based on a high-dpi display. TODO(emilk): use pixels_per_point here?
// same cutoffs as in add_circle
if radius <= 0.0 {
path.push(center);
} else if radius <= 2.0 {
let offset = quadrant as usize * 2;
let quadrant_vertices = &CIRCLE_8[offset..=offset + 2];
path.extend(quadrant_vertices.iter().map(|&n| center + radius * n));
} else if radius <= 5.0 {
let offset = quadrant as usize * 4;
let quadrant_vertices = &CIRCLE_16[offset..=offset + 4];
path.extend(quadrant_vertices.iter().map(|&n| center + radius * n));
} else if radius < 18.0 {
let offset = quadrant as usize * 8;
let quadrant_vertices = &CIRCLE_32[offset..=offset + 8];
path.extend(quadrant_vertices.iter().map(|&n| center + radius * n));
} else if radius < 50.0 {
let offset = quadrant as usize * 16;
let quadrant_vertices = &CIRCLE_64[offset..=offset + 16];
path.extend(quadrant_vertices.iter().map(|&n| center + radius * n));
} else {
let offset = quadrant as usize * 32;
let quadrant_vertices = &CIRCLE_128[offset..=offset + 32];
path.extend(quadrant_vertices.iter().map(|&n| center + radius * n));
}
}
// Ensures the radius of each corner is within a valid range
fn clamp_rounding(rounding: Rounding, rect: Rect) -> Rounding {
let half_width = rect.width() * 0.5;
let half_height = rect.height() * 0.5;
let max_cr = half_width.min(half_height);
rounding.at_most(max_cr).at_least(0.0)
}
}
// ----------------------------------------------------------------------------
#[derive(Clone, Copy, PartialEq, Eq)]
pub enum PathType {
Open,
Closed,
}
/// Tessellation quality options
#[derive(Clone, Copy, Debug, PartialEq)]
#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
#[cfg_attr(feature = "serde", serde(default))]
pub struct TessellationOptions {
/// Use "feathering" to smooth out the edges of shapes as a form of anti-aliasing.
///
/// Feathering works by making each edge into a thin gradient into transparency.
/// The size of this edge is controlled by [`Self::feathering_size_in_pixels`].
///
/// This makes shapes appear smoother, but requires more triangles and is therefore slower.
///
/// This setting does not affect text.
///
/// Default: `true`.
pub feathering: bool,
/// The size of the feathering, in physical pixels.
///
/// The default, and suggested, value for this is `1.0`.
/// If you use a larger value, edges will appear blurry.
pub feathering_size_in_pixels: f32,
/// If `true` (default) cull certain primitives before tessellating them.
/// This likely makes
pub coarse_tessellation_culling: bool,
/// If `true`, small filled circled will be optimized by using pre-rasterized circled
/// from the font atlas.
pub prerasterized_discs: bool,
/// If `true` (default) align text to mesh grid.
/// This makes the text sharper on most platforms.
pub round_text_to_pixels: bool,
/// Output the clip rectangles to be painted.
pub debug_paint_clip_rects: bool,
/// Output the text-containing rectangles.
pub debug_paint_text_rects: bool,
/// If true, no clipping will be done.
pub debug_ignore_clip_rects: bool,
/// The maximum distance between the original curve and the flattened curve.
pub bezier_tolerance: f32,
/// The default value will be 1.0e-5, it will be used during float compare.
pub epsilon: f32,
/// If `rayon` feature is activated, should we parallelize tessellation?
pub parallel_tessellation: bool,
/// If `true`, invalid meshes will be silently ignored.
/// If `false`, invalid meshes will cause a panic.
///
/// The default is `false` to save performance.
pub validate_meshes: bool,
}
impl Default for TessellationOptions {
fn default() -> Self {
Self {
feathering: true,
feathering_size_in_pixels: 1.0,
coarse_tessellation_culling: true,
prerasterized_discs: true,
round_text_to_pixels: true,
debug_paint_text_rects: false,
debug_paint_clip_rects: false,
debug_ignore_clip_rects: false,
bezier_tolerance: 0.1,
epsilon: 1.0e-5,
parallel_tessellation: true,
validate_meshes: false,
}
}
}
fn cw_signed_area(path: &[PathPoint]) -> f64 {
if let Some(last) = path.last() {
let mut previous = last.pos;
let mut area = 0.0;
for p in path {
area += (previous.x * p.pos.y - p.pos.x * previous.y) as f64;
previous = p.pos;
}
area
} else {
0.0
}
}
/// Tessellate the given convex area into a polygon.
///
/// Calling this may reverse the vertices in the path if they are wrong winding order.
///
/// The preferred winding order is clockwise.
///
/// A stroke is required so that the fill's feathering can fade to the right color. You can pass `&PathStroke::NONE` if
/// this path won't be stroked.
fn fill_closed_path(
feathering: f32,
path: &mut [PathPoint],
color: Color32,
stroke: &PathStroke,
out: &mut Mesh,
) {
if color == Color32::TRANSPARENT {
return;
}
// TODO(juancampa): This bounding box is computed twice per shape: once here and another when tessellating the
// stroke, consider hoisting that logic to the tessellator/scratchpad.
let bbox = Rect::from_points(&path.iter().map(|p| p.pos).collect::<Vec<Pos2>>())
.expand((stroke.width / 2.0) + feathering);
let stroke_color = &stroke.color;
let get_stroke_color: Box<dyn Fn(Pos2) -> Color32> = match stroke_color {
ColorMode::Solid(col) => Box::new(|_pos: Pos2| *col),
ColorMode::UV(fun) => Box::new(|pos: Pos2| fun(bbox, pos)),
};
let n = path.len() as u32;
if feathering > 0.0 {
if cw_signed_area(path) < 0.0 {
// Wrong winding order - fix:
path.reverse();
for point in &mut *path {
point.normal = -point.normal;
}
}
out.reserve_triangles(3 * n as usize);
out.reserve_vertices(2 * n as usize);
let idx_inner = out.vertices.len() as u32;
let idx_outer = idx_inner + 1;
// The fill:
for i in 2..n {
out.add_triangle(idx_inner + 2 * (i - 1), idx_inner, idx_inner + 2 * i);
}
// The feathering:
let mut i0 = n - 1;
for i1 in 0..n {
let p1 = &path[i1 as usize];
let dm = 0.5 * feathering * p1.normal;
let pos_inner = p1.pos - dm;
let pos_outer = p1.pos + dm;
let color_outer = get_stroke_color(pos_outer);
out.colored_vertex(pos_inner, color);
out.colored_vertex(pos_outer, color_outer);
out.add_triangle(idx_inner + i1 * 2, idx_inner + i0 * 2, idx_outer + 2 * i0);
out.add_triangle(idx_outer + i0 * 2, idx_outer + i1 * 2, idx_inner + 2 * i1);
i0 = i1;
}
} else {
out.reserve_triangles(n as usize);
let idx = out.vertices.len() as u32;
out.vertices.extend(path.iter().map(|p| Vertex {
pos: p.pos,
uv: WHITE_UV,
color,
}));
for i in 2..n {
out.add_triangle(idx, idx + i - 1, idx + i);
}
}
}
/// Like [`fill_closed_path`] but with texturing.
///
/// The `uv_from_pos` is called for each vertex position.
fn fill_closed_path_with_uv(
feathering: f32,
path: &mut [PathPoint],
color: Color32,
texture_id: TextureId,
uv_from_pos: impl Fn(Pos2) -> Pos2,
out: &mut Mesh,
) {
if color == Color32::TRANSPARENT {
return;
}
if out.is_empty() {
out.texture_id = texture_id;
} else {
assert_eq!(
out.texture_id, texture_id,
"Mixing different `texture_id` in the same "
);
}
let n = path.len() as u32;
if feathering > 0.0 {
if cw_signed_area(path) < 0.0 {
// Wrong winding order - fix:
path.reverse();
for point in &mut *path {
point.normal = -point.normal;
}
}
out.reserve_triangles(3 * n as usize);
out.reserve_vertices(2 * n as usize);
let color_outer = Color32::TRANSPARENT;
let idx_inner = out.vertices.len() as u32;
let idx_outer = idx_inner + 1;
// The fill:
for i in 2..n {
out.add_triangle(idx_inner + 2 * (i - 1), idx_inner, idx_inner + 2 * i);
}
// The feathering:
let mut i0 = n - 1;
for i1 in 0..n {
let p1 = &path[i1 as usize];
let dm = 0.5 * feathering * p1.normal;
let pos = p1.pos - dm;
out.vertices.push(Vertex {
pos,
uv: uv_from_pos(pos),
color,
});
let pos = p1.pos + dm;
out.vertices.push(Vertex {
pos,
uv: uv_from_pos(pos),
color: color_outer,
});
out.add_triangle(idx_inner + i1 * 2, idx_inner + i0 * 2, idx_outer + 2 * i0);
out.add_triangle(idx_outer + i0 * 2, idx_outer + i1 * 2, idx_inner + 2 * i1);
i0 = i1;
}
} else {
out.reserve_triangles(n as usize);
let idx = out.vertices.len() as u32;
out.vertices.extend(path.iter().map(|p| Vertex {
pos: p.pos,
uv: uv_from_pos(p.pos),
color,
}));
for i in 2..n {
out.add_triangle(idx, idx + i - 1, idx + i);
}
}
}
/// Translate a point along their normals according to the stroke kind.
#[inline(always)]
fn translate_stroke_point(p: &mut PathPoint, stroke: &PathStroke) {
match stroke.kind {
stroke::StrokeKind::Middle => { /* Nothingn to do */ }
stroke::StrokeKind::Outside => {
p.pos += p.normal * stroke.width * 0.5;
}
stroke::StrokeKind::Inside => {
p.pos -= p.normal * stroke.width * 0.5;
}
}
}
/// Tessellate the given path as a stroke with thickness.
fn stroke_path(
feathering: f32,
path: &mut [PathPoint],
path_type: PathType,
stroke: &PathStroke,
out: &mut Mesh,
) {
let n = path.len() as u32;
if stroke.is_empty() || n < 2 {
return;
}
let idx = out.vertices.len() as u32;
// Translate the points along their normals if the stroke is outside or inside
if stroke.kind != stroke::StrokeKind::Middle {
path.iter_mut()
.for_each(|p| translate_stroke_point(p, stroke));
}
// expand the bounding box to include the thickness of the path
let bbox = Rect::from_points(&path.iter().map(|p| p.pos).collect::<Vec<Pos2>>())
.expand((stroke.width / 2.0) + feathering);
let get_color = |col: &ColorMode, pos: Pos2| match col {
ColorMode::Solid(col) => *col,
ColorMode::UV(fun) => fun(bbox, pos),
};
if feathering > 0.0 {
let color_inner = &stroke.color;
let color_outer = Color32::TRANSPARENT;
let thin_line = stroke.width <= feathering;
if thin_line {
/*
We paint the line using three edges: outer, inner, outer.
. o i o outer, inner, outer
. |---| feathering (pixel width)
*/
// Fade out as it gets thinner:
if let ColorMode::Solid(col) = color_inner {
let color_inner = mul_color(*col, stroke.width / feathering);
if color_inner == Color32::TRANSPARENT {
return;
}
}
out.reserve_triangles(4 * n as usize);
out.reserve_vertices(3 * n as usize);
let mut i0 = n - 1;
for i1 in 0..n {
let connect_with_previous = path_type == PathType::Closed || i1 > 0;
let p1 = path[i1 as usize];
let p = p1.pos;
let n = p1.normal;
out.colored_vertex(p + n * feathering, color_outer);
out.colored_vertex(
p,
mul_color(get_color(color_inner, p), stroke.width / feathering),
);
out.colored_vertex(p - n * feathering, color_outer);
if connect_with_previous {
out.add_triangle(idx + 3 * i0 + 0, idx + 3 * i0 + 1, idx + 3 * i1 + 0);
out.add_triangle(idx + 3 * i0 + 1, idx + 3 * i1 + 0, idx + 3 * i1 + 1);
out.add_triangle(idx + 3 * i0 + 1, idx + 3 * i0 + 2, idx + 3 * i1 + 1);
out.add_triangle(idx + 3 * i0 + 2, idx + 3 * i1 + 1, idx + 3 * i1 + 2);
}
i0 = i1;
}
} else {
// thick anti-aliased line
/*
We paint the line using four edges: outer, inner, inner, outer
. o i p i o outer, inner, point, inner, outer
. |---| feathering (pixel width)
. |--------------| width
. |---------| outer_rad
. |-----| inner_rad
*/
let inner_rad = 0.5 * (stroke.width - feathering);
let outer_rad = 0.5 * (stroke.width + feathering);
match path_type {
PathType::Closed => {
out.reserve_triangles(6 * n as usize);
out.reserve_vertices(4 * n as usize);
let mut i0 = n - 1;
for i1 in 0..n {
let p1 = path[i1 as usize];
let p = p1.pos;
let n = p1.normal;
out.colored_vertex(p + n * outer_rad, color_outer);
out.colored_vertex(
p + n * inner_rad,
get_color(color_inner, p + n * inner_rad),
);
out.colored_vertex(
p - n * inner_rad,
get_color(color_inner, p - n * inner_rad),
);
out.colored_vertex(p - n * outer_rad, color_outer);
out.add_triangle(idx + 4 * i0 + 0, idx + 4 * i0 + 1, idx + 4 * i1 + 0);
out.add_triangle(idx + 4 * i0 + 1, idx + 4 * i1 + 0, idx + 4 * i1 + 1);
out.add_triangle(idx + 4 * i0 + 1, idx + 4 * i0 + 2, idx + 4 * i1 + 1);
out.add_triangle(idx + 4 * i0 + 2, idx + 4 * i1 + 1, idx + 4 * i1 + 2);
out.add_triangle(idx + 4 * i0 + 2, idx + 4 * i0 + 3, idx + 4 * i1 + 2);
out.add_triangle(idx + 4 * i0 + 3, idx + 4 * i1 + 2, idx + 4 * i1 + 3);
i0 = i1;
}
}
PathType::Open => {
// Anti-alias the ends by extruding the outer edge and adding
// two more triangles to each end:
// | aa | | aa |
// _________________ ___
// | \ added / | feathering
// | \ ___p___ / | ___
// | | | |
// | | opa | |
// | | que | |
// | | | |
// (in the future it would be great with an option to add a circular end instead)
out.reserve_triangles(6 * n as usize + 4);
out.reserve_vertices(4 * n as usize);
{
let end = path[0];
let p = end.pos;
let n = end.normal;
let back_extrude = n.rot90() * feathering;
out.colored_vertex(p + n * outer_rad + back_extrude, color_outer);
out.colored_vertex(
p + n * inner_rad,
get_color(color_inner, p + n * inner_rad),
);
out.colored_vertex(
p - n * inner_rad,
get_color(color_inner, p - n * inner_rad),
);
out.colored_vertex(p - n * outer_rad + back_extrude, color_outer);
out.add_triangle(idx + 0, idx + 1, idx + 2);
out.add_triangle(idx + 0, idx + 2, idx + 3);
}
let mut i0 = 0;
for i1 in 1..n - 1 {
let point = path[i1 as usize];
let p = point.pos;
let n = point.normal;
out.colored_vertex(p + n * outer_rad, color_outer);
out.colored_vertex(
p + n * inner_rad,
get_color(color_inner, p + n * inner_rad),
);
out.colored_vertex(
p - n * inner_rad,
get_color(color_inner, p - n * inner_rad),
);
out.colored_vertex(p - n * outer_rad, color_outer);
out.add_triangle(idx + 4 * i0 + 0, idx + 4 * i0 + 1, idx + 4 * i1 + 0);
out.add_triangle(idx + 4 * i0 + 1, idx + 4 * i1 + 0, idx + 4 * i1 + 1);
out.add_triangle(idx + 4 * i0 + 1, idx + 4 * i0 + 2, idx + 4 * i1 + 1);
out.add_triangle(idx + 4 * i0 + 2, idx + 4 * i1 + 1, idx + 4 * i1 + 2);
out.add_triangle(idx + 4 * i0 + 2, idx + 4 * i0 + 3, idx + 4 * i1 + 2);
out.add_triangle(idx + 4 * i0 + 3, idx + 4 * i1 + 2, idx + 4 * i1 + 3);
i0 = i1;
}
{
let i1 = n - 1;
let end = path[i1 as usize];
let p = end.pos;
let n = end.normal;
let back_extrude = -n.rot90() * feathering;
out.colored_vertex(p + n * outer_rad + back_extrude, color_outer);
out.colored_vertex(
p + n * inner_rad,
get_color(color_inner, p + n * inner_rad),
);
out.colored_vertex(
p - n * inner_rad,
get_color(color_inner, p - n * inner_rad),
);
out.colored_vertex(p - n * outer_rad + back_extrude, color_outer);
out.add_triangle(idx + 4 * i0 + 0, idx + 4 * i0 + 1, idx + 4 * i1 + 0);
out.add_triangle(idx + 4 * i0 + 1, idx + 4 * i1 + 0, idx + 4 * i1 + 1);
out.add_triangle(idx + 4 * i0 + 1, idx + 4 * i0 + 2, idx + 4 * i1 + 1);
out.add_triangle(idx + 4 * i0 + 2, idx + 4 * i1 + 1, idx + 4 * i1 + 2);
out.add_triangle(idx + 4 * i0 + 2, idx + 4 * i0 + 3, idx + 4 * i1 + 2);
out.add_triangle(idx + 4 * i0 + 3, idx + 4 * i1 + 2, idx + 4 * i1 + 3);
// The extension:
out.add_triangle(idx + 4 * i1 + 0, idx + 4 * i1 + 1, idx + 4 * i1 + 2);
out.add_triangle(idx + 4 * i1 + 0, idx + 4 * i1 + 2, idx + 4 * i1 + 3);
}
}
}
}
} else {
// not anti-aliased:
out.reserve_triangles(2 * n as usize);
out.reserve_vertices(2 * n as usize);
let last_index = if path_type == PathType::Closed {
n
} else {
n - 1
};
for i in 0..last_index {
out.add_triangle(
idx + (2 * i + 0) % (2 * n),
idx + (2 * i + 1) % (2 * n),
idx + (2 * i + 2) % (2 * n),
);
out.add_triangle(
idx + (2 * i + 2) % (2 * n),
idx + (2 * i + 1) % (2 * n),
idx + (2 * i + 3) % (2 * n),
);
}
let thin_line = stroke.width <= feathering;
if thin_line {
// Fade out thin lines rather than making them thinner
let radius = feathering / 2.0;
if let ColorMode::Solid(color) = stroke.color {
let color = mul_color(color, stroke.width / feathering);
if color == Color32::TRANSPARENT {
return;
}
}
for p in path {
out.colored_vertex(
p.pos + radius * p.normal,
mul_color(
get_color(&stroke.color, p.pos + radius * p.normal),
stroke.width / feathering,
),
);
out.colored_vertex(
p.pos - radius * p.normal,
mul_color(
get_color(&stroke.color, p.pos - radius * p.normal),
stroke.width / feathering,
),
);
}
} else {
let radius = stroke.width / 2.0;
for p in path {
out.colored_vertex(
p.pos + radius * p.normal,
get_color(&stroke.color, p.pos + radius * p.normal),
);
out.colored_vertex(
p.pos - radius * p.normal,
get_color(&stroke.color, p.pos - radius * p.normal),
);
}
}
}
}
fn mul_color(color: Color32, factor: f32) -> Color32 {
// The fast gamma-space multiply also happens to be perceptually better.
// Win-win!
color.gamma_multiply(factor)
}
// ----------------------------------------------------------------------------
/// Converts [`Shape`]s into triangles ([`Mesh`]).
///
/// For performance reasons it is smart to reuse the same [`Tessellator`].
///
/// See also [`tessellate_shapes`], a convenient wrapper around [`Tessellator`].
#[derive(Clone)]
pub struct Tessellator {
pixels_per_point: f32,
options: TessellationOptions,
font_tex_size: [usize; 2],
/// See [`crate::TextureAtlas::prepared_discs`].
prepared_discs: Vec<PreparedDisc>,
/// size of feathering in points. normally the size of a physical pixel. 0.0 if disabled
feathering: f32,
/// Only used for culling
clip_rect: Rect,
scratchpad_points: Vec<Pos2>,
scratchpad_path: Path,
}
impl Tessellator {
/// Create a new [`Tessellator`].
///
/// * `pixels_per_point`: number of physical pixels to each logical point
/// * `options`: tessellation quality
/// * `shapes`: what to tessellate
/// * `font_tex_size`: size of the font texture. Required to normalize glyph uv rectangles when tessellating text.
/// * `prepared_discs`: What [`crate::TextureAtlas::prepared_discs`] returns. Can safely be set to an empty vec.
pub fn new(
pixels_per_point: f32,
options: TessellationOptions,
font_tex_size: [usize; 2],
prepared_discs: Vec<PreparedDisc>,
) -> Self {
let feathering = if options.feathering {
let pixel_size = 1.0 / pixels_per_point;
options.feathering_size_in_pixels * pixel_size
} else {
0.0
};
Self {
pixels_per_point,
options,
font_tex_size,
prepared_discs,
feathering,
clip_rect: Rect::EVERYTHING,
scratchpad_points: Default::default(),
scratchpad_path: Default::default(),
}
}
/// Set the [`Rect`] to use for culling.
pub fn set_clip_rect(&mut self, clip_rect: Rect) {
self.clip_rect = clip_rect;
}
#[inline(always)]
pub fn round_to_pixel(&self, point: f32) -> f32 {
(point * self.pixels_per_point).round() / self.pixels_per_point
}
#[inline(always)]
pub fn round_to_pixel_center(&self, point: f32) -> f32 {
((point * self.pixels_per_point - 0.5).round() + 0.5) / self.pixels_per_point
}
#[inline(always)]
pub fn round_pos_to_pixel(&self, pos: Pos2) -> Pos2 {
pos2(self.round_to_pixel(pos.x), self.round_to_pixel(pos.y))
}
#[inline(always)]
pub fn round_pos_to_pixel_center(&self, pos: Pos2) -> Pos2 {
pos2(
self.round_to_pixel_center(pos.x),
self.round_to_pixel_center(pos.y),
)
}
/// Tessellate a clipped shape into a list of primitives.
pub fn tessellate_clipped_shape(
&mut self,
clipped_shape: ClippedShape,
out_primitives: &mut Vec<ClippedPrimitive>,
) {
let ClippedShape { clip_rect, shape } = clipped_shape;
if !clip_rect.is_positive() {
return; // skip empty clip rectangles
}
if let Shape::Vec(shapes) = shape {
for shape in shapes {
self.tessellate_clipped_shape(ClippedShape { clip_rect, shape }, out_primitives);
}
return;
}
if let Shape::Callback(callback) = shape {
out_primitives.push(ClippedPrimitive {
clip_rect,
primitive: Primitive::Callback(callback),
});
return;
}
let start_new_mesh = match out_primitives.last() {
None => true,
Some(output_clipped_primitive) => {
output_clipped_primitive.clip_rect != clip_rect
|| match &output_clipped_primitive.primitive {
Primitive::Mesh(output_mesh) => {
output_mesh.texture_id != shape.texture_id()
}
Primitive::Callback(_) => true,
}
}
};
if start_new_mesh {
out_primitives.push(ClippedPrimitive {
clip_rect,
primitive: Primitive::Mesh(Mesh::default()),
});
}
let out = out_primitives.last_mut().unwrap();
if let Primitive::Mesh(out_mesh) = &mut out.primitive {
self.clip_rect = clip_rect;
self.tessellate_shape(shape, out_mesh);
} else {
unreachable!();
}
}
/// Tessellate a single [`Shape`] into a [`Mesh`].
///
/// This call can panic the given shape is of [`Shape::Vec`] or [`Shape::Callback`].
/// For that, use [`Self::tessellate_clipped_shape`] instead.
/// * `shape`: the shape to tessellate.
/// * `out`: triangles are appended to this.
pub fn tessellate_shape(&mut self, shape: Shape, out: &mut Mesh) {
match shape {
Shape::Noop => {}
Shape::Vec(vec) => {
for shape in vec {
self.tessellate_shape(shape, out);
}
}
Shape::Circle(circle) => {
self.tessellate_circle(circle, out);
}
Shape::Ellipse(ellipse) => {
self.tessellate_ellipse(ellipse, out);
}
Shape::Mesh(mesh) => {
profiling::scope!("mesh");
if self.options.validate_meshes && !mesh.is_valid() {
debug_assert!(false, "Invalid Mesh in Shape::Mesh");
return;
}
// note: `append` still checks if the mesh is valid if extra asserts are enabled.
if self.options.coarse_tessellation_culling
&& !self.clip_rect.intersects(mesh.calc_bounds())
{
return;
}
out.append(mesh);
}
Shape::LineSegment { points, stroke } => self.tessellate_line(points, stroke, out),
Shape::Path(path_shape) => {
self.tessellate_path(&path_shape, out);
}
Shape::Rect(rect_shape) => {
self.tessellate_rect(&rect_shape, out);
}
Shape::Text(text_shape) => {
if self.options.debug_paint_text_rects {
let rect = text_shape.galley.rect.translate(text_shape.pos.to_vec2());
self.tessellate_rect(
&RectShape::stroke(rect.expand(0.5), 2.0, (0.5, Color32::GREEN)),
out,
);
}
self.tessellate_text(&text_shape, out);
}
Shape::QuadraticBezier(quadratic_shape) => {
self.tessellate_quadratic_bezier(&quadratic_shape, out);
}
Shape::CubicBezier(cubic_shape) => self.tessellate_cubic_bezier(&cubic_shape, out),
Shape::Callback(_) => {
panic!("Shape::Callback passed to Tessellator");
}
}
}
/// Tessellate a single [`CircleShape`] into a [`Mesh`].
///
/// * `shape`: the circle to tessellate.
/// * `out`: triangles are appended to this.
pub fn tessellate_circle(&mut self, shape: CircleShape, out: &mut Mesh) {
let CircleShape {
center,
radius,
mut fill,
stroke,
} = shape;
if radius <= 0.0 {
return;
}
if self.options.coarse_tessellation_culling
&& !self
.clip_rect
.expand(radius + stroke.width)
.contains(center)
{
return;
}
if self.options.prerasterized_discs && fill != Color32::TRANSPARENT {
let radius_px = radius * self.pixels_per_point;
// strike the right balance between some circles becoming too blurry, and some too sharp.
let cutoff_radius = radius_px * 2.0_f32.powf(0.25);
// Find the right disc radius for a crisp edge:
// TODO(emilk): perhaps we can do something faster than this linear search.
for disc in &self.prepared_discs {
if cutoff_radius <= disc.r {
let side = radius_px * disc.w / (self.pixels_per_point * disc.r);
let rect = Rect::from_center_size(center, Vec2::splat(side));
out.add_rect_with_uv(rect, disc.uv, fill);
if stroke.is_empty() {
return; // we are done
} else {
// we still need to do the stroke
fill = Color32::TRANSPARENT; // don't fill again below
break;
}
}
}
}
let path_stroke = PathStroke::from(stroke).outside();
self.scratchpad_path.clear();
self.scratchpad_path.add_circle(center, radius);
self.scratchpad_path
.fill(self.feathering, fill, &path_stroke, out);
self.scratchpad_path
.stroke_closed(self.feathering, &path_stroke, out);
}
/// Tessellate a single [`EllipseShape`] into a [`Mesh`].
///
/// * `shape`: the ellipse to tessellate.
/// * `out`: triangles are appended to this.
pub fn tessellate_ellipse(&mut self, shape: EllipseShape, out: &mut Mesh) {
let EllipseShape {
center,
radius,
fill,
stroke,
} = shape;
if radius.x <= 0.0 || radius.y <= 0.0 {
return;
}
if self.options.coarse_tessellation_culling
&& !self
.clip_rect
.expand2(radius + Vec2::splat(stroke.width))
.contains(center)
{
return;
}
// Get the max pixel radius
let max_radius = (radius.max_elem() * self.pixels_per_point) as u32;
// Ensure there is at least 8 points in each quarter of the ellipse
let num_points = u32::max(8, max_radius / 16);
// Create an ease ratio based the ellipses a and b
let ratio = ((radius.y / radius.x) / 2.0).clamp(0.0, 1.0);
// Generate points between the 0 to pi/2
let quarter: Vec<Vec2> = (1..num_points)
.map(|i| {
let percent = i as f32 / num_points as f32;
// Ease the percent value, concentrating points around tight bends
let eased = 2.0 * (percent - percent.powf(2.0)) * ratio + percent.powf(2.0);
// Scale the ease to the quarter
let t = eased * std::f32::consts::FRAC_PI_2;
Vec2::new(radius.x * f32::cos(t), radius.y * f32::sin(t))
})
.collect();
// Build the ellipse from the 4 known vertices filling arcs between
// them by mirroring the points between 0 and pi/2
let mut points = Vec::new();
points.push(center + Vec2::new(radius.x, 0.0));
points.extend(quarter.iter().map(|p| center + *p));
points.push(center + Vec2::new(0.0, radius.y));
points.extend(quarter.iter().rev().map(|p| center + Vec2::new(-p.x, p.y)));
points.push(center + Vec2::new(-radius.x, 0.0));
points.extend(quarter.iter().map(|p| center - *p));
points.push(center + Vec2::new(0.0, -radius.y));
points.extend(quarter.iter().rev().map(|p| center + Vec2::new(p.x, -p.y)));
let path_stroke = PathStroke::from(stroke).outside();
self.scratchpad_path.clear();
self.scratchpad_path.add_line_loop(&points);
self.scratchpad_path
.fill(self.feathering, fill, &path_stroke, out);
self.scratchpad_path
.stroke_closed(self.feathering, &path_stroke, out);
}
/// Tessellate a single [`Mesh`] into a [`Mesh`].
///
/// * `mesh`: the mesh to tessellate.
/// * `out`: triangles are appended to this.
pub fn tessellate_mesh(&self, mesh: &Mesh, out: &mut Mesh) {
if !mesh.is_valid() {
debug_assert!(false, "Invalid Mesh in Shape::Mesh");
return;
}
if self.options.coarse_tessellation_culling
&& !self.clip_rect.intersects(mesh.calc_bounds())
{
return;
}
out.append_ref(mesh);
}
/// Tessellate a line segment between the two points with the given stroke into a [`Mesh`].
///
/// * `shape`: the mesh to tessellate.
/// * `out`: triangles are appended to this.
pub fn tessellate_line(
&mut self,
points: [Pos2; 2],
stroke: impl Into<PathStroke>,
out: &mut Mesh,
) {
let stroke = stroke.into();
if stroke.is_empty() {
return;
}
if self.options.coarse_tessellation_culling
&& !self
.clip_rect
.intersects(Rect::from_two_pos(points[0], points[1]).expand(stroke.width))
{
return;
}
self.scratchpad_path.clear();
self.scratchpad_path.add_line_segment(points);
self.scratchpad_path
.stroke_open(self.feathering, &stroke, out);
}
/// Tessellate a single [`PathShape`] into a [`Mesh`].
///
/// * `path_shape`: the path to tessellate.
/// * `out`: triangles are appended to this.
pub fn tessellate_path(&mut self, path_shape: &PathShape, out: &mut Mesh) {
if path_shape.points.len() < 2 {
return;
}
if self.options.coarse_tessellation_culling
&& !path_shape.visual_bounding_rect().intersects(self.clip_rect)
{
return;
}
profiling::function_scope!();
let PathShape {
points,
closed,
fill,
stroke,
} = path_shape;
self.scratchpad_path.clear();
if *closed {
self.scratchpad_path.add_line_loop(points);
} else {
self.scratchpad_path.add_open_points(points);
}
if *fill != Color32::TRANSPARENT {
debug_assert!(
closed,
"You asked to fill a path that is not closed. That makes no sense."
);
self.scratchpad_path
.fill(self.feathering, *fill, stroke, out);
}
let typ = if *closed {
PathType::Closed
} else {
PathType::Open
};
self.scratchpad_path
.stroke(self.feathering, typ, stroke, out);
}
/// Tessellate a single [`Rect`] into a [`Mesh`].
///
/// * `rect`: the rectangle to tessellate.
/// * `out`: triangles are appended to this.
pub fn tessellate_rect(&mut self, rect: &RectShape, out: &mut Mesh) {
let RectShape {
mut rect,
mut rounding,
fill,
stroke,
mut blur_width,
fill_texture_id,
uv,
} = *rect;
if self.options.coarse_tessellation_culling
&& !rect.expand(stroke.width).intersects(self.clip_rect)
{
return;
}
if rect.is_negative() {
return;
}
// It is common to (sometimes accidentally) create an infinitely sized rectangle.
// Make sure we can handle that:
rect.min = rect.min.at_least(pos2(-1e7, -1e7));
rect.max = rect.max.at_most(pos2(1e7, 1e7));
let old_feathering = self.feathering;
if old_feathering < blur_width {
// We accomplish the blur by using a larger-than-normal feathering.
// Feathering is usually used to make the edges of a shape softer for anti-aliasing.
// The tessellator can't handle blurring/feathering larger than the smallest side of the rect.
// Thats because the tessellator approximate very thin rectangles as line segments,
// and these line segments don't have rounded corners.
// When the feathering is small (the size of a pixel), this is usually fine,
// but here we have a huge feathering to simulate blur,
// so we need to avoid this optimization in the tessellator,
// which is also why we add this rather big epsilon:
let eps = 0.1;
blur_width = blur_width
.at_most(rect.size().min_elem() - eps)
.at_least(0.0);
rounding += Rounding::same(0.5 * blur_width);
self.feathering = self.feathering.max(blur_width);
}
if rect.width() < self.feathering {
// Very thin - approximate by a vertical line-segment:
let line = [rect.center_top(), rect.center_bottom()];
if fill != Color32::TRANSPARENT {
self.tessellate_line(line, Stroke::new(rect.width(), fill), out);
}
if !stroke.is_empty() {
self.tessellate_line(line, stroke, out); // back…
self.tessellate_line(line, stroke, out); // …and forth
}
} else if rect.height() < self.feathering {
// Very thin - approximate by a horizontal line-segment:
let line = [rect.left_center(), rect.right_center()];
if fill != Color32::TRANSPARENT {
self.tessellate_line(line, Stroke::new(rect.height(), fill), out);
}
if !stroke.is_empty() {
self.tessellate_line(line, stroke, out); // back…
self.tessellate_line(line, stroke, out); // …and forth
}
} else {
let rect = if !stroke.is_empty() && stroke.width < self.feathering {
// Very thin rectangle strokes create extreme aliasing when they move around.
// We can fix that by rounding the rectangle corners to pixel centers.
// TODO(#5164): maybe do this for all shapes and stroke sizes
// TODO(emilk): since we use StrokeKind::Outside, we should probably round the
// corners after offsetting them with half the stroke width (see `translate_stroke_point`).
Rect {
min: self.round_pos_to_pixel_center(rect.min),
max: self.round_pos_to_pixel_center(rect.max),
}
} else {
rect
};
let path = &mut self.scratchpad_path;
path.clear();
path::rounded_rectangle(&mut self.scratchpad_points, rect, rounding);
path.add_line_loop(&self.scratchpad_points);
let path_stroke = PathStroke::from(stroke).outside();
if uv.is_positive() {
// Textured
let uv_from_pos = |p: Pos2| {
pos2(
remap(p.x, rect.x_range(), uv.x_range()),
remap(p.y, rect.y_range(), uv.y_range()),
)
};
path.fill_with_uv(self.feathering, fill, fill_texture_id, uv_from_pos, out);
} else {
// Untextured
path.fill(self.feathering, fill, &path_stroke, out);
}
path.stroke_closed(self.feathering, &path_stroke, out);
}
self.feathering = old_feathering; // restore
}
/// Tessellate a single [`TextShape`] into a [`Mesh`].
/// * `text_shape`: the text to tessellate.
/// * `out`: triangles are appended to this.
pub fn tessellate_text(&mut self, text_shape: &TextShape, out: &mut Mesh) {
let TextShape {
pos: galley_pos,
galley,
underline,
override_text_color,
fallback_color,
opacity_factor,
angle,
} = text_shape;
if galley.is_empty() {
return;
}
if *opacity_factor <= 0.0 {
return;
}
if galley.pixels_per_point != self.pixels_per_point {
let warn = "epaint: WARNING: pixels_per_point (dpi scale) have changed between text layout and tessellation. \
You must recreate your text shapes if pixels_per_point changes.";
#[cfg(feature = "log")]
log::warn!("{warn}");
#[cfg(not(feature = "log"))]
println!("{warn}");
}
out.vertices.reserve(galley.num_vertices);
out.indices.reserve(galley.num_indices);
// The contents of the galley are already snapped to pixel coordinates,
// but we need to make sure the galley ends up on the start of a physical pixel:
let galley_pos = if self.options.round_text_to_pixels {
pos2(
self.round_to_pixel(galley_pos.x),
self.round_to_pixel(galley_pos.y),
)
} else {
*galley_pos
};
let uv_normalizer = vec2(
1.0 / self.font_tex_size[0] as f32,
1.0 / self.font_tex_size[1] as f32,
);
let rotator = Rot2::from_angle(*angle);
for row in &galley.rows {
if row.visuals.mesh.is_empty() {
continue;
}
let mut row_rect = row.visuals.mesh_bounds;
if *angle != 0.0 {
row_rect = row_rect.rotate_bb(rotator);
}
row_rect = row_rect.translate(galley_pos.to_vec2());
if self.options.coarse_tessellation_culling && !self.clip_rect.intersects(row_rect) {
// culling individual lines of text is important, since a single `Shape::Text`
// can span hundreds of lines.
continue;
}
let index_offset = out.vertices.len() as u32;
out.indices.extend(
row.visuals
.mesh
.indices
.iter()
.map(|index| index + index_offset),
);
out.vertices.extend(
row.visuals
.mesh
.vertices
.iter()
.enumerate()
.map(|(i, vertex)| {
let Vertex { pos, uv, mut color } = *vertex;
if let Some(override_text_color) = override_text_color {
// Only override the glyph color (not background color, strike-through color, etc)
if row.visuals.glyph_vertex_range.contains(&i) {
color = *override_text_color;
}
} else if color == Color32::PLACEHOLDER {
color = *fallback_color;
}
if *opacity_factor < 1.0 {
color = color.gamma_multiply(*opacity_factor);
}
debug_assert!(color != Color32::PLACEHOLDER, "A placeholder color made it to the tessellator. You forgot to set a fallback color.");
let offset = if *angle == 0.0 {
pos.to_vec2()
} else {
rotator * pos.to_vec2()
};
Vertex {
pos: galley_pos + offset,
uv: (uv.to_vec2() * uv_normalizer).to_pos2(),
color,
}
}),
);
if *underline != Stroke::NONE {
self.scratchpad_path.clear();
self.scratchpad_path.add_line_segment([
self.round_pos_to_pixel_center(row_rect.left_bottom()),
self.round_pos_to_pixel_center(row_rect.right_bottom()),
]);
self.scratchpad_path
.stroke_open(0.0, &PathStroke::from(*underline), out);
}
}
}
/// Tessellate a single [`QuadraticBezierShape`] into a [`Mesh`].
///
/// * `quadratic_shape`: the shape to tessellate.
/// * `out`: triangles are appended to this.
pub fn tessellate_quadratic_bezier(
&mut self,
quadratic_shape: &QuadraticBezierShape,
out: &mut Mesh,
) {
let options = &self.options;
let clip_rect = self.clip_rect;
if options.coarse_tessellation_culling
&& !quadratic_shape.visual_bounding_rect().intersects(clip_rect)
{
return;
}
let points = quadratic_shape.flatten(Some(options.bezier_tolerance));
self.tessellate_bezier_complete(
&points,
quadratic_shape.fill,
quadratic_shape.closed,
&quadratic_shape.stroke,
out,
);
}
/// Tessellate a single [`CubicBezierShape`] into a [`Mesh`].
///
/// * `cubic_shape`: the shape to tessellate.
/// * `out`: triangles are appended to this.
pub fn tessellate_cubic_bezier(&mut self, cubic_shape: &CubicBezierShape, out: &mut Mesh) {
let options = &self.options;
let clip_rect = self.clip_rect;
if options.coarse_tessellation_culling
&& !cubic_shape.visual_bounding_rect().intersects(clip_rect)
{
return;
}
let points_vec =
cubic_shape.flatten_closed(Some(options.bezier_tolerance), Some(options.epsilon));
for points in points_vec {
self.tessellate_bezier_complete(
&points,
cubic_shape.fill,
cubic_shape.closed,
&cubic_shape.stroke,
out,
);
}
}
fn tessellate_bezier_complete(
&mut self,
points: &[Pos2],
fill: Color32,
closed: bool,
stroke: &PathStroke,
out: &mut Mesh,
) {
if points.len() < 2 {
return;
}
self.scratchpad_path.clear();
if closed {
self.scratchpad_path.add_line_loop(points);
} else {
self.scratchpad_path.add_open_points(points);
}
if fill != Color32::TRANSPARENT {
debug_assert!(
closed,
"You asked to fill a path that is not closed. That makes no sense."
);
self.scratchpad_path
.fill(self.feathering, fill, stroke, out);
}
let typ = if closed {
PathType::Closed
} else {
PathType::Open
};
self.scratchpad_path
.stroke(self.feathering, typ, stroke, out);
}
}
#[deprecated = "Use `Tessellator::new(…).tessellate_shapes(…)` instead"]
pub fn tessellate_shapes(
pixels_per_point: f32,
options: TessellationOptions,
font_tex_size: [usize; 2],
prepared_discs: Vec<PreparedDisc>,
shapes: Vec<ClippedShape>,
) -> Vec<ClippedPrimitive> {
Tessellator::new(pixels_per_point, options, font_tex_size, prepared_discs)
.tessellate_shapes(shapes)
}
impl Tessellator {
/// Turns [`Shape`]:s into sets of triangles.
///
/// The given shapes will tessellated in the same order as they are given.
/// They will be batched together by clip rectangle.
///
/// * `pixels_per_point`: number of physical pixels to each logical point
/// * `options`: tessellation quality
/// * `shapes`: what to tessellate
/// * `font_tex_size`: size of the font texture. Required to normalize glyph uv rectangles when tessellating text.
/// * `prepared_discs`: What [`crate::TextureAtlas::prepared_discs`] returns. Can safely be set to an empty vec.
///
/// The implementation uses a [`Tessellator`].
///
/// ## Returns
/// A list of clip rectangles with matching [`Mesh`].
#[allow(unused_mut)]
pub fn tessellate_shapes(&mut self, mut shapes: Vec<ClippedShape>) -> Vec<ClippedPrimitive> {
profiling::function_scope!();
#[cfg(feature = "rayon")]
if self.options.parallel_tessellation {
self.parallel_tessellation_of_large_shapes(&mut shapes);
}
let mut clipped_primitives: Vec<ClippedPrimitive> = Vec::default();
{
profiling::scope!("tessellate");
for clipped_shape in shapes {
self.tessellate_clipped_shape(clipped_shape, &mut clipped_primitives);
}
}
if self.options.debug_paint_clip_rects {
clipped_primitives = self.add_clip_rects(clipped_primitives);
}
if self.options.debug_ignore_clip_rects {
for clipped_primitive in &mut clipped_primitives {
clipped_primitive.clip_rect = Rect::EVERYTHING;
}
}
clipped_primitives.retain(|p| {
p.clip_rect.is_positive()
&& match &p.primitive {
Primitive::Mesh(mesh) => !mesh.is_empty(),
Primitive::Callback(_) => true,
}
});
for clipped_primitive in &clipped_primitives {
if let Primitive::Mesh(mesh) = &clipped_primitive.primitive {
debug_assert!(mesh.is_valid(), "Tessellator generated invalid Mesh");
}
}
clipped_primitives
}
/// Find large shapes and throw them on the rayon thread pool,
/// then replace the original shape with their tessellated meshes.
#[cfg(feature = "rayon")]
fn parallel_tessellation_of_large_shapes(&self, shapes: &mut [ClippedShape]) {
profiling::function_scope!();
use rayon::prelude::*;
// We only parallelize large/slow stuff, because each tessellation job
// will allocate a new Mesh, and so it creates a lot of extra memory fragmentation
// and allocations that is only worth it for large shapes.
fn should_parallelize(shape: &Shape) -> bool {
match shape {
Shape::Vec(shapes) => 4 < shapes.len() || shapes.iter().any(should_parallelize),
Shape::Path(path_shape) => 32 < path_shape.points.len(),
Shape::QuadraticBezier(_) | Shape::CubicBezier(_) | Shape::Ellipse(_) => true,
Shape::Noop
| Shape::Text(_)
| Shape::Circle(_)
| Shape::Mesh(_)
| Shape::LineSegment { .. }
| Shape::Rect(_)
| Shape::Callback(_) => false,
}
}
let tessellated: Vec<(usize, Mesh)> = shapes
.par_iter()
.enumerate()
.filter(|(_, clipped_shape)| should_parallelize(&clipped_shape.shape))
.map(|(index, clipped_shape)| {
profiling::scope!("tessellate_big_shape");
// TODO(emilk): reuse tessellator in a thread local
let mut tessellator = (*self).clone();
let mut mesh = Mesh::default();
tessellator.tessellate_shape(clipped_shape.shape.clone(), &mut mesh);
(index, mesh)
})
.collect();
profiling::scope!("distribute results", tessellated.len().to_string());
for (index, mesh) in tessellated {
shapes[index].shape = Shape::Mesh(mesh);
}
}
fn add_clip_rects(
&mut self,
clipped_primitives: Vec<ClippedPrimitive>,
) -> Vec<ClippedPrimitive> {
self.clip_rect = Rect::EVERYTHING;
let stroke = Stroke::new(2.0, Color32::from_rgb(150, 255, 150));
clipped_primitives
.into_iter()
.flat_map(|clipped_primitive| {
let mut clip_rect_mesh = Mesh::default();
self.tessellate_shape(
Shape::rect_stroke(clipped_primitive.clip_rect, 0.0, stroke),
&mut clip_rect_mesh,
);
[
clipped_primitive,
ClippedPrimitive {
clip_rect: Rect::EVERYTHING, // whatever
primitive: Primitive::Mesh(clip_rect_mesh),
},
]
})
.collect()
}
}
#[test]
fn test_tessellator() {
use crate::*;
let mut shapes = Vec::with_capacity(2);
let rect = Rect::from_min_max(pos2(0.0, 0.0), pos2(1.0, 1.0));
let uv = Rect::from_min_max(pos2(0.0, 0.0), pos2(1.0, 1.0));
let mut mesh = Mesh::with_texture(TextureId::Managed(1));
mesh.add_rect_with_uv(rect, uv, Color32::WHITE);
shapes.push(Shape::mesh(mesh));
let mut mesh = Mesh::with_texture(TextureId::Managed(2));
mesh.add_rect_with_uv(rect, uv, Color32::WHITE);
shapes.push(Shape::mesh(mesh));
let shape = Shape::Vec(shapes);
let clipped_shapes = vec![ClippedShape {
clip_rect: rect,
shape,
}];
let font_tex_size = [1024, 1024]; // unused
let prepared_discs = vec![]; // unused
let primitives = Tessellator::new(1.0, Default::default(), font_tex_size, prepared_discs)
.tessellate_shapes(clipped_shapes);
assert_eq!(primitives.len(), 2);
}
#[test]
fn path_bounding_box() {
use crate::*;
for i in 1..=100 {
let width = i as f32;
let rect = Rect::from_min_max(pos2(0.0, 0.0), pos2(10.0, 10.0));
let expected_rect = rect.expand((width / 2.0) + 1.5);
let mut mesh = Mesh::default();
let mut path = Path::default();
path.add_open_points(&[
pos2(0.0, 0.0),
pos2(2.0, 0.0),
pos2(5.0, 5.0),
pos2(0.0, 5.0),
pos2(0.0, 7.0),
pos2(10.0, 10.0),
]);
path.stroke(
1.5,
PathType::Closed,
&PathStroke::new_uv(width, move |r, p| {
assert_eq!(r, expected_rect);
// see https://github.com/emilk/egui/pull/4353#discussion_r1573879940 for why .contains() isn't used here.
// TL;DR rounding errors.
assert!(
r.distance_to_pos(p) <= 0.55,
"passed rect {r:?} didn't contain point {p:?} (distance: {})",
r.distance_to_pos(p)
);
assert!(
expected_rect.distance_to_pos(p) <= 0.55,
"expected rect {expected_rect:?} didn't contain point {p:?}"
);
Color32::WHITE
}),
&mut mesh,
);
}
}