♻️ Use a single GLSL files for each effect

resources/shaders/apparition.glsl

@@ -1,33 +1,49 @@
+// Inject some common shader snippets. It is only possible to include glsl files from the
+// "common" directory. Also, the files in the "common" directory are not allowed to
+// include any further files.
+#include "common/uniforms.glsl"
+
+uniform vec2 uSeed;
+uniform float uShake;
+uniform float uTwirl;
+uniform float uSuction;
+uniform float uRandomness;
+
+const float ACTOR_SCALE = 2.0;
+const float PADDING     = ACTOR_SCALE / 2.0 - 0.5;
+
 // The math for the whirling is inspired by this post:
 // http://www.geeks3d.com/20110428/shader-library-swirl-post-processing-filter-in-glsl
-// We simply inverse the progress for opening windows.
-float progress = uForOpening ? 1.0 - uProgress : uProgress;
+void main() {
+  // We simply inverse the progress for opening windows.
+  float progress = uForOpening ? 1.0 - uProgress : uProgress;
 
-// Choose a random suction center.
-vec2 center = uSeed * uRandomness + 0.5 * (1.0 - uRandomness);
-vec2 coords = cogl_tex_coord_in[0].st * ACTOR_SCALE - PADDING - center;
+  // Choose a random suction center.
+  vec2 center = uSeed * uRandomness + 0.5 * (1.0 - uRandomness);
+  vec2 coords = cogl_tex_coord_in[0].st * ACTOR_SCALE - PADDING - center;
 
-// Add some shaking.
-coords.x +=
-  progress * 0.05 * uShake * sin((progress + uSeed.x) * (1.0 + uSeed.x) * uShake);
-coords.y +=
-  progress * 0.05 * uShake * cos((progress + uSeed.y) * (1.0 + uSeed.y) * uShake);
+  // Add some shaking.
+  coords.x +=
+    progress * 0.05 * uShake * sin((progress + uSeed.x) * (1.0 + uSeed.x) * uShake);
+  coords.y +=
+    progress * 0.05 * uShake * cos((progress + uSeed.y) * (1.0 + uSeed.y) * uShake);
 
-// "Suck" the texture into the center.
-float dist = length(coords) / sqrt(2);
-coords += progress * coords / dist * 0.5 * uSuction;
+  // "Suck" the texture into the center.
+  float dist = length(coords) / sqrt(2);
+  coords += progress * coords / dist * 0.5 * uSuction;
 
-// Apply some whirling.
-float angle = pow(1.0 - dist, 2.0) * uTwirl * progress;
-float s     = sin(angle);
-float c     = cos(angle);
-coords      = vec2(dot(coords, vec2(c, -s)), dot(coords, vec2(s, c)));
+  // Apply some whirling.
+  float angle = pow(1.0 - dist, 2.0) * uTwirl * progress;
+  float s     = sin(angle);
+  float c     = cos(angle);
+  coords      = vec2(dot(coords, vec2(c, -s)), dot(coords, vec2(s, c)));
 
-// Shell.GLSLEffect uses straight alpha. So we have to convert from premultiplied.
-cogl_color_out = texture2D(uTexture, coords + center);
-if (cogl_color_out.a > 0) {
-  cogl_color_out.rgb /= cogl_color_out.a;
-}
+  // Shell.GLSLEffect uses straight alpha. So we have to convert from premultiplied.
+  cogl_color_out = texture2D(uTexture, coords + center);
+  if (cogl_color_out.a > 0) {
+    cogl_color_out.rgb /= cogl_color_out.a;
+  }
 
-// Fade out the window texture.
-cogl_color_out.a *= 1.0 - progress;
+  // Fade out the window texture.
+  cogl_color_out.a *= 1.0 - progress;
+}