o3de-atom-sampleviewer/Shaders/RHI/Triangle.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 <Atom/Features/SrgSemantics.azsli>

ShaderResourceGroup TriangleInstanceSrg : SRG_PerDraw
{
    column_major float4x4 m_objectMatrix;
}

struct VSInput
{
    float3 m_position : POSITION;
    float4 m_color : COLOR0;
};

struct VSOutput
{
    float4 m_position : SV_Position;
    float4 m_color : COLOR0;
};

// Red: normal draw mode (rgb = rgb). The Red corner appears on top
// Green: shift the colors so Green is on top (the top vertex is (1, 0, 0) so the green color should come from .r
// Blue: shift the colors so Blue is on top (the top vertex is (1, 0, 0) so the blue color should come from .r
// White: ignore original colors and draw everything white
option enum class DrawMode { Red, Green, Blue, White} o_drawMode;

VSOutput MainVS(VSInput vsInput)
{
    VSOutput OUT;
    OUT.m_position = mul(float4(vsInput.m_position, 1.0), TriangleInstanceSrg::m_objectMatrix);
    OUT.m_color = vsInput.m_color;
    return OUT;
}

struct PSOutput
{
    float4 m_color : SV_Target0;
};

PSOutput MainPS(VSOutput vsOutput)
{
    PSOutput OUT;
    
    switch (o_drawMode)
    {
        case DrawMode::Red:
            OUT.m_color = vsOutput.m_color.rgba;
            break;

        case DrawMode::Green:
            OUT.m_color = vsOutput.m_color.brga;
            break;

        case DrawMode::Blue:
            OUT.m_color = vsOutput.m_color.gbra;
            break;

        case DrawMode::White:
            OUT.m_color = float4(1, 1, 1, vsOutput.m_color.a);
            break;
    }

    // Simple tonemapping:
    OUT.m_color.rgb = pow(OUT.m_color.rgb, 1.0/2.2);
    return OUT;
}