🔨 Initial attempt on window-opening animation

src/EnergizeB.js

@@ -74,15 +74,23 @@ var EnergizeB = class EnergizeB {
   // ---------------------------------------------------------------- API for extension.js
 
   // This is called from extension.js whenever a window is closed with this effect.
-  static createShader(actor, settings) {
-    return new Shader(settings);
+  static createShader(actor, settings, forOpening) {
+    return new Shader(settings, forOpening);
   }
 
-  // This is also called from extension.js. It is used to tweak the ongoing transition of
-  // the actor - usually windows are faded to transparency and scaled down slightly by
-  // GNOME Shell. For this effect, windows should neither be scaled nor faded.
-  static getCloseTransition(actor, settings) {
-    return {'opacity': {to: 255}, 'scale-x': {to: 1.0}, 'scale-y': {to: 1.0}};
+  // This is also called from extension.js. It is used to tweak a window's open / close
+  // transitions - usually windows are faded in / out and scaled up / down by GNOME Shell.
+  // forOpening is set to true if this is called for a window-open transition, for a
+  // window-close transition it is set to false. The modes can be set to any value from
+  // here: https://gjs-docs.gnome.org/clutter8~8_api/clutter.animationmode. This also
+  // determines how the uProgress uniform value will progress in the shader.
+  // For this effect, windows should neither be scaled nor faded.
+  static tweakTransition(actor, settings, forOpening) {
+    return {
+      'opacity': {from: 255, to: 255, mode: 3},
+      'scale-x': {from: 1.0, to: 1.0, mode: 3},
+      'scale-y': {from: 1.0, to: 1.0, mode: 3}
+    };
   }
 }
 
@@ -99,7 +107,7 @@ if (utils.isInShellProcess()) {
   const shaderSnippets = Me.imports.src.shaderSnippets;
 
   Shader = GObject.registerClass({}, class Shader extends Clutter.ShaderEffect {
-    _init(settings) {
+    _init(settings, forOpening) {
       super._init({shader_type: Clutter.ShaderType.FRAGMENT_SHADER});
 
       const color = Clutter.Color.from_string(settings.get_string('energize-b-color'))[1];
@@ -162,6 +170,10 @@ if (utils.isInShellProcess()) {
         // Compute fading window opacity.
         float windowMask = pow(1.0 - fadeProgress, 2.0);
 
+        #if ${forOpening ? '1' : '0'}
+          windowMask = 1.0 - windowMask;
+        #endif
+
         return vec4(showerMask, streakMask, atomMask, windowMask);
       }