axmol/core/renderer/backend/Program.h

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

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#pragma once

#include "Macros.h"
#include "base/CCRef.h"
#include "platform/CCPlatformMacros.h"
#include "Types.h"
#include "ShaderCache.h"

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

CC_BACKEND_BEGIN

class ShaderModule;

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

/**
 * A program.
 */
class CC_DLL Program : public Ref
{
public:
    /**
     * 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; }

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

    /**
     * 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 a uniformInfo in given location from the specific shader stage.
     * @param stage Specifies the shader stage. The symbolic constant can be either VERTEX or FRAGMENT.
     * @param location Specifies the uniform locaion.
     * @return The uniformInfo.
     */
    virtual const UniformInfo& getActiveUniformInfo(ShaderStage stage, int location) const = 0;

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

    /**
     * Set engin built-in program type.
     * @param type Specifies the program type.
     */
    void setProgramType(uint32_t type);

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

#if CC_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 ProgramCache;

    std::string _vertexShader;                            ///< Vertex shader.
    std::string _fragmentShader;                          ///< Fragment shader.
    uint32_t _programType = ProgramType::CUSTOM_PROGRAM;  ///< built-in program type, initial value is CUSTOM_PROGRAM.
};

// end of _backend group
/// @}
CC_BACKEND_END