130 lines
4.0 KiB
Plaintext
130 lines
4.0 KiB
Plaintext
sampler_state __LUTSampler {
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Filter = Linear;
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AddressU = Clamp;
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AddressV = Clamp;
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};
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float4 generate_lut(uint bit_depth, float2 uv) {
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uint size = pow(2, bit_depth);
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uint z_size = pow(2, bit_depth / 2);
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uint container_size = pow(2, bit_depth + (bit_depth / 2));
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uint2 xy = uint2(floor(uv * container_size));
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uint2 rg = xy % size;
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uint2 bb = xy / size;
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return float4(
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rg.xy / float(size - 1),
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((bb.y * z_size) + bb.x) / float(size - 1),
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1.
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);
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};
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float4 generate_lut2(float2 uv, uint4 params0) {
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uint size = params0.r;
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uint z_size = params0.g;
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uint container_size = params0.b;
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uint2 xy = uint2(floor(uv * container_size));
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uint2 rg = xy % size;
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uint2 bb = xy / size;
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return float4(
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rg.xy / float(size - 1),
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((bb.y * z_size) + bb.x) / float(size - 1),
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1.
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);
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};
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float3 sample_lut(float3 color, uint bit_depth, texture2D lut_texture) {
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uint size = pow(2, bit_depth);
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uint z_size = pow(2, bit_depth / 2);
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uint container_size = pow(2, bit_depth + (bit_depth / 2));
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float inverse_size = 1. / size;
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float inverse_z_size = 1. / z_size;
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float inverse_container_size = 1. / container_size;
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float half_texel = inverse_container_size / 2.; // Linear sampling is weird.
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// Due to our LUT not actually being a cube but a plane pretending to be a cube,
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// we have to do some conversion into the grid structure in order to be successful.
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// 1. Clamp everything to a reasonable range.
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color = saturate(color);
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// 2. Rescale everything into 0..(size - 1)
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color *= (size - 1);
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// 3. Convert red and green into initial grid cell UVs.
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float2 xy_uv = color.xy * inverse_container_size;
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// 4. Figure out the high and low parts for interpolation.
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uint z_lo = floor(color.z);
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uint z_hi = z_lo + 1;
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// 5. Figure out the X location of the cell in the grid.
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uint z_lo_x = z_lo % z_size;
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uint z_hi_x = z_hi % z_size;
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// 6. Figure out the Y location of the cell in the grid.
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uint z_lo_y = z_lo / z_size;
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uint z_hi_y = z_hi / z_size;
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// 7. Convert the X and Y locations into UV coordinates.
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float2 z_lo_uv = float2(z_lo_x, z_lo_y) * inverse_z_size;
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float2 z_hi_uv = float2(z_hi_x, z_hi_y) * inverse_z_size;
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// 8. Sample both low and high points.
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float3 c_lo = lut_texture.Sample(__LUTSampler, xy_uv + z_lo_uv + half_texel).rgb;
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float3 c_hi = lut_texture.Sample(__LUTSampler, xy_uv + z_hi_uv + half_texel).rgb;
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// 9. Return an interpolated version based on the fraction of Z.
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return lerp(c_lo, c_hi, frac(color.z));
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};
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float3 sample_lut2(float3 color, texture2D lut_texture, int4 params0, float4 params1) {
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uint size = params0.r;
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uint z_size = params0.g;
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uint container_size = params0.b;
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float inverse_size = params1.r;
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float inverse_z_size = params1.g;
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float inverse_container_size = params1.b;
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float half_texel = params1.a;
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// Due to our LUT not actually being a cube but a plane pretending to be a cube,
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// we have to do some conversion into the grid structure in order to be successful.
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// 1. Clamp everything to a reasonable range.
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color = saturate(color);
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// 2. Rescale everything into 0..(size - 1)
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color *= (size - 1);
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// 3. Convert red and green into initial grid cell UVs.
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float2 xy_uv = color.xy * inverse_container_size;
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// 4. Figure out the high and low parts for interpolation.
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uint z_lo = floor(color.z);
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uint z_hi = z_lo + 1;
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// 5. Figure out the X location of the cell in the grid.
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uint z_lo_x = z_lo % z_size;
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uint z_hi_x = z_hi % z_size;
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// 6. Figure out the Y location of the cell in the grid.
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uint z_lo_y = z_lo / z_size;
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uint z_hi_y = z_hi / z_size;
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// 7. Convert the X and Y locations into UV coordinates.
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float2 z_lo_uv = float2(z_lo_x, z_lo_y) * inverse_z_size;
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float2 z_hi_uv = float2(z_hi_x, z_hi_y) * inverse_z_size;
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// 8. Sample both low and high points.
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float3 c_lo = lut_texture.Sample(__LUTSampler, xy_uv + z_lo_uv + half_texel).rgb;
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float3 c_hi = lut_texture.Sample(__LUTSampler, xy_uv + z_hi_uv + half_texel).rgb;
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// 9. Return an interpolated version based on the fraction of Z.
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return lerp(c_lo, c_hi, frac(color.z));
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};
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