Disable custom 3D painting example in the egui demo app for Es100 (#1945)

Closes https://github.com/emilk/egui/issues/1944

Cargo.lock

@@ -1259,6 +1259,7 @@ dependencies = [
  "poll-promise",
  "pollster",
  "serde",
+ "tracing",
  "tracing-subscriber",
  "tracing-wasm",
  "wgpu",

crates/eframe/Cargo.toml

@@ -55,7 +55,7 @@ screen_reader = [
   "tts",
 ]
 
-## Use [`wgpu`](https://docs.rs/wgpu) for painting (via [`egui_wgpu`](https://github.com/emilk/egui/tree/master/crates/egui_wgpu)).
+## Use [`wgpu`](https://docs.rs/wgpu) for painting (via [`egui-wgpu`](https://github.com/emilk/egui/tree/master/crates/egui-wgpu)).
 ## This overrides the `glow` feature.
 wgpu = ["dep:wgpu", "egui-wgpu"]
 

crates/egui_demo_app/Cargo.toml

@@ -42,6 +42,7 @@ chrono = { version = "0.4", features = ["js-sys", "wasmbind"] }
 eframe = { version = "0.19.0", path = "../eframe", default-features = false }
 egui = { version = "0.19.0", path = "../egui", features = ["extra_debug_asserts"] }
 egui_demo_lib = { version = "0.19.0", path = "../egui_demo_lib", features = ["chrono"] }
+tracing = "0.1"
 
 # Optional dependencies:
 

crates/egui_demo_app/src/apps/custom3d_glow.rs

@@ -11,13 +11,12 @@ pub struct Custom3d {
 }
 
 impl Custom3d {
-    pub fn new<'a>(cc: &'a eframe::CreationContext<'a>) -> Self {
-        Self {
-            rotating_triangle: Arc::new(Mutex::new(RotatingTriangle::new(
-                cc.gl.as_ref().expect("GL Enabled"),
-            ))),
+    pub fn new<'a>(cc: &'a eframe::CreationContext<'a>) -> Option<Self> {
+        let gl = cc.gl.as_ref()?;
+        Some(Self {
+            rotating_triangle: Arc::new(Mutex::new(RotatingTriangle::new(gl)?)),
             angle: 0.0,
-        }
+        })
     }
 }
 
@@ -81,18 +80,22 @@ struct RotatingTriangle {
 
 #[allow(unsafe_code)] // we need unsafe code to use glow
 impl RotatingTriangle {
-    fn new(gl: &glow::Context) -> Self {
+    fn new(gl: &glow::Context) -> Option<Self> {
         use glow::HasContext as _;
 
-        let shader_version = if cfg!(target_arch = "wasm32") {
-            "#version 300 es"
-        } else {
-            "#version 330"
-        };
+        let shader_version = egui_glow::ShaderVersion::get(gl);
 
         unsafe {
             let program = gl.create_program().expect("Cannot create program");
 
+            if !shader_version.is_new_shader_interface() {
+                tracing::warn!(
+                    "Custom 3D painting hasn't been ported to {:?}",
+                    shader_version
+                );
+                return None;
+            }
+
             let (vertex_shader_source, fragment_shader_source) = (
                 r#"
                     const vec2 verts[3] = vec2[3](
@@ -134,10 +137,20 @@ impl RotatingTriangle {
                     let shader = gl
                         .create_shader(*shader_type)
                         .expect("Cannot create shader");
-                    gl.shader_source(shader, &format!("{}\n{}", shader_version, shader_source));
+                    gl.shader_source(
+                        shader,
+                        &format!(
+                            "{}\n{}",
+                            shader_version.version_declaration(),
+                            shader_source
+                        ),
+                    );
                     gl.compile_shader(shader);
                     if !gl.get_shader_compile_status(shader) {
-                        panic!("{}", gl.get_shader_info_log(shader));
+                        panic!(
+                            "Failed to compile custom_3d_glow: {}",
+                            gl.get_shader_info_log(shader)
+                        );
                     }
                     gl.attach_shader(program, shader);
                     shader
@@ -158,10 +171,10 @@ impl RotatingTriangle {
                 .create_vertex_array()
                 .expect("Cannot create vertex array");
 
-            Self {
+            Some(Self {
                 program,
                 vertex_array,
-            }
+            })
         }
     }
 

crates/egui_demo_app/src/apps/custom3d_wgpu.rs

@@ -10,10 +10,10 @@ pub struct Custom3d {
 }
 
 impl Custom3d {
-    pub fn new<'a>(cc: &'a eframe::CreationContext<'a>) -> Self {
+    pub fn new<'a>(cc: &'a eframe::CreationContext<'a>) -> Option<Self> {
         // Get the WGPU render state from the eframe creation context. This can also be retrieved
         // from `eframe::Frame` when you don't have a `CreationContext` available.
-        let wgpu_render_state = cc.wgpu_render_state.as_ref().expect("WGPU enabled");
+        let wgpu_render_state = cc.wgpu_render_state.as_ref()?;
 
         let device = &wgpu_render_state.device;
 
@@ -91,7 +91,7 @@ impl Custom3d {
                 uniform_buffer,
             });
 
-        Self { angle: 0.0 }
+        Some(Self { angle: 0.0 })
     }
 }
 

crates/egui_demo_app/src/wrap_app.rs

@@ -95,7 +95,7 @@ pub struct WrapApp {
     state: State,
 
     #[cfg(any(feature = "glow", feature = "wgpu"))]
-    custom3d: crate::apps::Custom3d,
+    custom3d: Option<crate::apps::Custom3d>,
 
     dropped_files: Vec<egui::DroppedFile>,
 }
@@ -148,11 +148,13 @@ impl WrapApp {
         ];
 
         #[cfg(any(feature = "glow", feature = "wgpu"))]
-        vec.push((
-            "🔺 3D painting",
-            "custom3d",
-            &mut self.custom3d as &mut dyn eframe::App,
-        ));
+        if let Some(custom3d) = &mut self.custom3d {
+            vec.push((
+                "🔺 3D painting",
+                "custom3d",
+                custom3d as &mut dyn eframe::App,
+            ));
+        }
 
         vec.push((
             "🎨 Color test",
@@ -219,7 +221,9 @@ impl eframe::App for WrapApp {
 
     #[cfg(feature = "glow")]
     fn on_exit(&mut self, gl: Option<&glow::Context>) {
-        self.custom3d.on_exit(gl);
+        if let Some(custom3d) = &mut self.custom3d {
+            custom3d.on_exit(gl);
+        }
     }
 }
 

crates/egui_glow/src/lib.rs

@@ -19,6 +19,8 @@ mod post_process;
 mod shader_version;
 mod vao;
 
+pub use shader_version::ShaderVersion;
+
 #[cfg(all(not(target_arch = "wasm32"), feature = "winit"))]
 pub mod winit;
 #[cfg(all(not(target_arch = "wasm32"), feature = "winit"))]

crates/egui_glow/src/painter.rs

@@ -114,7 +114,7 @@ impl Painter {
 
         let shader_version = ShaderVersion::get(&gl);
         let is_webgl_1 = shader_version == ShaderVersion::Es100;
-        let header = shader_version.version();
+        let header = shader_version.version_declaration();
         tracing::debug!("Shader header: {:?}.", header);
         let srgb_support = gl.supported_extensions().contains("EXT_sRGB");
 
@@ -155,7 +155,11 @@ impl Painter {
                     "{}\n{}\n{}\n{}",
                     header,
                     shader_prefix,
-                    shader_version.is_new_shader_interface(),
+                    if shader_version.is_new_shader_interface() {
+                        "#define NEW_SHADER_INTERFACE\n"
+                    } else {
+                        ""
+                    },
                     VERT_SRC
                 ),
             )?;
@@ -167,7 +171,11 @@ impl Painter {
                     header,
                     shader_prefix,
                     srgb_support_define,
-                    shader_version.is_new_shader_interface(),
+                    if shader_version.is_new_shader_interface() {
+                        "#define NEW_SHADER_INTERFACE\n"
+                    } else {
+                        ""
+                    },
                     FRAG_SRC
                 ),
             )?;

crates/egui_glow/src/shader_version.rs

@@ -2,9 +2,10 @@
 
 use std::convert::TryInto;
 
+/// Helper for parsing and interpreting the OpenGL shader version.
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 #[allow(dead_code)]
-pub(crate) enum ShaderVersion {
+pub enum ShaderVersion {
     Gl120,
     Gl140,
     Es100,
@@ -12,7 +13,7 @@ pub(crate) enum ShaderVersion {
 }
 
 impl ShaderVersion {
-    pub(crate) fn get(gl: &glow::Context) -> Self {
+    pub fn get(gl: &glow::Context) -> Self {
         use glow::HasContext as _;
         let shading_lang_string =
             unsafe { gl.get_parameter_string(glow::SHADING_LANGUAGE_VERSION) };
@@ -52,7 +53,8 @@ impl ShaderVersion {
         }
     }
 
-    pub(crate) fn version(&self) -> &'static str {
+    /// Goes on top of the shader.
+    pub fn version_declaration(&self) -> &'static str {
         match self {
             Self::Gl120 => "#version 120\n",
             Self::Gl140 => "#version 140\n",
@@ -61,10 +63,11 @@ impl ShaderVersion {
         }
     }
 
-    pub(crate) fn is_new_shader_interface(&self) -> &'static str {
+    /// If true, use `in/out`. If `false`, use `varying` and `gl_FragColor`.
+    pub fn is_new_shader_interface(&self) -> bool {
         match self {
-            ShaderVersion::Es300 | ShaderVersion::Gl140 => "#define NEW_SHADER_INTERFACE\n",
-            _ => "",
+            Self::Gl120 | Self::Es100 => false,
+            Self::Es300 | Self::Gl140 => true,
         }
     }
 }