CameraFrame shader chunks can be overwritten

src/extras/render-passes/camera-frame.js

@@ -171,6 +171,26 @@ import { CameraFrameOptions, RenderPassCameraFrame } from './render-pass-camera-
  * Implementation of a simple to use camera rendering pass, which supports SSAO, Bloom and
  * other rendering effects.
  *
+ * Overriding compose shader chunks:
+ * The final compose pass registers its shader chunks in a way that does not override any chunks
+ * that were already provided. To customize the compose pass output, set your shader chunks on the
+ * {@link ShaderChunks} map before creating the `CameraFrame`. Those chunks will be picked up by
+ * the compose pass and preserved.
+ *
+ * Example (GLSL):
+ *
+ * @example
+ * // Provide custom compose chunk(s) before constructing CameraFrame
+ * ShaderChunks.get(graphicsDevice, SHADERLANGUAGE_GLSL).set('composeVignettePS', `
+ *     #ifdef VIGNETTE
+ *         vec3 applyVignette(vec3 color, vec2 uv) {
+ *             return color * uv.u;
+ *         }
+ *     #endif
+ * `);
+ *
+ * // For WebGPU, use SHADERLANGUAGE_WGSL instead.
+ *
  * @category Graphics
  */
 class CameraFrame {

src/extras/render-passes/render-pass-compose.js

@@ -82,8 +82,8 @@ class RenderPassCompose extends RenderPassShaderQuad {
         super(graphicsDevice);
 
         // register compose shader chunks
-        ShaderChunks.get(graphicsDevice, SHADERLANGUAGE_GLSL).add(composeChunksGLSL);
-        ShaderChunks.get(graphicsDevice, SHADERLANGUAGE_WGSL).add(composeChunksWGSL);
+        ShaderChunks.get(graphicsDevice, SHADERLANGUAGE_GLSL).add(composeChunksGLSL, false);
+        ShaderChunks.get(graphicsDevice, SHADERLANGUAGE_WGSL).add(composeChunksWGSL, false);
 
         const { scope } = graphicsDevice;
         this.sceneTextureId = scope.resolve('sceneTexture');

src/scene/shader-lib/shader-chunk-map.js

@@ -33,11 +33,14 @@ class ShaderChunkMap extends Map {
      * same name already exists, the element will be updated.
      *
      * @param {Object} object - Object containing shader chunks.
+     * @param {boolean} override - Whether to override existing shader chunks. Defaults to true.
      * @returns {this} The ShaderChunkMap instance.
      */
-    add(object) {
+    add(object, override = true) {
         for (const [key, value] of Object.entries(object)) {
-            this.set(key, value);
+            if (override || !this.has(key)) {
+                this.set(key, value);
+            }
         }
         return this;
     }