particle fading shader

src/shaders/alphadither.frag

@@ -0,0 +1,55 @@
+/**
+ * Blue Noise texture created by Christoph Peters, released under CC0
+ * http://momentsingraphics.de/BlueNoise.html
+ */
+
+
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+
+vec4 gammaIn(vec4 col) {
+    return pow(col, vec4(2.2));
+}
+
+vec4 gammaOut(vec4 col) {
+    return pow(col, vec4(1.0 / 2.2));
+}
+
+in vec4 v_color;
+in vec2 v_texCoords;
+
+uniform sampler2D u_texture;
+uniform sampler2D u_pattern;
+uniform ivec2 rnd = ivec2(0,0);
+uniform mat4 swizzler = mat4(
+1.0,0.0,0.0,0.0,
+0.0,1.0,0.0,0.0,
+0.0,0.0,1.0,0.0,
+0.0,0.0,0.0,1.0
+);
+uniform float quant = 1.0; // 64 steps -> 63.0; 256 steps -> 255.0
+
+vec4 quantVec = vec4(quant);
+vec4 invQuant = vec4(1.0 / quant);
+
+out vec4 fragColor;
+
+const vec2 boolean = vec2(0.0, 1.0);
+const vec2 patternsize = vec2(1.0/512.0, 1.0/512.0);
+
+
+float nearestAlpha(float alpha) {
+    return min(1.0, max(0.0, floor(alpha + 0.5)));
+}
+
+void main(void) {
+    vec4 particleCol = vec4(v_color.rgb, smoothstep(0.0, 1.0, v_color.a));
+    vec4 inColor = particleCol * texture(u_texture, v_texCoords);
+
+    float bayerThreshold = (swizzler * vec4(texture(u_pattern, (gl_FragCoord.xy + rnd) * patternsize))).r;
+    float alpha = nearestAlpha((inColor.a * 256.0 / 255.0) - (1.0 / 255.0) + (bayerThreshold - 0.5));
+
+    fragColor = inColor * boolean.yyyx + alpha * boolean.xxxy;
+}