40 lines
1.0 KiB
Plaintext
40 lines
1.0 KiB
Plaintext
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mat3 getTangentSpace(vec3 normal)
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{
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vec3 helper = abs(normal.x) > 0.99
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? vec3(1.0,0.0,0.0)
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: vec3(0.0,0.0,1.0);
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vec3 tangent = normalize(cross(normal, helper));
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vec3 binormal = normalize(cross(normal, tangent));
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return mat3(tangent, binormal, normal);
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}
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vec3 sampleHemisphere(vec3 normal)
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{
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vec2 uv = pixelUv();
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uv += _seed.xy;
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vec4 noise = sampleNoise(uv);;
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float cosTheta = random(normalize(normal.xy+noise.xy));
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float sinTheta = sqrt(max(0.0,1.0-cosTheta*cosTheta));
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float phi = 2.0*PI*random(normalize(normal.yz+noise.xw));
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vec3 tangentSpaceDir = vec3(cos(phi)*sinTheta, sin(phi)*sinTheta, cosTheta);
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// convert direction from tangent space to world space
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mat3 ts = getTangentSpace(normal);
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return ts * tangentSpaceDir;
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}
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vec3 scatterLambert(inout Ray ray, RayHit hit)
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{
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ray.origin = hit.position + hit.normal*0.001;
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ray.direction = sampleHemisphere(hit.normal);
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ray.energy *= 2.0 * hit.albedo * sdot(hit.normal, ray.direction);
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return vec3(0.0);
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}
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