Shader cleanup

core/assets/shaders/snow.frag

@@ -0,0 +1,48 @@
+#define LIGHT
+
+#ifdef LIGHT
+    #define LAYERS 30.
+    #define DEPTH .5
+    #define WIDTH .3
+    #define SPEED .6
+    #define SIZE 0.2
+#else
+    #define LAYERS 200.
+    #define DEPTH .1
+    #define WIDTH .8
+    #define SPEED 1.5
+    #define SIZE 1.0
+#endif
+
+varying vec2 v_texCoords;
+
+uniform vec2 u_pos;
+uniform vec2 u_resolution;
+uniform float u_time;
+uniform sampler2D u_texture0;
+
+void main(){
+    gl_FragColor = texture2D(u_texture0, v_texCoords);
+
+    vec2 uv = (v_texCoords * u_resolution + u_pos) / 1000.0;
+    const mat3 p = mat3(
+        13.3231, 23.5112, 21.7112,
+        21.1212, 28.7312, 11.9312,
+        21.8112, 14.7212, 61.3934
+    );
+    float dof = 5.*sin(u_time*.1);
+
+    //TODO this is very slow
+    for(float i=0.0; i<LAYERS; i++){
+        vec2 q = uv* (1.+i*DEPTH);
+        q += vec2( q.y* WIDTH *( fract(i*7.238917) - .5 ),
+        SPEED* u_time / (1.+i*DEPTH*.03) );
+        vec3 n = vec3(floor(q), 31.189+i), m = floor(n)/1e5 + fract(n), mp = (31.9+m) / fract(p*m),
+        r = fract(mp);
+        vec2 s = abs(fract(q)-.5 +.9*r.xy-.45) + .01*abs(2.0*fract(10.*q.yx) - 1.0);
+        float d = .6 * (s.x+s.y) + max(s.x,s.y) -.01,
+        edge = .005*SIZE + .05 * SIZE * min( .5* abs(i-5.-dof), 1.);
+
+        gl_FragColor += smoothstep(edge,-edge,d) * r.x / (1.+.02*i*DEPTH);
+    }
+}