o3de-azslc/tests/Emission/specialization-constants-vk.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
 *
 */
 
/*
 * Demonstrates the use of shader variants (options)
 *
 * Global constants and SRG constants marked with the "option" qualifier are treated as variant options
 */
 
enum class QualityT {Low, Medium, High};
// Option keyword   Type     Name      Default value (hint)
option              QualityT Quality = QualityT::High;

// Boolean is supported
option bool UseGI = true;

// Integer is supported
[range(1, 64)]
option int IntOption         = 42;

ShaderResourceGroupSemantic ExampleBinding 
{
    FrequencyId = 0; 
    ShaderVariantFallback = 64;
};

ShaderResourceGroup ExampleSRG : ExampleBinding
{
    float4 exampleColor;
};

struct VertexInput  { float3 m_position : POSITION; };

struct VertexOutput { float4 m_position : SV_Position; };

VertexOutput MainVS(VertexInput input)
{
    VertexOutput output;
    output.m_position = float4(input.m_position, 1.0);
    return output;
}

float4 MainPS() : SV_Target0
{
    switch (Quality)
    {
        case QualityT::Low:     return ExampleSRG::exampleColor * float4(IntOption, 0, 0, 0);
        case QualityT::Medium:  return ExampleSRG::exampleColor * float4(0, IntOption, 0, 0);
        case QualityT::High:    return ExampleSRG::exampleColor * float4(0, 0, IntOption, 0);
        default:                return ExampleSRG::exampleColor; // https://github.com/microsoft/DirectXShaderCompiler/issues/2331
    }
}