o3de-atom-sampleviewer/Gem/Code/Lib/MaterialFunctors/StacksShaderInputFunctor.h

/*
 * 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
 *
 */

#pragma once

#include <Atom/RPI.Reflect/Material/MaterialFunctor.h>
#include <Atom/RPI.Reflect/Material/MaterialPropertyDescriptor.h>

namespace AtomSampleViewer
{
    //! This is an example of a custom hard-coded MaterialFunctor used to perform calculations on material 
    //! property values to produce shader input values.
    //! It is used by comprehensive.materialtype to transform angle values into a light direction vector.
    class StacksShaderInputFunctor final
        : public AZ::RPI::MaterialFunctor
    {
        friend class StacksShaderInputFunctorSourceData;
    public:
        AZ_RTTI(StacksShaderInputFunctor, "{7F607170-1BC2-4510-A252-8A665FC02052}", AZ::RPI::MaterialFunctor);

        static void Reflect(AZ::ReflectContext* context);
        
        using AZ::RPI::MaterialFunctor::Process;
        void Process(RuntimeContext& context) override;

    private:

        // Indices used to look up material property values at runtime
        AZ::RPI::MaterialPropertyIndex m_azimuthDegreesIndex;
        AZ::RPI::MaterialPropertyIndex m_elevationDegreesIndex;

        // Indices used to look up ShaderResourceGroup inputs at runtime
        AZ::RHI::ShaderInputConstantIndex m_lightDirectionIndex;
    };

} // namespace AtomSampleViewer