SuperTuxKart 1.5 upstream source (from official release tarball)

data/shaders/importance_sampling_specular.frag

@@ -0,0 +1,34 @@
+uniform samplerCube tex;
+uniform sampler2D samples;
+uniform float ViewportSize;
+
+uniform mat4 PermutationMatrix;
+
+out vec4 FragColor;
+
+void main(void)
+{
+    vec2 uv = gl_FragCoord.xy / ViewportSize;
+    vec3 RayDir = 2. * vec3(uv, 1.) - 1.;
+    RayDir = normalize((PermutationMatrix * vec4(RayDir, 0.)).xyz);
+
+    vec4 FinalColor = vec4(0.);
+    vec3 up = (RayDir.y < .99) ? vec3(0., 1., 0.) : vec3(0., 0., 1.);
+    vec3 Tangent = normalize(cross(up, RayDir));
+    vec3 Bitangent = cross(RayDir, Tangent);
+    float weight = 0.;
+
+    for (int i = 0; i < 1024; i++)
+    {
+        vec2 texel = texelFetch(samples, ivec2(i, 0), 0).rg;
+        float Theta = texel.r;
+        float Phi = texel.g;
+
+        vec3 L = cos(Theta) * RayDir + sin(Theta) * cos(Phi) * Tangent + sin(Theta) * sin(Phi) * Bitangent;
+        float NdotL = clamp(dot(RayDir, L), 0., 1.);
+        FinalColor += textureLod(tex, L, 0.) * NdotL;
+        weight += NdotL;
+    }
+
+    FragColor = FinalColor / weight;
+}