118 lines
3.6 KiB
Plaintext
118 lines
3.6 KiB
Plaintext
// MIT License
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//
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// Copyright (c) 2024 Missing Deadlines (Benjamin Wrensch)
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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// All values used to derive this implementation are sourced from Troy�s initial AgX implementation/OCIO config file available here:
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// https://github.com/sobotka/AgX
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struct Parameters
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{
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float4 offset = float4(0.0);
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float4 slope = float4(1.0);
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float4 power = float4(1.0);
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float sat = 1.0;
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Texture2D hdrInputTexture;
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SamplerState hdrSampler;
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StructuredBuffer<float> averageLuminance;
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};
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ParameterBlock<Parameters> pToneMappingParams;
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// AgX
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// ->
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// Mean error^2: 3.6705141e-06
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float3 agxDefaultContrastApprox(float3 x) {
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float3 x2 = x * x;
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float3 x4 = x2 * x2;
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return + 15.5 * x4 * x2
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- 40.14 * x4 * x
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+ 31.96 * x4
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- 6.868 * x2 * x
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+ 0.4298 * x2
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+ 0.1191 * x
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- 0.00232;
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}
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float3 agx(float3 val) {
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const float3x3 agx_mat = transpose(float3x3(
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0.842479062253094, 0.0423282422610123, 0.0423756549057051,
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0.0784335999999992, 0.878468636469772, 0.0784336,
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0.0792237451477643, 0.0791661274605434, 0.879142973793104));
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const float min_ev = -12.47393f;
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const float max_ev = 4.026069f;
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// Input transform
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val = mul(agx_mat, val);
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// Log2 space encoding
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val = clamp(log2(val), min_ev, max_ev);
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val = (val - min_ev) / (max_ev - min_ev);
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// Apply sigmoid function approximation
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val = agxDefaultContrastApprox(val);
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return val;
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}
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float3 agxEotf(float3 val) {
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const float3x3 agx_mat_inv = transpose(float3x3(
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1.19687900512017, -0.0528968517574562, -0.0529716355144438,
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-0.0980208811401368, 1.15190312990417, -0.0980434501171241,
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-0.0990297440797205, -0.0989611768448433, 1.15107367264116));
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// Undo input transform
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val = mul(agx_mat_inv, val);
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// sRGB IEC 61966-2-1 2.2 Exponent Reference EOTF Display
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val = pow(val, float3(2.2));
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return val;
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}
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float3 agxLook(float3 val) {
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const float3 lw = float3(0.2126, 0.7152, 0.0722);
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float luma = dot(val, lw);
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// Default
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float3 offset = pToneMappingParams.offset.xyz;
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float3 slope = pToneMappingParams.slope.xyz;
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float3 power = pToneMappingParams.power.xyz;
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float sat = pToneMappingParams.sat;
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// ASC CDL
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val = pow(val * slope + offset, power);
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return luma + sat * (val - luma);
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}
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[shader("pixel")]
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float4 toneMapping(float2 uv : UV) : SV_Target
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{
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float3 hdrValue = pToneMappingParams.hdrInputTexture.Sample(pToneMappingParams.hdrSampler, uv).rgb;
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float3 value = agx(hdrValue);
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value = agxLook(value);
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value = agxEotf(value);
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return float4(hdrValue, 1);
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}
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