Auto merge of #24242 - jdm:xr-webgllayer-format, r=asajeffrey,nox

Fix immersive mode panic on three.js rollercoaster on hololens

We have some special logic about texture formats when creating drawing buffers for WebGL that needs to be shared with the code that creates a separate framebuffer for immersive mode.

---
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #24083 and fix #20595.
- [x] These changes do not require tests because no CI for hololens; tested manually in the emulator.

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components/canvas/gl_context.rs

@@ -4,14 +4,14 @@
 
 use super::webgl_thread::{GLState, WebGLImpl};
 use canvas_traits::webgl::{
-    GLContextAttributes, GLLimits, WebGLCommand, WebGLCommandBacktrace, WebGLVersion,
+    GLContextAttributes, GLFormats, GLLimits, WebGLCommand, WebGLCommandBacktrace, WebGLVersion,
 };
 use euclid::default::Size2D;
 use offscreen_gl_context::{
     ColorAttachmentType, DrawBuffer, GLContext, GLContextAttributes as RawGLContextAttributes,
     GLContextDispatcher,
 };
-use offscreen_gl_context::{GLLimits as RawGLLimits, GLVersion};
+use offscreen_gl_context::{GLFormats as RawGLFormats, GLLimits as RawGLLimits, GLVersion};
 use offscreen_gl_context::{NativeGLContext, NativeGLContextHandle, NativeGLContextMethods};
 use offscreen_gl_context::{OSMesaContext, OSMesaContextHandle};
 use sparkle::gl;
@@ -179,7 +179,7 @@ impl GLContextWrapper {
         }
     }
 
-    pub fn get_info(&self) -> (Size2D<i32>, u32, GLLimits) {
+    pub fn get_info(&self) -> (Size2D<i32>, u32, GLLimits, GLFormats) {
         match *self {
             GLContextWrapper::Native(ref ctx) => {
                 let (real_size, texture_id) = {
@@ -191,8 +191,9 @@ impl GLContextWrapper {
                 };
 
                 let limits = ctx.borrow_limits().clone();
+                let formats = map_formats(ctx.borrow_formats());
 
-                (real_size, texture_id, map_limits(limits))
+                (real_size, texture_id, map_limits(limits), formats)
             },
             GLContextWrapper::OSMesa(ref ctx) => {
                 let (real_size, texture_id) = {
@@ -204,8 +205,9 @@ impl GLContextWrapper {
                 };
 
                 let limits = ctx.borrow_limits().clone();
+                let formats = map_formats(ctx.borrow_formats());
 
-                (real_size, texture_id, map_limits(limits))
+                (real_size, texture_id, map_limits(limits), formats)
             },
         }
     }
@@ -260,3 +262,10 @@ pub fn map_attrs_to_script_attrs(attrs: RawGLContextAttributes) -> GLContextAttr
         preserve_drawing_buffer: attrs.preserve_drawing_buffer,
     }
 }
+
+fn map_formats(formats: &RawGLFormats) -> GLFormats {
+    GLFormats {
+        texture_format: formats.texture,
+        texture_type: formats.texture_type,
+    }
+}

components/canvas/webgl_thread.rs

@@ -238,7 +238,7 @@ impl WebGLThread {
             WebGLMsg::CreateContext(version, size, attributes, result_sender) => {
                 let result = self.create_webgl_context(version, size, attributes);
                 result_sender
-                    .send(result.map(|(id, limits, share_mode)| {
+                    .send(result.map(|(id, limits, share_mode, framebuffer_format)| {
                         let data = Self::make_current_if_needed(
                             id,
                             &self.contexts,
@@ -276,6 +276,7 @@ impl WebGLThread {
                             share_mode,
                             glsl_version,
                             api_type,
+                            framebuffer_format,
                         }
                     }))
                     .unwrap();
@@ -406,7 +407,7 @@ impl WebGLThread {
         version: WebGLVersion,
         size: Size2D<u32>,
         attributes: GLContextAttributes,
-    ) -> Result<(WebGLContextId, GLLimits, WebGLContextShareMode), String> {
+    ) -> Result<(WebGLContextId, GLLimits, WebGLContextShareMode, GLFormats), String> {
         // Creating a new GLContext may make the current bound context_id dirty.
         // Clear it to ensure that  make_current() is called in subsequent commands.
         self.bound_context_id = None;
@@ -434,7 +435,7 @@ impl WebGLThread {
                 .next_id(WebrenderImageHandlerType::WebGL)
                 .0 as usize,
         );
-        let (size, texture_id, limits) = ctx.get_info();
+        let (size, texture_id, limits, framebuffer_formats) = ctx.get_info();
         let use_apple_vertex_arrays = needs_apple_vertex_arrays(ctx.gl(), version);
         self.contexts.insert(
             id,
@@ -458,7 +459,7 @@ impl WebGLThread {
             },
         );
 
-        Ok((id, limits, share_mode))
+        Ok((id, limits, share_mode, framebuffer_formats))
     }
 
     /// Resizes a WebGLContext
@@ -476,7 +477,7 @@ impl WebGLThread {
         .expect("Missing WebGL context!");
         match data.ctx.resize(size) {
             Ok(old_draw_buffer) => {
-                let (real_size, texture_id, _) = data.ctx.get_info();
+                let (real_size, texture_id, _, _) = data.ctx.get_info();
                 let info = self.cached_context_info.get_mut(&context_id).unwrap();
                 if let ContextRenderState::Locked(ref mut in_use) = info.render_state {
                     // If there's already an outdated draw buffer present, we can ignore