🔧 Pass window padding to the shaders

docs/how-to-create-new-effects.md

@@ -92,6 +92,7 @@ Please study this code carefully, all of it is explained with inline comments.
 // float     uProgress:   A value which transitions from 0 to 1 during the entire animation.
 // float     uTime:       A steadily increasing value in seconds.
 // vec2      uSize:       The size of uTexture in pixels.
+// float     uPadding:    The empty area around the actual window (e.g. where the shadow is drawn).
 #include "common/uniforms.glsl"
 
 // The width of the fading effect is loaded from the settings.

resources/shaders/common/edgeMask.glsl

@@ -11,11 +11,22 @@ float getEdgeMask(vec2 uv, vec2 maxUV, float fadeWidth) {
   return mask;
 }
 
-float getAbsoluteEdgeMask(float fadePixels) {
-  vec2 uv = cogl_tex_coord_in[0].st * uSize;
-  return getEdgeMask(uv, uSize, fadePixels);
+// Returns an edge mask which fades to zero at the boundaries of the actor. The width of
+// the fade zone is given in pixels. This uses the standard uniforms uSize and uPadding.
+// This means that the fading zone is not actually at the actors boundaries but at the
+// position of the window border in the texture.
+// The offset paramter controls whether the fading is placed inside the window borders
+// (offset = 0), ontop the window borders (offset = 0.5) or outside the window borders
+// (offset = 1).
+float getAbsoluteEdgeMask(float fadePixels, float offset) {
+  float padding = max(0, uPadding - fadePixels * offset);
+  vec2 uv       = cogl_tex_coord_in[0].st * uSize - padding;
+  return getEdgeMask(uv, uSize - 2.0 * padding, fadePixels);
 }
 
+// Returns an edge mask which fades to zero at the boundaries of the actor. The width of
+// the fade zone is given relative to the actor size. This neither uses uSize and
+// uPadding.
 float getRelativeEdgeMask(float fadeAmount) {
   vec2 uv = cogl_tex_coord_in[0].st;
   return getEdgeMask(uv, vec2(1.0), fadeAmount);

resources/shaders/common/uniforms.glsl

@@ -4,8 +4,10 @@
 // uProgress:   A value which transitions from 0 to 1 during the entire animation.
 // uTime:       A steadily increasing value in seconds.
 // uSize:       The size of uTexture in pixels.
+// uPadding:    The empty area around the actual window (e.g. where the shadow is drawn).
 uniform bool uForOpening;
 uniform sampler2D uTexture;
 uniform float uProgress;
 uniform float uTime;
-uniform vec2 uSize;
+uniform vec2 uSize;
+uniform float uPadding;

resources/shaders/energize-a.glsl

@@ -30,7 +30,7 @@ vec2 getMasks(float progress) {
   atomMask *= smoothstep(1.0, 0.0, fadeOutProgress);
 
   // Fade-out the masks at the window edges.
-  float edgeFade = getAbsoluteEdgeMask(EDGE_FADE_WIDTH);
+  float edgeFade = getAbsoluteEdgeMask(EDGE_FADE_WIDTH, 0.5);
   atomMask *= edgeFade;
 
   float heartMask = getRelativeEdgeMask(0.5);

resources/shaders/energize-b.glsl

@@ -47,7 +47,7 @@ vec4 getMasks(float progress) {
   streakMask = max(streakMask, showerMask);
 
   // Fade-out the masks at the window edges.
-  float edgeFade = getAbsoluteEdgeMask(EDGE_FADE);
+  float edgeFade = getAbsoluteEdgeMask(EDGE_FADE, 0.5);
   streakMask *= edgeFade;
   showerMask *= edgeFade;
 

resources/shaders/fire.glsl

@@ -72,7 +72,7 @@ vec2 effectMask(float hideTime, float fadeWidth, float edgeFadeWidth) {
   }
 
   // Fade at window borders.
-  effectMask *= getAbsoluteEdgeMask(edgeFadeWidth);
+  effectMask *= getAbsoluteEdgeMask(edgeFadeWidth, 0.5);
 
   if (uForOpening) {
     windowMask = 1.0 - windowMask;

resources/shaders/matrix.glsl

@@ -52,7 +52,7 @@ vec2 getRain(vec2 fragCoord) {
   float windowAlpha = 1 - clamp(uSize.y * distToDrop, 0, FADE_WIDTH) / FADE_WIDTH;
 
   // Fade at window borders.
-  rainAlpha *= getAbsoluteEdgeMask(EDGE_FADE);
+  rainAlpha *= getAbsoluteEdgeMask(EDGE_FADE, 0.5);
 
   // Add some variation to the drop start and end position.
   float shorten =

src/Shader.js

@@ -70,10 +70,17 @@ var Shader = GObject.registerClass(
       this._uProgress   = this.get_uniform_location('uProgress');
       this._uTime       = this.get_uniform_location('uTime');
       this._uSize       = this.get_uniform_location('uSize');
+      this._uPadding    = this.get_uniform_location('uPadding');
     }
 
     // This is called once each time the shader is used.
     beginAnimation(settings, forOpening, actor) {
+
+      // This is not necessarily symmetric, but I haven't figured out a way to
+      // get the actual values...
+      const padding = (actor.width - actor.meta_window.get_frame_rect().width) / 2;
+
+      this.set_uniform_float(this._uPadding, 1, [padding]);
       this.set_uniform_float(this._uForOpening, 1, [forOpening]);
       this.set_uniform_float(this._uSize, 2, [actor.width, actor.height]);