stk-code_catmod/data/shaders/ssao.frag

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// From paper http://graphics.cs.williams.edu/papers/AlchemyHPG11/
// and improvements here http://graphics.cs.williams.edu/papers/SAOHPG12/
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uniform sampler2D ntex;
uniform sampler2D dtex;
uniform sampler2D noise_texture;
uniform vec4 samplePoints[16];
#ifdef UBO_DISABLED
uniform mat4 ViewMatrix;
uniform mat4 ProjectionMatrix;
uniform mat4 InverseViewMatrix;
uniform mat4 InverseProjectionMatrix;
#else
layout (std140) uniform MatrixesData
{
mat4 ViewMatrix;
mat4 ProjectionMatrix;
mat4 InverseViewMatrix;
mat4 InverseProjectionMatrix;
mat4 ShadowViewProjMatrixes[4];
};
#endif
in vec2 uv;
out float AO;
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const float sigma = 1.;
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const float tau = 7.;
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const float beta = 0.0001;
const float epsilon = .00001;
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const float radius = 1.;
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const float k = 1.;
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#define SAMPLES 16
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const float invSamples = 1. / SAMPLES;
vec3 DecodeNormal(vec2 n);
vec4 getPosFromUVDepth(vec3 uvDepth, mat4 InverseProjectionMatrix);
void main(void)
{
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vec4 cur = texture(ntex, uv);
float curdepth = texture(dtex, uv).x;
vec4 FragPos = getPosFromUVDepth(vec3(uv, curdepth), InverseProjectionMatrix);
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// get the normal of current fragment
vec3 ddx = dFdx(FragPos.xyz);
vec3 ddy = dFdy(FragPos.xyz);
vec3 norm = normalize(cross(ddy, ddx));
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// Workaround for nvidia and skyboxes
float len = dot(vec3(1.0), abs(cur.xyz));
if (len < 0.2 || curdepth > 0.9955) discard;
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int x = int(1024. * uv.x), y = int(1024. * uv.y);
float r = radius / FragPos.z;
float phi = 30. * (x ^ y) + 10. * x * y;
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float bl = 0.0;
for(int i = 0; i < SAMPLES; ++i) {
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float alpha = (i + .5) * invSamples;
float theta = 2. * 3.14 * tau * alpha + phi;
float h = r * alpha;
vec2 occluder_uv = h * vec2(cos(theta), sin(theta));
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occluder_uv += uv;
if (occluder_uv.x < 0. || occluder_uv.x > 1. || occluder_uv.y < 0. || occluder_uv.y > 1.) continue;
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float m = round(log2(h)) + 7.;
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float occluderFragmentDepth = textureLod(dtex, occluder_uv, m).x;
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vec4 OccluderPos = getPosFromUVDepth(vec3(occluder_uv, occluderFragmentDepth), InverseProjectionMatrix);
vec3 vi = (OccluderPos - FragPos).xyz;
bl += max(0, dot(vi, norm) - FragPos.z * beta) / (dot(vi, vi) + epsilon);
}
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AO = max(pow(1.0 - 2. * sigma * bl * invSamples, k), 0.);
}