axmol/core/renderer/backend/Program.h

/****************************************************************************
 Copyright (c) 2018-2019 Xiamen Yaji Software Co., Ltd.

 https://axmol.dev/

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 of this software and associated documentation files (the "Software"), to deal
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 The above copyright notice and this permission notice shall be included in
 all copies or substantial portions of the Software.

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 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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 ****************************************************************************/

#pragma once

#include "Macros.h"
#include "base/Object.h"
#include "platform/PlatformMacros.h"
#include "Types.h"
#include "ShaderCache.h"

#include <functional>
#include <string>
#include <vector>
#include <unordered_map>

NS_AX_BACKEND_BEGIN

class ShaderModule;
class VertexLayout;
class ProgramManager;

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

enum class VertexLayoutType
{
    Unspec,      // needs binding after program load
    Pos,         // V2F
    Texture,     // T2F
    Sprite,      // V3F_C4B_T2F posTexColor
    DrawNode,    // V2F_C4B_T2F
    DrawNode3D,  // V3F_C4B
    SkyBox,      // V3F
    PU3D,        // V3F_C4B_T2F // same with sprite, TODO: reuse spriete
    posColor,    // V3F_C4B
    Terrain3D,   // V3F_T2F_V3F
    Count
};

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

/**
 * A program.
 */
class AX_DLL Program : public Object
{
public:
    ~Program();
    /**
     * Get engine built-in program.
     * @param type Specifies the built-in program type.
     */
    static Program* getBuiltinProgram(uint32_t type);

    /**
     * Get uniform location by name.
     * @param uniform Specifies the uniform name.
     * @return The uniform location.
     */
    virtual UniformLocation getUniformLocation(std::string_view uniform) const = 0;

    /**
     * Get uniform location by engine built-in uniform enum name.
     * @param name Specifies the engine built-in uniform enum name.
     * @return The uniform location.
     */
    virtual UniformLocation getUniformLocation(backend::Uniform name) const = 0;

    /**
     * Get attribute location by attribute name.
     * @param name Specifies the attribute name.
     * @return The attribute location.
     */
    virtual int getAttributeLocation(std::string_view name) const = 0;

    /**
     * Get attribute location by engine built-in attribute enum name.
     * @param name Specifies the engine built-in attribute enum name.
     * @return The attribute location.
     */
    virtual int getAttributeLocation(backend::Attribute name) const = 0;

    /**
     * Get maximum vertex location.
     * @return Maximum vertex locaiton.
     */
    virtual int getMaxVertexLocation() const = 0;

    /**
     * Get maximum fragment location.
     * @return Maximum fragment location.
     */
    virtual int getMaxFragmentLocation() const = 0;

    /**
     * Get active vertex attributes.
     * @return Active vertex attributes. key is active attribute name, Value is corresponding attribute info.
     */
    virtual const hlookup::string_map<AttributeBindInfo>& getActiveAttributes() const = 0;

    /**
     * Get vertex shader.
     * @return Vertex shader.
     */
    std::string_view getVertexShader() const { return _vertexShader; }

    /**
     * Get fragment shader.
     * @ Fragment shader.
     */
    std::string_view getFragmentShader() const { return _fragmentShader; }

    /**
    * Sets the program shared vertex layout type, see: VertexLayoutType
    */
    void setupVertexLayout(VertexLayoutType vlt);

    /**
     * Get engine built-in program type.
     * @return The built-in program type.
     */
    uint32_t getProgramType() const { return _programType; }

    /**
     * Get program id.
     * @return The program id.
     */
    int64_t getProgramId() const { return _programId; }

    /**
     * Get uniform buffer size in bytes that can hold all the uniforms.
     * @param stage Specifies the shader stage. The symbolic constant can be either VERTEX or FRAGMENT.
     * @return The uniform buffer size in bytes.
     */
    virtual std::size_t getUniformBufferSize(ShaderStage stage) const = 0;

    /**
     * Get all uniformInfos.
     * @return The uniformInfos.
     */
    virtual const hlookup::string_map<UniformInfo>& getAllActiveUniformInfo(ShaderStage stage) const = 0;

    inline VertexLayout* getVertexLayout() const { return _vertexLayout; }

protected:

    void setProgramIds(uint32_t progType, uint64_t progId);

    /**
     * @param vs Specifes the vertex shader source.
     * @param fs Specifes the fragment shader source.
     */
    Program(std::string_view vs, std::string_view fs);

#if AX_ENABLE_CACHE_TEXTURE_DATA
    /**
     * In case of EGL context lost, the engine will reload shaders. Thus location of uniform may changed.
     * The engine will maintain the relationship between the original uniform location and the current active uniform
     * location.
     * @param location Specifies original location.
     * @return Current active uniform location.
     * @see `int getOriginalLocation(int location) const`
     */
    virtual int getMappedLocation(int location) const = 0;

    /**
     * In case of EGL context lost, the engine will reload shaders. Thus location of uniform may changed.
     * The engine will maintain the relationship between the original uniform location and the current active uniform
     * location.
     * @param location Specifies the current active uniform location.
     * @return The original uniform location.
     * @see `int getMappedLocation(int location) const`
     */
    virtual int getOriginalLocation(int location) const = 0;

    /**
     * Get all uniform locations.
     * @return All uniform locations.
     */
    virtual const std::unordered_map<std::string, int> getAllUniformsLocation() const = 0;
    friend class ProgramState;
#endif
    friend class ProgramManager;

    std::string _vertexShader;                            ///< Vertex shader.
    std::string _fragmentShader;                          ///< Fragment shader.
    VertexLayout* _vertexLayout = nullptr;
    uint32_t _programType = ProgramType::CUSTOM_PROGRAM;  ///< built-in program type, initial value is CUSTOM_PROGRAM.
    uint64_t _programId   = 0;

    using VERTEX_LAYOUT_SETUP_FUNC = std::function<void(Program*)>;

    static std::function<void(Program*)> s_vertexLayoutSetupList[static_cast<int>(VertexLayoutType::Count)];
};

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