SuperTuxKart 1.5 upstream source (from official release tarball)

data/shaders/godray.frag

@@ -0,0 +1,32 @@
+uniform sampler2D tex;
+uniform vec2 sunpos;
+
+#define SAMPLES 12
+
+const float decaystep = 0.88;
+
+out vec4 FragColor;
+
+void main()
+{
+	vec2 uv = 4. * gl_FragCoord.xy / u_screen;
+	vec2 texc = uv;
+	vec2 tosun = sunpos - texc;
+
+//	if (dot(tosun, tosun) > 0.49) discard;
+
+	vec2 dist = tosun * 1.0/(float(SAMPLES) * 1.12);
+
+	vec3 col = texture(tex, texc).xyz;
+	float decay = 1.0;
+
+	for (int i = 0; i < SAMPLES; i++) {
+		texc += dist;
+		vec3 here = texture(tex, texc).xyz;
+		here *= decay;
+		col += here;
+		decay *= decaystep;
+	}
+
+	FragColor = vec4(col, 1.0) * 0.8;
+}