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o3de/Gems/Atom/Feature/Common/Assets/Shaders/Shadow/DepthExponentiation.azsl

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/*
* All or portions of this file Copyright (c) Amazon.com, Inc. or its affiliates or
* its licensors.
*
* For complete copyright and license terms please see the LICENSE at the root of this
* distribution (the "License"). All use of this software is governed by the License,
* or, if provided, by the license below or the license accompanying this file. Do not
* remove or modify any license notices. This file is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*
*/
#include <Atom/Features/Shadow/Shadow.azsli>
#include <Atom/Features/Math/Filter.azsli>
#include <Atom/Features/Shadow/ShadowmapAtlasLib.azsli>
#include <Atom/Features/SrgSemantics.azsli>
#include <Atom/RPI/Math.azsli>
static const uint MaxCascadeCount = 4;
option enum class ShadowmapLightType
{
Directional,
Spot
}
o_shadowmapLightType = ShadowmapLightType::Directional;
ShaderResourceGroup PassSrg : SRG_PerPass_WithFallback
{
Texture2DArray<float> m_inputShadowmap;
RWTexture2DArray<float> m_outputShadowmap;
Buffer<uint2> m_shadowmapIndexTable;
StructuredBuffer<FilterParameter> m_filterParameters;
}
[numthreads(8,8,1)]
void MainCS(uint3 dispatchId: SV_DispatchThreadID)
{
const float3 inputSize = GetImageSize(PassSrg::m_inputShadowmap);
const float3 outputSize = GetImageSize(PassSrg::m_outputShadowmap);
const float depthInClip = PassSrg::m_inputShadowmap[dispatchId].r;
const uint shadowmapIndex = GetShadowmapIndex(
PassSrg::m_shadowmapIndexTable,
dispatchId,
inputSize.x);
if (shadowmapIndex == ~0)
{
return; // Early return if it is outside of shadowmaps.
}
const FilterParameter filterParameter = PassSrg::m_filterParameters[shadowmapIndex];
if (!filterParameter.m_isEnabled)
{
return; // Early return if filter is disabled.
}
switch (o_shadowmapLightType)
{
case ShadowmapLightType::Directional:
{
const float distanceMin = filterParameter.m_lightDistanceOfCameraViewFrustum;
// When the light origin is far from the camera view frustum,
// the difference of "depthInClip" in the frustum is so small,
// and it often causes light bleeding with ESM.
// So this converts it to "depth" to emphasize the difference
// within the frustum.
const float depth = (depthInClip - distanceMin) / (1. - distanceMin);
// Todo: Expose Esm exponent slider for directional lights
// This would remove the exp calculation below, collapsing it into a subtraction in DirectionalLightShadow.azsli
// ATOM-15775
const float outValue = exp(EsmExponentialShift * depth);
PassSrg::m_outputShadowmap[dispatchId].r = outValue;
break;
}
case ShadowmapLightType::Spot:
{
const float3 coefficients = float3(
filterParameter.m_n_f_n,
filterParameter.m_n_f,
filterParameter.m_f);
// With a spot light shadowmap, "depthInClip" is calculated
// as a perspective depth, not a orthogonal one.
// So the values are concentrated to near 1.0,
// and it often causes light bleeding with ESM.
// So this converts it to a linear depth to emphasize the
// difference like a orthogonal depth.
PassSrg::m_outputShadowmap[dispatchId].r = PerspectiveDepthToLinear(depthInClip, coefficients);
break;
}
}
}