74 lines
2.3 KiB
Plaintext
74 lines
2.3 KiB
Plaintext
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#version 450 core
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#extension GL_GOOGLE_include_directive : enable
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#include "lib/common.glsl"
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IN(0, vec2, texcoord)
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OUT(0, float, ssao)
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#define KERNEL_SIZE 32
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layout (std140, binding = 0) uniform Params {
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mat4 Projection;
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vec4 Kernel[KERNEL_SIZE];
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int Samples;
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float Scale;
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float Radius;
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float Bias;
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float Power;
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};
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SAMPLER(1, position)
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SAMPLER(2, normal)
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SAMPLER(3, noise)
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void main()
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{
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vec2 noiseSize = vec2(textureSize(tex_noise, 0));
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vec2 outputSize = vec2(textureSize(tex_position, 0)) / Scale;
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vec2 noiseScale = outputSize / noiseSize;
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// get input vectors from gbuffer & noise texture
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vec3 fragPos = texture(tex_position, in_texcoord).xyz;
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vec3 normalEncoded = texture(tex_normal, in_texcoord).xyz;
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vec3 normal = unpack_normal(normalEncoded);
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// discard gbuffer entries without normal data
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if (normalEncoded == vec3(0)) {
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out_ssao = 1;
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return;
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}
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vec3 randomVec = texture(tex_noise, in_texcoord * noiseScale).xyz;
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// create TBN change-of-basis matrix: from tangent-space to view-space
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vec3 tangent = normalize(randomVec - normal * dot(randomVec, normal));
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vec3 bitangent = cross(normal, tangent);
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mat3 TBN = mat3(tangent, bitangent, normal);
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// iterate over the sample kernel and calculate occlusion factor
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float occlusion = 0.0;
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for(int i = 0; i < Samples; ++i)
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{
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// get sample position
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vec3 sampleVec = TBN * Kernel[i].xyz; // from tangent to view-space
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sampleVec = fragPos + sampleVec * Radius;
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// project sample position (to sample texture) (to get position on screen/texture)
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vec4 offset = vec4(sampleVec, 1.0);
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offset = Projection * offset; // from view to clip-space
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offset.xyz /= offset.w; // perspective divide, clip -> NDC
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offset.xyz = offset.xyz * 0.5 + 0.5; // transform to range 0.0 - 1.0
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// get sample depth - i.e. the Z component of the sampled position in view space
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float sampleDepth = texture(tex_position, offset.xy).z;
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// range check & accumulate
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float rangeCheck = smoothstep(0.0, 1.0, Radius / abs(fragPos.z - sampleDepth));
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occlusion += (sampleDepth <= sampleVec.z - Bias ? 1.0 : 0.0) * rangeCheck;
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}
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occlusion = 1.0 - (occlusion / Samples);
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occlusion = pow(occlusion, Power);
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out_ssao = occlusion;
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}
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