Teejoon
110 lines
3.8 KiB
GLSL
110 lines
3.8 KiB
GLSL
#version 430
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//Number of samples per pixel
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uniform int uNumOfSamples;
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//#define uNumOfSamples (11)
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//Number of turns around the cirle
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uniform int uNumOfTurns;
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//#define uNumOfTurns (7)
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layout (binding = 0) uniform sampler2D ViewSpaceZ;
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uniform vec4 uProjInfo;
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uniform float uProjScale;
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//#define ProjScale 500
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uniform float uRadius;
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//#define uRadius 1.0f
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uniform float uBias;
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//#define uBias 0.05f
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uniform float uContrast;
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//#define uContrast 1.5f
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uniform float uIntensityScale;
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//#define uIntensityScale 1.0f
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out float AO;
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vec3 getVSPosition(ivec2 ScreenSpaceCoord) {
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float z = texelFetch(ViewSpaceZ, ScreenSpaceCoord, 0).r;
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//Get the xy view space coordinates and add the z value from ViewSpaceZ buffer.
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return vec3((uProjInfo[0] + (ScreenSpaceCoord.x * uProjInfo[1])) * z, (uProjInfo[2] + (ScreenSpaceCoord.y * uProjInfo[3])) * z, z);
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}
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vec3 getVSFaceNormal(vec3 ViewSpacePosition) {
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// Get tangets vector for the plane and ViewSpacePositin... don't ask how this functions works. It's pure magic.
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// They do this and it just works... I would guess that they approximate the function of a plane from pixels close to the pixel were on now.
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return normalize(cross(dFdx(ViewSpacePosition), dFdy(ViewSpacePosition)));
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}
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vec3 getSampleViewSpacePos(ivec2 ScreenSpaceCoord, int SampleIndex, float RotationAngle, float ScreenSpaceSampleRadius){
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// Pure Magic...
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float alpha = float(SampleIndex) * (1.0 / uNumOfSamples);
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// Angle to where to sample
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float angle = alpha * (uNumOfTurns * 6.28) + RotationAngle;
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//Lenght to were to sample
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ScreenSpaceSampleRadius = ScreenSpaceSampleRadius * alpha;
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vec2 screenSpaceSampleOffsetVecor = vec2(cos(angle), sin(angle));
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// Get texel coordinate on where to sample by going screenSpaceSampleOffsetVecor direction in ScreenSpaceSampleRadius units from ScreenSpaceCoord (the point being shaded);
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ivec2 screenSpaceSampleTexel = ivec2(ScreenSpaceSampleRadius * screenSpaceSampleOffsetVecor) + ScreenSpaceCoord;
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return getVSPosition(screenSpaceSampleTexel);
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}
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float sampleAO(ivec2 ScreenSpaceCoord, vec3 Origin, vec3 OriginNormal, float ScreenSpaceSampleRadius, int SampleIndex, float RotationAngle, float Radius) {
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float radius2 = Radius * Radius;
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vec3 sampleViewSpacePosition = getSampleViewSpacePos(ScreenSpaceCoord, SampleIndex, RotationAngle, ScreenSpaceSampleRadius);
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vec3 sampleVector = Origin - sampleViewSpacePosition;
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// vv = sampleVectorLenght ^ 2
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float vv = dot(sampleVector, sampleVector);
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// vn = angle between sampleVector and Normal
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float vn = dot(sampleVector, OriginNormal);
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const float epsilon = 0.0001f;
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// vv < radius2 if the vector is shorter then the radius;
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// vn - bias, offset the angle to reduse self occlusion.
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// epsilon is here to make divison by 0 impossible.
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return float(vv < radius2) * max((vn - uBias) / (epsilon + vv), 0.0);
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//float f = max(radius2 - vv, 0.0);
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//return f * f * f * max((vn - uBias) / (epsilon + vv), 0.0);
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}
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void main() {
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ivec2 originScreenCoord = ivec2(gl_FragCoord.xy);
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vec3 origin = getVSPosition(originScreenCoord);
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float radius = min(origin.z, uRadius);
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vec3 originNormal = getVSFaceNormal(origin);
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float screenSpaceSampleRadius = -uProjScale * radius / origin.z;
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float rotationAngleOffset = 30 * originScreenCoord.x ^ originScreenCoord.y + 10 * originScreenCoord.x * originScreenCoord.y;
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float sum = 0.0;
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for (int i = 0; i < uNumOfSamples; i++) {
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sum += sampleAO(originScreenCoord, origin, originNormal, screenSpaceSampleRadius, i, rotationAngleOffset, radius);
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}
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//float A = max(0.0, 1.0 - sum * (2.0f / uNumOfSamples));
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float A = 1.0 - sum * (2.0f * uIntensityScale / float(uNumOfSamples));
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AO = clamp(pow(A, uContrast), 0.0f, 1.0f);
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//AO = vec4(originNormal, 1.0f);
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}
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