🔧 Tweak shader

src/Incinerate.js

@@ -37,12 +37,20 @@ var Incinerate = class {
   // newly created shader instance.
   constructor() {
     this.shaderFactory = new ShaderFactory(this.getNick(), (shader) => {
-      // We import Clutter in this function as it is not available in the preferences
-      // process. This creator function of the ShaderFactory is only called within GNOME
-      // Shell's process.
-      const Clutter = imports.gi.Clutter;
+      // We import these modules in this function as they are not available in the
+      // preferences process. This callback is only called within GNOME Shell's process.
+      const {Clutter, GdkPixbuf, Cogl} = imports.gi;
+
+      // Create the texture in the first call.
+      if (!this._ashTexture) {
+        const ashData    = GdkPixbuf.Pixbuf.new_from_resource('/img/dust.png');
+        this._ashTexture = new Clutter.Image();
+        this._ashTexture.set_data(ashData.get_pixels(), Cogl.PixelFormat.RGB_888,
+                                  ashData.width, ashData.height, ashData.rowstride);
+      }
 
       // Store uniform locations of newly created shaders.
+      shader._uAshTexture = shader.get_uniform_location('uAshTexture');
       shader._uSeed       = shader.get_uniform_location('uSeed');
       shader._uColor      = shader.get_uniform_location('uColor');
       shader._uWidth      = shader.get_uniform_location('uWidth');
@@ -65,6 +73,23 @@ var Incinerate = class {
         shader.set_uniform_float(shader._uTurbulence, 1, [settings.get_double('incinerate-turbulence')]);
         // clang-format on
       });
+
+      // This is required to bind the ash texture for drawing. Sadly, this seems to be
+      // impossible under GNOME 3.3x as this.get_pipeline() is not available. It was
+      // called get_target() back then but this is not wrapped in GJS.
+      // https://gitlab.gnome.org/GNOME/mutter/-/blob/gnome-3-36/clutter/clutter/clutter-offscreen-effect.c#L598
+      shader.connect('update-animation', (shader) => {
+        const pipeline = shader.get_pipeline();
+
+        // Use linear filtering for the window texture.
+        pipeline.set_layer_filters(0, Cogl.PipelineFilter.LINEAR,
+                                   Cogl.PipelineFilter.LINEAR);
+
+        // Bind the ash texture.
+        pipeline.set_layer_texture(1, this._ashTexture.get_texture());
+        pipeline.set_layer_wrap_mode(1, Cogl.PipelineWrapMode.REPEAT);
+        pipeline.set_uniform_1i(shader._uAshTexture, 1);
+      });
     });
   }