🔧 Convert window texture alpha from premultiplied to straight

src/BrokenGlass.js

@@ -213,7 +213,7 @@ if (utils.isInShellProcess()) {
       freeShaders.push(this);
     }
 
-    // This is called by the constructor. This is means it's only called when the effect
+    // This is called by the constructor. This means, it's only called when the effect
     // is used for the first time.
     vfunc_build_pipeline() {
       const declarations = `
@@ -277,6 +277,11 @@ if (utils.isInShellProcess()) {
             cogl_color_out = texture2D(uTexture, coords);
           }
         }
+
+        // Shell.GLSLEffect uses straight alpha. So we have to convert from premultiplied.
+        if (cogl_color_out.a > 0) {
+          cogl_color_out.rgb /= cogl_color_out.a;
+        }
       `;
 
       this.add_glsl_snippet(Shell.SnippetHook.FRAGMENT, declarations, code, true);