axmol/core/renderer/backend/ProgramManager.h

/****************************************************************************
 Copyright (c) 2018-2019 Xiamen Yaji Software Co., Ltd.
 Copyright (c) 2019-present Axmol Engine contributors (see AUTHORS.md).

 https://axmol.dev/

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#pragma once

#include "Macros.h"
#include "base/Object.h"
#include "platform/PlatformMacros.h"
#include "Program.h"

#include <string>
#include <unordered_map>
#include <string_view>
#include "ProgramStateRegistry.h"

struct XXH64_state_s;

NS_AX_BACKEND_BEGIN
/**
 * @addtogroup _backend
 * @{
 */

/**
 * Cache and reuse program object.
 */
class AX_DLL ProgramManager
{
public:
    /** returns the shared instance */
    static ProgramManager* getInstance();

    /** purges the cache. It releases the retained instance. */
    static void destroyInstance();

    /// get built-in program
    Program* getBuiltinProgram(uint32_t type);

    /**
     * register a custom program
     * @return
     *   the id of custom program, 0: fail, the id can use by loadProgram
     */
    uint64_t registerCustomProgram(std::string_view vsName,
                                   std::string_view fsName,
                                   VertexLayoutType vlt = VertexLayoutType::Unspec,
                                   bool force           = false);

    /**
     * load a builtin/or custom program:
     * @param id: the id of program to load, the id value returned by registerCustomProgram
     *            or builtin programType, whe the id < ProgramType:BUILTIN_COUNT, this function
     *            is identical to 'getBuiltinProgram'
     */
    Program* loadProgram(uint64_t progId);

    /**
    * @brief Load a program with vsName, fsName as CUSTOM immediately without register
    * @param vsName the vertex shader name: custom/xxx_vs
    * @param fsName the fragment shader name: custom/xxx_vs
    * @param vlt the builtin vertex layout type used for loading program
    * @return Program* (nullable)
    * @remark the returend program type always ProgramType::CUSTOM_PROGRAM
    */
    Program* loadProgram(std::string_view vsName,
                               std::string_view fsName,
                               VertexLayoutType vlt = VertexLayoutType::Unspec);

     /**
     * Unload a program object from cache.
     * @param program Specifies the program object to move.
     */
    void unloadProgram(Program* program);

    /**
     * Unload all unused program objects from cache.
     */
    void unloadUnusedPrograms();

    /**
     * Unload all program objects from cache.
     */
    void unloadAllPrograms();

    /**
     * Remove a program object from cache.
     * @param program Specifies the program object to move.
     */
    AX_DEPRECATED_ATTRIBUTE void removeProgram(Program* prog) { unloadProgram(prog); }

    /**
     * Remove all unused program objects from cache.
     */
    AX_DEPRECATED_ATTRIBUTE void removeUnusedProgram() { unloadUnusedPrograms(); }

    /**
     * Remove all program objects from cache.
     */
    AX_DEPRECATED_ATTRIBUTE void removeAllPrograms() { unloadAllPrograms(); }

protected:
    ProgramManager();
    virtual ~ProgramManager();

    /**
     * Pre-load programs into cache.
     */
    bool init();

    /**
     * register a program
     */
    uint64_t registerProgram(uint32_t progType,
                             std::string_view vsName,
                             std::string_view fsName,
                             VertexLayoutType vlt,
                             bool force = false);

    /**
     * load a custom program by vsName, fsName, vertexLayout
     */
    Program* loadProgram(std::string_view vsName,
                         std::string_view fsName,
                         uint32_t progType,
                         uint64_t progId,
                         VertexLayoutType vlt);

    uint64_t computeProgramId(std::string_view vsName, std::string_view fsName);

    struct BuiltinRegInfo
    {  // builtin shader name is literal string, so use std::string_view ok
        std::string_view vsName;
        std::string_view fsName;
        VertexLayoutType vlt;
    };

    BuiltinRegInfo _builtinRegistry[(int)backend::ProgramType::BUILTIN_COUNT];
    std::unordered_map<int64_t, BuiltinRegInfo> _customRegistry;

    std::unordered_map<int64_t, Program*> _cachedPrograms;  ///< The cached program object.

    XXH64_state_s* _programIdGen;

    static ProgramManager* _sharedProgramManager;  ///< A shared instance of the program cache.
};

using ProgramCache = ProgramManager;  // for compatible

// end of _backend group
/// @}
NS_AX_BACKEND_END

/**
 * @alias some feq use types to namespace ax
 */

NS_AX_BEGIN

using ProgramType      = ::ax::backend::ProgramType;
using ProgramState     = ::ax::backend::ProgramState;
using Program          = ::ax::backend::Program;
using VertexLayout     = ::ax::backend::VertexLayout;
using VertexLayoutType = ::ax::backend::VertexLayoutType;
using ProgramManager   = ::ax::backend::ProgramManager;
using ProgramRegistry  = ::ax::backend::ProgramStateRegistry;

NS_AX_END