o3de/Gems/DiffuseProbeGrid/Assets/Shaders/DiffuseGlobalIllumination/DiffuseProbeGridVisualizationComposite.azsl

/*
 * 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/Features/PostProcessing/FullscreenPixelInfo.azsli>
#include <Atom/Features/PBR/LightingUtils.azsli>
#include <Atom/RPI/Math.azsli>

ShaderResourceGroup PassSrg : SRG_PerPass
{
    Texture2D<float4> m_visualization;
    Texture2D<float>  m_depth;
    
    Sampler LinearSampler
    {
        MinFilter = Linear;
        MagFilter = Linear;
        MipFilter = Linear;
        AddressU = Clamp;
        AddressV = Clamp;
        AddressW = Clamp;
    };
}

// Vertex Shader
VSOutput MainVS(VSInput input)
{
    VSOutput OUT;

    float4 posTex = GetVertexPositionAndTexCoords(input.m_vertexID);
    OUT.m_position = float4(posTex.x, posTex.y, 0.0, 1.0);

    return OUT;
}

// Pixel Shader
PSOutput MainPS(VSOutput IN)
{
    uint2 screenCoords = IN.m_position.xy;
    float depth = PassSrg::m_depth.Load(uint3(screenCoords, 0)).r;
    float4 visualization = PassSrg::m_visualization.Load(uint3(screenCoords, 0));

    if (!any(visualization))
    {
        discard;
    }

    if (depth > visualization.a)
    {
        discard;
    }

    PSOutput OUT;
    OUT.m_color = float4(visualization.rgb, 1.0f);
    return OUT;
}