116 lines
4.1 KiB
GLSL
116 lines
4.1 KiB
GLSL
// From http://graphics.cs.aueb.gr/graphics/research_illumination.html
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// "Real-Time Diffuse Global Illumination Using Radiance Hints"
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// paper and shader code
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uniform float R_wcs = 10.; // Rmax: maximum sampling distance (in WCS units)
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uniform vec3 extents;
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uniform mat4 RHMatrix;
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uniform mat4 RSMMatrix;
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uniform sampler2D dtex;
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uniform sampler2D ctex;
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uniform sampler2D ntex;
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flat in int slice;
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layout (location = 0) out vec4 SHRed;
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layout (location = 1) out vec4 SHGreen;
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layout (location = 2) out vec4 SHBlue;
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vec3 resolution = vec3(32, 16, 32);
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#define SAMPLES 16
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vec4 SHBasis (const in vec3 dir)
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{
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float L00 = 0.282095;
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float L1_1 = 0.488603 * dir.y;
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float L10 = 0.488603 * dir.z;
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float L11 = 0.488603 * dir.x;
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return vec4 (L11, L1_1, L10, L00);
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}
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vec4 DirToSh(vec3 dir, float flux)
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{
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return SHBasis (dir) * flux;
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}
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// We need to manually unroll the loop, otherwise Nvidia driver crashes.
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void loop(in int i,
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in vec3 RHcenter,in vec3 RHCellSize, in vec2 RHuv, in float RHdepth,
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inout vec4 SHr, inout vec4 SHg, inout vec4 SHb)
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{
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// produce a new sample location on the RSM texture
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float alpha = (i + .5) / SAMPLES;
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float theta = 2. * 3.14 * 7. * alpha;
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float h = alpha;
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vec2 offset = h * vec2(cos(theta), sin(theta));
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vec2 uv = RHuv + offset * 0.01;
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// Get world position and normal from the RSM sample
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float depth = texture(dtex, uv).x;
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vec4 RSMPos = inverse(RSMMatrix) * (2. * vec4(uv, depth, 1.) - 1.);
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RSMPos /= RSMPos.w;
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vec3 RSMAlbedo = texture(ctex, uv).xyz;
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vec3 normal = normalize(2. * texture(ntex, uv).xyz - 1.);
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// Sampled location inside the RH cell
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vec3 offset3d = vec3(uv, 0);
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vec3 SamplePos = RHcenter + .5 * offset3d.xzy * RHCellSize;
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// Normalize distance to RSM sample
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float dist = distance(SamplePos, RSMPos.xyz) / R_wcs;
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// Determine the incident direction.
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// Avoid very close samples (and numerical instability problems)
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vec3 RSM_to_RH_dir = (dist <= 0.1) ? vec3(0.) : normalize(SamplePos - RSMPos.xyz);
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float dotprod = max(dot(RSM_to_RH_dir, normal.xyz), 0.);
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float factor = dotprod / (0.1 + dist * dist);
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vec3 color = RSMAlbedo.rgb * factor;
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SHr += DirToSh(RSM_to_RH_dir, color.r);
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SHg += DirToSh(RSM_to_RH_dir, color.g);
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SHb += DirToSh(RSM_to_RH_dir, color.b);
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}
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void main(void)
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{
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vec3 normalizedRHCenter = 2. * vec3(gl_FragCoord.xy, slice) / resolution - 1.;
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vec3 RHcenter = (RHMatrix * vec4(normalizedRHCenter * extents, 1.)).xyz;
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vec4 ShadowProjectedRH = RSMMatrix * vec4(RHcenter, 1.);
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vec3 RHCellSize = extents / resolution;
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vec2 RHuv = .5 * ShadowProjectedRH.xy / ShadowProjectedRH.w + .5;
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float RHdepth = .5 * ShadowProjectedRH.z / ShadowProjectedRH.w + .5;
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vec4 SHr = vec4(0.);
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vec4 SHg = vec4(0.);
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vec4 SHb = vec4(0.);
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int x = int(gl_FragCoord.x), y = int(gl_FragCoord.y);
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float phi = 30. * (x ^ y) + 10. * x * y;
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loop(0, RHcenter, RHCellSize, RHuv, RHdepth, SHr, SHg, SHb);
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loop(1, RHcenter, RHCellSize, RHuv, RHdepth, SHr, SHg, SHb);
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loop(2, RHcenter, RHCellSize, RHuv, RHdepth, SHr, SHg, SHb);
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loop(3, RHcenter, RHCellSize, RHuv, RHdepth, SHr, SHg, SHb);
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loop(4, RHcenter, RHCellSize, RHuv, RHdepth, SHr, SHg, SHb);
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loop(5, RHcenter, RHCellSize, RHuv, RHdepth, SHr, SHg, SHb);
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loop(6, RHcenter, RHCellSize, RHuv, RHdepth, SHr, SHg, SHb);
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loop(7, RHcenter, RHCellSize, RHuv, RHdepth, SHr, SHg, SHb);
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loop(8, RHcenter, RHCellSize, RHuv, RHdepth, SHr, SHg, SHb);
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loop(9, RHcenter, RHCellSize, RHuv, RHdepth, SHr, SHg, SHb);
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loop(10, RHcenter, RHCellSize, RHuv, RHdepth, SHr, SHg, SHb);
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loop(11, RHcenter, RHCellSize, RHuv, RHdepth, SHr, SHg, SHb);
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loop(12, RHcenter, RHCellSize, RHuv, RHdepth, SHr, SHg, SHb);
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loop(13, RHcenter, RHCellSize, RHuv, RHdepth, SHr, SHg, SHb);
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loop(14, RHcenter, RHCellSize, RHuv, RHdepth, SHr, SHg, SHb);
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loop(15, RHcenter, RHCellSize, RHuv, RHdepth, SHr, SHg, SHb);
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SHr /= 3.14159 * SAMPLES;
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SHg /= 3.14159 * SAMPLES;
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SHb /= 3.14159 * SAMPLES;
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SHRed = SHr;
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SHGreen = SHg;
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SHBlue = SHb;
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}
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