90 lines
2.8 KiB
GLSL
90 lines
2.8 KiB
GLSL
#version 450
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const uint NUM_SAMPLES = 64;
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const uint NUM_ROTATIONS = 16;
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const int ROTATION_KERNEL_W = 4;
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const int ROTATION_KERNEL_H = 4;
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// can perhaps pass in as push constant.
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const float RADIUS = 0.5f;
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const float BIAS = 0.005f;
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layout(local_size_x = 16, local_size_y = 16) in;
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layout(set = 4, binding = 0, rgba32f) uniform image2D positions;
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layout(set = 4, binding = 1, rgba32f) uniform image2D normals;
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layout(set = 4, binding = 2, rgba32f) uniform image2D outputImage;
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// SSAO data
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layout(std430, set = 5, binding = 0) buffer SSAOData
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{
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vec4 samples[NUM_SAMPLES];
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} ssaoData;
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layout (set = 5, binding = 1) uniform sampler2D noiseTexture;
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layout(set = 2, binding = 0) uniform CameraData
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{
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vec4 position;
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mat4 vpMat;
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mat4 viewMat;
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mat4 projMat;
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} cameraData;
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void main()
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{
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ivec2 size = imageSize (outputImage);
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ivec2 globalThread = ivec2 (gl_GlobalInvocationID.xy);
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// load all the necessary variables
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vec3 viewSpacePos = imageLoad (positions, globalThread).rgb;
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vec3 viewSpaceNormal = normalize (imageLoad (normals, globalThread).rgb);
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viewSpaceNormal = -viewSpaceNormal;
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ivec2 noiseDim = textureSize(noiseTexture, 0);
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vec2 threadUV = (vec2(globalThread) + vec2 (0.5f)) / vec2(size);
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vec2 noiseUVMult = vec2 (float(size.x)/float(noiseDim.x), float(size.y) / float(noiseDim.y));
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noiseUVMult *= threadUV;
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vec3 randomVec = texture(noiseTexture, noiseUVMult).rgb * 2.0f - 1.0f;
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// Gram schmidt
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vec3 tangent = normalize (randomVec - (viewSpaceNormal * dot(viewSpaceNormal, randomVec)));
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vec3 bitangent = cross (viewSpaceNormal, tangent);
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// matrix for tangent to view
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mat3 TBN = mat3(tangent, bitangent, viewSpaceNormal);
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float occlusion = 0.0f;
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for (int i = 0; i < NUM_SAMPLES; ++i)
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{
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// We want to get a position at an offset from the view space position. Offset scaled by radius.
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vec3 samplePos = TBN * ssaoData.samples[i].rgb;
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samplePos = viewSpacePos + samplePos * RADIUS;
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// Now we take that offset position and bring it to clip space
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vec4 offsetPos = vec4 (samplePos, 1.0f);
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offsetPos = cameraData.projMat * offsetPos;
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// then we do perspective division
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offsetPos.xyz /= offsetPos.w;
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// and bring it from [-1, 1] to screen coordinates
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offsetPos.xyz = ((offsetPos.xyz * 0.5f) + 0.5f);
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offsetPos.xy *= vec2(size.xy);
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//offsetPos.y = size.y - offsetPos.y;
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float sampleDepth = imageLoad (positions, ivec2 (offsetPos.xy)).z;
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float rangeCheck = smoothstep (0.0f, 1.0f, RADIUS / abs (viewSpacePos.z - sampleDepth));
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occlusion += (sampleDepth >= samplePos.z + BIAS ? 1.0f : 0.0f) * rangeCheck;
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}
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occlusion = 1.0f - (occlusion / float(NUM_SAMPLES));
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// store result into result image
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imageStore(outputImage, ivec2(gl_GlobalInvocationID.xy), vec4(occlusion.rrr, 0.0f));
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} |