🎉 Add doom effect

src/Doom.js

@@ -0,0 +1,110 @@
+//////////////////////////////////////////////////////////////////////////////////////////
+//          )                                                   (                       //
+//       ( /(   (  (               )    (       (  (  (         )\ )    (  (            //
+//       )\()) ))\ )(   (         (     )\ )    )\))( )\  (    (()/( (  )\))(  (        //
+//      ((_)\ /((_|()\  )\ )      )\  '(()/(   ((_)()((_) )\ )  ((_)))\((_)()\ )\       //
+//      | |(_|_))( ((_)_(_/(    _((_))  )(_))  _(()((_|_)_(_/(  _| |((_)(()((_|(_)      //
+//      | '_ \ || | '_| ' \))  | '  \()| || |  \ V  V / | ' \)) _` / _ \ V  V (_-<      //
+//      |_.__/\_,_|_| |_||_|   |_|_|_|  \_, |   \_/\_/|_|_||_|\__,_\___/\_/\_//__/      //
+//                                 |__/                                                 //
+//                       Copyright (c) 2021 Simon Schneegans                            //
+//          Released under the GPLv3 or later. See LICENSE file for details.            //
+//////////////////////////////////////////////////////////////////////////////////////////
+
+'use strict';
+
+const GObject = imports.gi.GObject;
+
+const _ = imports.gettext.domain('burn-my-windows').gettext;
+
+const ExtensionUtils = imports.misc.extensionUtils;
+const Me             = imports.misc.extensionUtils.getCurrentExtension();
+const utils          = Me.imports.src.utils;
+const ShaderFactory  = Me.imports.src.ShaderFactory.ShaderFactory;
+
+//////////////////////////////////////////////////////////////////////////////////////////
+// This effect melts your windows. Inspired by the legendary screen transitions of the  //
+// original Doom.                                                                       //
+//////////////////////////////////////////////////////////////////////////////////////////
+
+// The effect class can be used to get some metadata (like the effect's name or supported
+// GNOME Shell versions), to initialize the respective page of the settings dialog, as
+// well as to create the actual shader for the effect.
+var Doom = class {
+
+  // The constructor creates a ShaderFactory which will be used by extension.js to create
+  // shader instances for this effect. The shaders will be automagically created using the
+  // GLSL file in resources/shaders/<nick>.glsl. The callback will be called for each
+  // newly created shader instance.
+  constructor() {
+    this.shaderFactory = new ShaderFactory(this.getNick(), (shader) => {
+      // Store uniform locations of newly created shaders.
+      shader._uActorScale      = shader.get_uniform_location('uActorScale');
+      shader._uHorizontalScale = shader.get_uniform_location('uHorizontalScale');
+      shader._uVerticalScale   = shader.get_uniform_location('uVerticalScale');
+      shader._uPixelSize       = shader.get_uniform_location('uPixelSize');
+
+      // Write all uniform values at the start of each animation.
+      shader.connect('begin-animation', (shader, settings, forOpening, actor) => {
+        let actorScale = 2.0 * Math.max(1.0, global.stage.height / actor.height);
+        // clang-format off
+        shader.set_uniform_float(shader._uActorScale,      1, [actorScale]);
+        shader.set_uniform_float(shader._uHorizontalScale, 1, [settings.get_double('doom-horizontal-scale')]);
+        shader.set_uniform_float(shader._uVerticalScale,   1, [settings.get_double('doom-vertical-scale')]);
+        shader.set_uniform_float(shader._uPixelSize,       1, [settings.get_double('doom-pixel-size')]);
+        // clang-format on
+      });
+    });
+  }
+
+  // ---------------------------------------------------------------------------- metadata
+
+  // The effect is not available on GNOME Shell 3.36 as it requires scaling of the window
+  // actor.
+  getMinShellVersion() {
+    return [3, 38];
+  }
+
+  // This will be called in various places where a unique identifier for this effect is
+  // required. It should match the prefix of the settings keys which store whether the
+  // effect is enabled currently (e.g. '*-close-effect'), and its animation time
+  // (e.g. '*-animation-time').
+  getNick() {
+    return 'doom';
+  }
+
+  // This will be shown in the sidebar of the preferences dialog as well as in the
+  // drop-down menus where the user can choose the effect.
+  getLabel() {
+    return _('Doom');
+  }
+
+  // -------------------------------------------------------------------- API for prefs.js
+
+  // This is called by the preferences dialog. It loads the settings page for this effect,
+  // and binds all properties to the settings.
+  getPreferences(dialog) {
+
+    // Add the settings page to the builder.
+    dialog.getBuilder().add_from_resource(`/ui/${utils.getGTKString()}/Doom.ui`);
+
+    // Bind all properties.
+    dialog.bindAdjustment('doom-animation-time');
+    dialog.bindAdjustment('doom-horizontal-scale');
+    dialog.bindAdjustment('doom-vertical-scale');
+    dialog.bindAdjustment('doom-pixel-size');
+
+    // Finally, return the new settings page.
+    return dialog.getBuilder().get_object('doom-prefs');
+  }
+
+  // ---------------------------------------------------------------- API for extension.js
+
+  // The getActorScale() is called from extension.js to adjust the actor's size during the
+  // animation. This is useful if the effect requires drawing something beyond the usual
+  // bounds of the actor. This only works for GNOME 3.38+.
+  getActorScale(settings, actor) {
+    let actorScale = 2.0 * Math.max(1.0, global.stage.height / actor.height);
+    return {x: 1.0, y: actorScale};
+  }
+}