/*
* 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 <viewsrg.srgi>

#include <Atom/Features/PostProcessing/FullscreenVertex.azsli>

ShaderResourceGroup PassSrg : SRG_PerPass
{
    // D32_FLOAT_S8X24_UINT (Format:15) depthStencil texture
    Texture2D<float2> m_depthStencil;
    Sampler LinearSampler
    {
        MinFilter = Linear;
        MagFilter = Linear;
        MipFilter = Linear;
        AddressU = Clamp;
        AddressV = Clamp;
        AddressW = Clamp;
    };
}

struct PSOutput
{
    float m_linearDepth : SV_Target0;
};

PSOutput MainPS(VSOutput IN)
{
    PSOutput OUT;

    float zDepth = PassSrg::m_depthStencil.Sample(PassSrg::LinearSampler, IN.m_texCoord).r;
    float linearDepth = 
        abs(((ViewSrg::GetFarZTimesNearZ()) / (ViewSrg::GetFarZMinusNearZ() * zDepth - ViewSrg::GetFarZ()))); 

    OUT.m_linearDepth = linearDepth;
    return OUT;
}