ShaderTechnique.h

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/* Copyright (C) 2024 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * 0 A.D. is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef INCLUDED_SHADERTECHNIQUE
#define INCLUDED_SHADERTECHNIQUE
 
#include "graphics/ShaderDefines.h"
#include "graphics/ShaderProgram.h"
#include "graphics/ShaderTechniquePtr.h"
#include "lib/code_annotation.h"
#include "lib/file/vfs/vfs_path.h"
#include "renderer/backend/PipelineState.h"
 
#include <functional>
#include <memory>
#include <vector>
 
/**
 * Implements a render pass consisting of a pipeline state and a shader,
 * used by CShaderTechnique.
 */
class CShaderPass
{
public:
    CShaderPass(
        std::unique_ptr<Renderer::Backend::IGraphicsPipelineState> pipelineState,
        const CShaderProgramPtr& shader);
    MOVABLE(CShaderPass);
 
    const CShaderProgramPtr& GetShaderProgram() const noexcept { return m_Shader; }
 
    Renderer::Backend::IGraphicsPipelineState*
    GetPipelineState() const noexcept { return m_PipelineState.get(); }
 
private:
    CShaderProgramPtr m_Shader;
 
    std::unique_ptr<Renderer::Backend::IGraphicsPipelineState> m_PipelineState;
};
 
/**
 * Implements a render technique consisting of a sequence of passes.
 * CShaderManager loads these from shader effect XML files.
 */
class CShaderTechnique
{
public:
    using PipelineStateDescCallback =
        std::function<void(Renderer::Backend::SGraphicsPipelineStateDesc& pipelineStateDesc)>;
 
    CShaderTechnique(const VfsPath& path, const CShaderDefines& defines, const PipelineStateDescCallback& callback);
 
    void SetPasses(std::vector<CShaderPass>&& passes);
    void SetComputePipelineState(
        std::unique_ptr<Renderer::Backend::IComputePipelineState> pipelineState,
        const CShaderProgramPtr& computeShader);
 
    int GetNumPasses() const;
 
    Renderer::Backend::IShaderProgram* GetShader(int pass = 0) const;
 
    Renderer::Backend::IGraphicsPipelineState*
    GetGraphicsPipelineState(int pass = 0) const;
 
    Renderer::Backend::IComputePipelineState*
    GetComputePipelineState() const;
 
    /**
     * Whether this technique uses alpha blending that requires objects to be
     * drawn from furthest to nearest.
     */
    bool GetSortByDistance() const;
 
    void SetSortByDistance(bool enable);
 
    const VfsPath& GetPath() { return m_Path; }
 
    const CShaderDefines& GetShaderDefines() { return m_Defines; }
 
    const PipelineStateDescCallback& GetPipelineStateDescCallback() const { return m_PipelineStateDescCallback; };
 
private:
    std::vector<CShaderPass> m_Passes;
 
    bool m_SortByDistance = false;
 
    // We need additional data to reload the technique.
    VfsPath m_Path;
    CShaderDefines m_Defines;
 
    PipelineStateDescCallback m_PipelineStateDescCallback;
 
    std::unique_ptr<Renderer::Backend::IComputePipelineState> m_ComputePipelineState;
    CShaderProgramPtr m_ComputeShader;
};
 
#endif // INCLUDED_SHADERTECHNIQUE