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o3de/Gems/Atom/Feature/Common/Assets/Shaders/DiffuseGlobalIllumination/DiffuseProbeGridDownsample....

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/*
* Copyright (c) Contributors to the Open 3D Engine Project.
* For complete copyright and license terms please see the LICENSE at the root of this distribution.
*
* SPDX-License-Identifier: Apache-2.0 OR MIT
*
*/
#include <scenesrg.srgi>
#include <viewsrg.srgi>
#include <Atom/Features/PostProcessing/FullscreenVertexUtil.azsli>
#include <Atom/Features/PostProcessing/FullscreenVertexInfo.azsli>
#include <Atom/RPI/Math.azsli>
ShaderResourceGroup PassSrg : SRG_PerPass
{
Texture2DMS<float4> m_normal; // RGB10 = Normal (Encoded), A2 = Flags
Texture2DMS<float> m_depth;
Sampler LinearSampler
{
MinFilter = Linear;
MagFilter = Linear;
MipFilter = Linear;
AddressU = Clamp;
AddressV = Clamp;
AddressW = Clamp;
};
// scale multiplier of the downsampled size to the fullscreen size (e.g., 4)
uint m_outputImageScale;
}
#include <Atom/RPI/ShaderResourceGroups/DefaultDrawSrg.azsli>
// Vertex Shader
VSOutput MainVS(VSInput input)
{
VSOutput OUT;
float4 posTex = GetVertexPositionAndTexCoords(input.m_vertexID);
OUT.m_texCoord = float2(posTex.z, posTex.w);
OUT.m_position = float4(posTex.x, posTex.y, 0.0, 1.0);
return OUT;
}
struct PSOutput
{
float m_depth : SV_Depth;
float4 m_normal : SV_Target0;
};
// Pixel Shader
PSOutput MainPS(VSOutput IN, in uint sampleIndex : SV_SampleIndex)
{
uint2 screenCoords = IN.m_position.xy * PassSrg::m_outputImageScale;
float downsampledDepth = 0;
float4 downsampledEncodedNormal;
for (uint y = 0; y < PassSrg::m_outputImageScale; ++y)
{
for (uint x = 0; x < PassSrg::m_outputImageScale; ++x)
{
float depth = PassSrg::m_depth.Load(screenCoords + int2(x, y), sampleIndex).r;
float4 encodedNormal = PassSrg::m_normal.Load(screenCoords + int2(x, y), sampleIndex);
// take the closest depth sample to ensure we're getting the normal closest to the viewer
// (larger depth value due to reverse depth)
if (depth > downsampledDepth)
{
downsampledDepth = depth;
downsampledEncodedNormal = encodedNormal;
}
}
}
float3 downsampledNormal = DecodeNormalSignedOctahedron(downsampledEncodedNormal.rgb);
PSOutput OUT;
OUT.m_depth = downsampledDepth;
OUT.m_normal = float4(downsampledNormal * 0.5f + 0.5f, 0.0f);
return OUT;
}