OpenGL Program渲染框架

Program.h

#pragma once
#ifndef Program_h
#define Program_h

class Program
{
public:
    /// Constructor for a rendering program
    Program(
        const std::vector<const char*>& vertexShaderCode,
        const std::vector<const char*>& fragmentShaderCode);
    /// Constructor for a rendering program
    Program(
        const std::vector<const char*>& vertexShaderCode,
        const std::vector<const char*>& geometryShaderCode,
        const std::vector<const char*>& fragmentShaderCode);
    /// Constructor for a tessellation program
    Program(
        const std::vector<const char*>& vertexShaderCode,
        const std::vector<const char*>& controlShaderCode,
        const std::vector<const char*>& evaluationShaderCode,
        const std::vector<const char*>& geometryShaderCode,
        const std::vector<const char*>& fragmentShaderCode);
    /// Constructor for a compute program
    Program(const std::vector<const char*>& computeShaderCode);
    /// Destructor
    ~Program();

    /// Binds this shader program
    void bind();
    /// Unbinds this shader program
    void unbind();
    /// Returns the location of the attribute with the provided name in the shader
    GLint getAttributeLocation(const std::string& name) const;
    /// Returns the location to the uniform with the provided name in the shader
    GLint getUniformLocation(const std::string& name) const;
    /// Returns the index to the interface block with the provided name in the shader
    GLint getInterfaceBlockIndex(const std::string& name) const;
    /// Binds the shader storage buffer to the interface block index with the provided name
    void setSSBO(const std::string& name, GLuint bufferHandle);
    /// Sets the uniform to the provided value
    void setUniformBool(const std::string& name, bool x);
    /// Sets the uniform to the provided value
    void setUniform1f(const std::string& name, float x);
    /// Sets the uniform to the provided value
    void setUniform1i(const std::string& name, int x);
    /// Sets the uniform to the provided value
    void setUniform2f(const std::string& name, const Eigen::Vector2f& x);
    /// Sets the uniform to the provided value
    void setUniform2fArray(const std::string& name, const std::vector<Eigen::Vector2f>& x);
    /// Sets the uniform to the provided value
    void setUniform2i(const std::string& name, const Eigen::Vector2i& x);
    /// Sets the uniform to the provided value
    void setUniform4f(const std::string& name, const Eigen::Vector4f& x);
    /// Sets the uniform to the provided value
    void setMatrix4f(const std::string& name, const Eigen::Matrix4f& m);
    /// Sets all camera uniforms
    void setCamera(const Camera& camera);
    /// Assigns threads to workgroups and executes the compute shader
    void compute1D(int numThreads);

private:
    /// Concatenates the individual shader pieces to one string
    std::string makeString(const std::vector<const char*> shaderCode);
    /// Creates and compiles a shader object from the provided source code
    GLuint createShader(GLenum shaderType, const char* shaderCode) const;
    /// Links the given shaders into the shader program
    void link();
    /// Acquires and updates data about the linked program using the introspection API
    void getIntrospectionData();
    /// Retrieves the block binding index for the provided interface block
    GLuint getBlockBinding(GLuint interfaceBlockIndex);

public:
    GLuint mHandle = 0u;    ///< OpenGL handle of the linked program

    GLuint mVertexShaderHandle = 0u;        ///< OpenGL handle of the compiled vertex shader, if present
    GLuint mControlShaderHandle = 0u;        ///< OpenGL handle of the compiled tessellation control shader, if present
    GLuint mEvaluationShaderHandle = 0u;    ///< OpenGL handle of the compiled tessellation evaluation shader, if present
    GLuint mGeometryShaderHandle = 0u;        ///< OpenGL handle of the compiled geometry shader, if present
    GLuint mFragmentShaderHandle = 0u;        ///< OpenGL handle of the compiled fragment shader, if present
    GLuint mComputeShaderHandle = 0u;        ///< OpenGL handle of the compiled compute shader, if present

    GLuint mBlockBindingCounter = 0u;    ///< Counter to provide interface block binding indices

    std::unordered_map<GLuint, GLuint> mBlockBindings;
    std::unordered_map<std::string, IntrospectionInput> mInputs;
    std::unordered_map<std::string, IntrospectionInterfaceBlock> mInterfaceBlocks;
    std::unordered_map<std::string, IntrospectionUniform> mUniforms;
};

#endif

可以看到Program类一共有4个构造函数，初始化参数有：vertexShaderCode和fragmentShaderCode（构造函数1），vertexShaderCode、geometryShaderCode和fragmentShaderCode（构造函数2），vertexShaderCode、controlShaderCode、evaluationShaderCode、geometryShaderCode和fragmentShaderCode（构造函数3），computeShaderCode（构造函数4）。

Program类的实现：

//=================================================================================================
/**
*    Constructor for a rendering program.
*
*    @author    Daniel Cornel
**/
//=================================================================================================
Program::Program(
    const std::vector<const char*>& vertexShaderCode,
    const std::vector<const char*>& fragmentShaderCode)
{
    mVertexShaderHandle = createShader(GL_VERTEX_SHADER, makeString(vertexShaderCode).c_str());
    mFragmentShaderHandle = createShader(GL_FRAGMENT_SHADER, makeString(fragmentShaderCode).c_str());

    mHandle = glCreateProgram();

    glAttachShader(mHandle, mVertexShaderHandle);
    glAttachShader(mHandle, mFragmentShaderHandle);

    glBindFragDataLocation(mHandle, 0, "outColor");

    link();
}
//=================================================================================================
/**
*    Constructor for a rendering program.
*
*    @author    Daniel Cornel
**/
//=================================================================================================
Program::Program(
    const std::vector<const char*>& vertexShaderCode,
    const std::vector<const char*>& geometryShaderCode,
    const std::vector<const char*>& fragmentShaderCode)
{
    mVertexShaderHandle = createShader(GL_VERTEX_SHADER, makeString(vertexShaderCode).c_str());
    mGeometryShaderHandle = createShader(GL_GEOMETRY_SHADER, makeString(geometryShaderCode).c_str());
    mFragmentShaderHandle = createShader(GL_FRAGMENT_SHADER, makeString(fragmentShaderCode).c_str());

    mHandle = glCreateProgram();

    glAttachShader(mHandle, mVertexShaderHandle);
    glAttachShader(mHandle, mGeometryShaderHandle);
    glAttachShader(mHandle, mFragmentShaderHandle);

    glBindFragDataLocation(mHandle, 0, "outColor");

    link();
}
//=================================================================================================
/**
*    Constructor for a tessellation program.
*
*    @author    Daniel Cornel
**/
//=================================================================================================
Program::Program(
    const std::vector<const char*>& vertexShaderCode,
    const std::vector<const char*>& controlShaderCode,
    const std::vector<const char*>& evaluationShaderCode,
    const std::vector<const char*>& geometryShaderCode,
    const std::vector<const char*>& fragmentShaderCode)
{
    mVertexShaderHandle = createShader(GL_VERTEX_SHADER, makeString(vertexShaderCode).c_str());
    mControlShaderHandle = createShader(GL_TESS_CONTROL_SHADER, makeString(controlShaderCode).c_str());
    mEvaluationShaderHandle = createShader(GL_TESS_EVALUATION_SHADER, makeString(evaluationShaderCode).c_str());
    mGeometryShaderHandle = createShader(GL_GEOMETRY_SHADER, makeString(geometryShaderCode).c_str());
    mFragmentShaderHandle = createShader(GL_FRAGMENT_SHADER, makeString(fragmentShaderCode).c_str());

    mHandle = glCreateProgram();

    glAttachShader(mHandle, mVertexShaderHandle);
    glAttachShader(mHandle, mControlShaderHandle);
    glAttachShader(mHandle, mEvaluationShaderHandle);
    glAttachShader(mHandle, mGeometryShaderHandle);
    glAttachShader(mHandle, mFragmentShaderHandle);

    glBindFragDataLocation(mHandle, 0, "outColor");

    link();
}
//=================================================================================================
/**
*    Constructor for a compute program.
*
*    @author    Daniel Cornel
**/
//=================================================================================================
Program::Program(const std::vector<const char*>& computeShaderCode)
{
    mComputeShaderHandle = createShader(GL_COMPUTE_SHADER, makeString(computeShaderCode).c_str());

    mHandle = glCreateProgram();

    glAttachShader(mHandle, mComputeShaderHandle);

    link();
}

参考：Daniel Cornel, Watertight Incremental Heightfield Tessellation,http://drivenbynostalgia.com/