OpenGL自制3D游戏引擎入门VI

Shader II 创建自己的着色器类

一、从文件读取

1. 我们从C++文件流读取着色器内容，存储到几个String对象中
   

Shader.h代码如下

    #pragma once
    #include <string>

    using namespace std;
    class Shader
    {
    public:
        Shader(const char* vertexPath, const char* fragmentPath);
        //~Shader();
        string vertexString;
        string fragmentString;
        const char* vertexSource;
        const char* fragmentSource;
    };

Shader.cpp代码如下

    #include <iostream>
    #include <fstream>
    #include <sstream>

    #include "Shader.h"

    using namespace std;

    Shader::Shader(const char* vertexPath, const char* fragmentPath)
    {
        ifstream vertexFile;
        ifstream fragmentFile;

        stringstream vertexSStream;
        stringstream frangmentSStream;

        vertexFile.open(vertexPath);
        fragmentFile.open(fragmentPath);
        vertexFile.exceptions(ifstream::failbit || ifstream::badbit);
        fragmentFile.exceptions(ifstream::failbit || ifstream::badbit);

        try
        {
            if (!vertexFile.is_open() || !fragmentFile.is_open())
            {
                throw exception("open File error");
            }

            vertexSStream << vertexFile.rdbuf();
            frangmentSStream << fragmentFile.rdbuf();

            vertexString = vertexSStream.str();
            fragmentString = frangmentSStream.str();

            vertexSource = vertexString.c_str();
            fragmentSource = fragmentString.c_str();

            printf(vertexSource);
            printf("\n");
            printf(fragmentSource);

        }
        catch (const exception& e)
        {
            printf(e.what());
        }
    }

main函数中声明着色器类并修改对应文件

    Shader* testShader = new Shader("vertexSource.txt", "fragmentSource.txt");

    unsigned int vertexShader;
    vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &testShader->vertexSource, NULL);
    glCompileShader(vertexShader);

    unsigned int fragmentShader;
    fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &testShader->fragmentSource, NULL);
    glCompileShader(fragmentShader);

二、编译和链接着色器

1. Shader.cpp

    #include <iostream>
    #include <fstream>
    #include <sstream>
   
    #include <GL/glew.h>
    #include <GLFW/glfw3.h>
   
    #include "Shader.h"
   
    using namespace std;
   
    Shader::Shader(const char* vertexPath, const char* fragmentPath)
    {
        ifstream vertexFile;
        ifstream fragmentFile;
   
        stringstream vertexSStream;
        stringstream frangmentSStream;
   
        vertexFile.open(vertexPath);
        fragmentFile.open(fragmentPath);
        vertexFile.exceptions(ifstream::failbit || ifstream::badbit);
        fragmentFile.exceptions(ifstream::failbit || ifstream::badbit);
   
        try
        {
            if (!vertexFile.is_open() || !fragmentFile.is_open())
            {
                throw exception("open File error");
            }
   
            vertexSStream << vertexFile.rdbuf();
            frangmentSStream << fragmentFile.rdbuf();
   
            vertexString = vertexSStream.str();
            fragmentString = frangmentSStream.str();
   
            vertexSource = vertexString.c_str();
            fragmentSource = fragmentString.c_str();
   
            unsigned int vertex, fragment;
   
            vertex = glCreateShader(GL_VERTEX_SHADER);
            glShaderSource(vertex, 1, &vertexSource, NULL);
            glCompileShader(vertex);
   
            fragment = glCreateShader(GL_FRAGMENT_SHADER);
            glShaderSource(fragment, 1, &fragmentSource, NULL);
            glCompileShader(fragment);
   
            ID = glCreateProgram();
            glAttachShader(ID, vertex);
            glAttachShader(ID, fragment);
            glLinkProgram(ID);
            glDeleteShader(vertex);
            glDeleteShader(fragment);
        }
        catch (const exception& e)
        {
            printf(e.what());
        }
    }
   
    void Shader::use()
    {
        glUseProgram(ID);
    }
   

2. Shader.h

    #pragma once
    #include <string>
   
    using namespace std;
    class Shader
    {
    public:
        Shader(const char* vertexPath, const char* fragmentPath);
        //~Shader();
        string vertexString;
        string fragmentString;
        const char* vertexSource;
        const char* fragmentSource;
        unsigned int ID;	// shaderProgram ID
        void use();
    };
   

3. main函数中对应的部分就可以删掉啦

三、收集错误信息

1. 添加一个私有函数checkCompileError

    void Shader::checkCompileError(unsigned int ID,string type)
    {
        int success;
        char infoLog[512];
   
        if (type != "PROGRAM")
        {
            glGetShaderiv(ID, GL_COMPILE_STATUS, &success);
            if (!success)
            {
                glGetShaderInfoLog(ID, 512, NULL, infoLog);;
                cout << "Shader compile error:" << infoLog << endl;
            }
        }
        else
        {
            glGetShaderiv(ID,GL_LINK_STATUS, &success);
            if (!success)
            {
                glGetProgramInfoLog(ID, 512, NULL, infoLog);
                cout << "Program compile error:" << infoLog << endl;
            }
        }
    }
   

2. 放在glCompileShader、glLinkProgram函数之后收集错误信息

(下接 OpenGL入门VII)