o3de-atom-sampleviewer/Shaders/OptimizationTests/DummyTransformColor.azsl

// We don't actually run this shader anywhere. It is used to test that optimization successfully strips away shader option constants.
// When the shader options are *unspecified* at build time, the pixel shader should have 9 dynamic branches in DirectX and 22 dynamic branches in Vulkan.
// When the shader options are *specificed* at build time, the pixel shader should have 0 dynamic branches on all platforms.

float3 srgb_to_linearsrgb(float3 color)
{
    return color * 2;
}


float3 linearsrgb_to_acescg(float3 color)
{
    return color * 3;
}

float3 AcesCgToAces2065(float3 color)
{
    return color * 5;
}

enum class ColorSpaceId
{
    SRGB,
    LinearSRGB,
    ACEScg,
    ACES2065,
    Invalid
};

float3 TransformColor(float3 color, ColorSpaceId fromColorSpace, ColorSpaceId toColorSpace)
{
    float3 transformedColor = color;

    static const float3 invalidColor = float3(1,0,1);

    if(fromColorSpace == ColorSpaceId::Invalid || toColorSpace == ColorSpaceId::Invalid)
    {
        transformedColor = invalidColor;
    }
    else if(fromColorSpace == toColorSpace)
    {
        return color;
    }
    else if(fromColorSpace == ColorSpaceId::SRGB && toColorSpace == ColorSpaceId::LinearSRGB)
    {
        transformedColor = srgb_to_linearsrgb(transformedColor);
    }
    else if(fromColorSpace == ColorSpaceId::LinearSRGB && toColorSpace == ColorSpaceId::ACEScg)
    {
        transformedColor = linearsrgb_to_acescg(transformedColor);
    }
    else if(fromColorSpace == ColorSpaceId::SRGB && toColorSpace == ColorSpaceId::ACEScg)
    {
        transformedColor = srgb_to_linearsrgb(transformedColor);
        transformedColor = linearsrgb_to_acescg(transformedColor);
    }
    else if(fromColorSpace == ColorSpaceId::ACEScg && toColorSpace == ColorSpaceId::ACES2065)
    {
        transformedColor = AcesCgToAces2065(transformedColor);
    }
    else
    {
        transformedColor = invalidColor;
    }
    
    return transformedColor;
}

ShaderResourceGroupSemantic SRG_Main
{
    FrequencyId = 0;
    ShaderVariantFallback = 128;
}

ShaderResourceGroup MainSrg : SRG_Main
{
    float4x4 m_modelToWorld;
    float4x4 m_viewProjectionMatrix;
    Texture2D m_texture;
    
    Sampler m_sampler
    {
        MaxAnisotropy = 16;
        AddressU = Wrap;
        AddressV = Wrap;
        AddressW = Wrap;
    };
}

option ColorSpaceId o_textureColorSpace = ColorSpaceId::Invalid;
option ColorSpaceId o_workingColorSpace = ColorSpaceId::Invalid;

struct VertexInput
{
    float3 m_position : POSITION;
    float2 m_uv : UV0;
};

struct VertexOutput
{
    float4 m_position : SV_Position;
    float2 m_uv : UV0;
};

struct PixelOutput
{
    float4 m_color : SV_Target0;
};

VertexOutput MainVS(VertexInput input)
{
    VertexOutput output;
    float4 worldPosition = mul(MainSrg::m_modelToWorld, float4(input.m_position, 1));
    output.m_position = mul(MainSrg::m_viewProjectionMatrix, worldPosition);
    output.m_uv = input.m_uv;
        
    return output;
}


PixelOutput MainPS(VertexOutput input)
{
    PixelOutput output;

    float4 sampledColor = MainSrg::m_texture.Sample(MainSrg::m_sampler, input.m_uv);
    output.m_color.xyz = TransformColor(sampledColor.xyz, o_textureColorSpace, o_workingColorSpace);
    output.m_color.a = 1.0;

    return output;
}