Add custom shader_version on glow renderer (#1993)

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

crates/eframe/CHANGELOG.md

@@ -8,7 +8,7 @@ NOTE: [`egui-winit`](../egui-winit/CHANGELOG.md), [`egui_glium`](../egui_glium/C
 * Added `NativeOptions::event_loop_builder` hook for apps to change platform specific event loop options ([#1952](https://github.com/emilk/egui/pull/1952)).
 * Enabled deferred render state initialization to support Android ([#1952](https://github.com/emilk/egui/pull/1952)).
 * Allow empty textures with the glow renderer.
-
+* Added `shader_version` to `NativeOptions` for cross compilling support on different target OpenGL | ES versions (on native `glow` renderer only) ([#1993](https://github.com/emilk/egui/pull/1993))..
 
 ## 0.19.0 - 2022-08-20
 * MSRV (Minimum Supported Rust Version) is now `1.61.0` ([#1846](https://github.com/emilk/egui/pull/1846)).

crates/eframe/src/epi.rs

@@ -311,6 +311,13 @@ pub struct NativeOptions {
     ///
     /// Note: A [`NativeOptions`] clone will not include any `event_loop_builder` hook.
     pub event_loop_builder: Option<EventLoopBuilderHook>,
+
+    #[cfg(feature = "glow")]
+    /// Needed for cross compiling for VirtualBox VMSVGA driver with OpenGL ES 2.0 and OpenGL 2.1 which doesn't support SRGB texture.
+    /// See <https://github.com/emilk/egui/pull/1993>.
+    ///
+    /// For OpenGL ES 2.0: set this to [`egui_glow::ShaderVersion::Es100`] to solve blank texture problem (by using the "fallback shader").
+    pub shader_version: Option<egui_glow::ShaderVersion>,
 }
 
 #[cfg(not(target_arch = "wasm32"))]
@@ -350,6 +357,8 @@ impl Default for NativeOptions {
             default_theme: Theme::Dark,
             run_and_return: true,
             event_loop_builder: None,
+            #[cfg(feature = "glow")]
+            shader_version: None,
         }
     }
 }

crates/eframe/src/native/run.rs

@@ -337,7 +337,8 @@ mod glow_integration {
             );
             let gl = Arc::new(gl);
 
-            let painter = egui_glow::Painter::new(gl.clone(), None, "")
+            let painter =
+                egui_glow::Painter::new(gl.clone(), None, "", self.native_options.shader_version)
                     .unwrap_or_else(|error| panic!("some OpenGL error occurred {}\n", error));
 
             let system_theme = self.native_options.system_theme();

crates/eframe/src/web/web_glow_painter.rs

@@ -23,7 +23,7 @@ impl WebPainter {
         let gl = std::sync::Arc::new(gl);
 
         let dimension = [canvas.width() as i32, canvas.height() as i32];
-        let painter = egui_glow::Painter::new(gl, Some(dimension), shader_prefix)
+        let painter = egui_glow::Painter::new(gl, Some(dimension), shader_prefix, None)
             .map_err(|error| format!("Error starting glow painter: {}", error))?;
 
         Ok(Self {

crates/egui_glow/CHANGELOG.md

@@ -4,7 +4,7 @@ All notable changes to the `egui_glow` integration will be noted in this file.
 
 ## Unreleased
 * Allow empty textures.
-
+* Added `shader_version` variable on `EguiGlow::new` for easier cross compilling on different OpenGL | ES targets ([#1993](https://github.com/emilk/egui/pull/1993)).
 
 ## 0.19.0 - 2022-08-20
 * MSRV (Minimum Supported Rust Version) is now `1.61.0` ([#1846](https://github.com/emilk/egui/pull/1846)).

crates/egui_glow/examples/pure_glow.rs

@@ -10,7 +10,7 @@ fn main() {
     let (gl_window, gl) = create_display(&event_loop);
     let gl = std::sync::Arc::new(gl);
 
-    let mut egui_glow = egui_glow::EguiGlow::new(&event_loop, gl.clone());
+    let mut egui_glow = egui_glow::EguiGlow::new(&event_loop, gl.clone(), None);
 
     event_loop.run(move |event, _, control_flow| {
         let mut redraw = || {

crates/egui_glow/src/painter.rs

@@ -106,20 +106,20 @@ impl Painter {
         gl: Arc<glow::Context>,
         pp_fb_extent: Option<[i32; 2]>,
         shader_prefix: &str,
+        shader_version: Option<ShaderVersion>,
     ) -> Result<Painter, String> {
         crate::profile_function!();
         crate::check_for_gl_error_even_in_release!(&gl, "before Painter::new");
 
         let max_texture_side = unsafe { gl.get_parameter_i32(glow::MAX_TEXTURE_SIZE) } as usize;
-
-        let shader_version = ShaderVersion::get(&gl);
-        let is_webgl_1 = shader_version == ShaderVersion::Es100;
-        let header = shader_version.version_declaration();
+        let shader = shader_version.unwrap_or_else(|| ShaderVersion::get(&gl));
+        let is_webgl_1 = shader == ShaderVersion::Es100;
+        let header = shader.version_declaration();
         tracing::debug!("Shader header: {:?}.", header);
         let srgb_support = gl.supported_extensions().contains("EXT_sRGB");
         tracing::debug!("SRGB Support: {:?}.", srgb_support);
 
-        let (post_process, srgb_support_define) = match (shader_version, srgb_support) {
+        let (post_process, srgb_support_define) = match (shader, srgb_support) {
             // WebGL2 support sRGB default
             (ShaderVersion::Es300, _) | (ShaderVersion::Es100, true) => unsafe {
                 // Add sRGB support marker for fragment shader
@@ -156,7 +156,7 @@ impl Painter {
                     "{}\n{}\n{}\n{}",
                     header,
                     shader_prefix,
-                    if shader_version.is_new_shader_interface() {
+                    if shader.is_new_shader_interface() {
                         "#define NEW_SHADER_INTERFACE\n"
                     } else {
                         ""
@@ -172,7 +172,7 @@ impl Painter {
                     header,
                     shader_prefix,
                     srgb_support_define,
-                    if shader_version.is_new_shader_interface() {
+                    if shader.is_new_shader_interface() {
                         "#define NEW_SHADER_INTERFACE\n"
                     } else {
                         ""
@@ -234,7 +234,7 @@ impl Painter {
                 u_screen_size,
                 u_sampler,
                 is_webgl_1,
-                is_embedded: matches!(shader_version, ShaderVersion::Es100 | ShaderVersion::Es300),
+                is_embedded: matches!(shader, ShaderVersion::Es100 | ShaderVersion::Es300),
                 vao,
                 srgb_support,
                 post_process,

crates/egui_glow/src/winit.rs

@@ -1,7 +1,7 @@
+use crate::shader_version::ShaderVersion;
 pub use egui_winit;
-pub use egui_winit::EventResponse;
-
 use egui_winit::winit;
+pub use egui_winit::EventResponse;
 
 /// Use [`egui`] from a [`glow`] app based on [`winit`].
 pub struct EguiGlow {
@@ -14,11 +14,13 @@ pub struct EguiGlow {
 }
 
 impl EguiGlow {
+    /// For automatic shader version detection set `shader_version` to `None`.
     pub fn new<E>(
         event_loop: &winit::event_loop::EventLoopWindowTarget<E>,
         gl: std::sync::Arc<glow::Context>,
+        shader_version: Option<ShaderVersion>,
     ) -> Self {
-        let painter = crate::Painter::new(gl, None, "")
+        let painter = crate::Painter::new(gl, None, "", shader_version)
             .map_err(|error| {
                 tracing::error!("error occurred in initializing painter:\n{}", error);
             })

examples/retained_image/src/main.rs

@@ -8,6 +8,7 @@ fn main() {
         initial_window_size: Some(egui::vec2(500.0, 900.0)),
         ..Default::default()
     };
+
     eframe::run_native(
         "Show an image with eframe/egui",
         options,