export default "#define SAMPLE_NUMBER 1024\n#define PI 3.14159265358979\nuniform mat4 viewInverse : VIEWINVERSE;\nuniform samplerCube environmentMap;\nuniform sampler2D normalDistribution;\nuniform float roughness : 0.5;\nvarying vec2 v_Texcoord;\nvarying vec3 v_WorldPosition;\nconst float fSampleNumber = float(SAMPLE_NUMBER);\n@import clay.util.rgbm\nvec3 importanceSampleNormal(float i, float roughness, vec3 N) {\n vec3 H = texture2D(normalDistribution, vec2(roughness, i)).rgb;\n vec3 upVector = abs(N.z) < 0.999 ? vec3(0.0, 0.0, 1.0) : vec3(1.0, 0.0, 0.0);\n vec3 tangentX = normalize(cross(upVector, N));\n vec3 tangentY = cross(N, tangentX);\n return tangentX * H.x + tangentY * H.y + N * H.z;\n}\nvoid main() {\n vec3 eyePos = viewInverse[3].xyz;\n vec3 V = normalize(v_WorldPosition - eyePos);\n vec3 N = V;\n vec3 R = V;\n vec3 prefilteredColor = vec3(0.0);\n float totalWeight = 0.0;\n for (int i = 0; i < SAMPLE_NUMBER; i++) {\n vec3 H = importanceSampleNormal(float(i) / fSampleNumber, roughness, N);\n vec3 L = reflect(-V, H);\n float NoL = clamp(dot(N, L), 0.0, 1.0);\n if (NoL > 0.0) {\n prefilteredColor += decodeHDR(textureCube(environmentMap, L)).rgb * NoL;\n totalWeight += NoL;\n }\n }\n gl_FragColor = encodeHDR(vec4(prefilteredColor / totalWeight, 1.0));\n}\n";
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