OpenGL学习笔记(六)着色器类

编写、编译、管理着色器是件麻烦事。写一个类来让我们的生活轻松一点,它可以从硬盘读取着色器,然后编译并链接它们,并对它们进行错误检测,这就变得很好用了。这也会让你了解该如何封装目前所学的知识到一个抽象对象中。需要把头文件shader加入工程,然后在生成执行文件的目录下新建两个文件分别为顶点着色器和片段着色器的配置文件shader.vs和shader.fs

shader.vs源码

#version 330 core
layout (location = 0) in vec3 aPos; // 位置变量的属性位置值为0

out vec4 vertexColor; // 为片段着色器指定一个颜色输出

void main()
{
    gl_Position = vec4(aPos, 1.0); // 注意我们如何把一个vec3作为vec4的构造器的参数
    vertexColor = vec4(0.5, 0.0, 0.0, 1.0); // 把输出变量设置为暗红色
}

shader.fs源码

#version 330 core
out vec4 FragColor;

in vec4 vertexColor; // 从顶点着色器传来的输入变量(名称相同、类型相同)

void main()
{
    FragColor = vertexColor;
}

头文件shader.h

#ifndef SHADER_H
#define SHADER_H

#include 

#include 
#include 
#include 
#include 

using namespace std;

class Shader {
public:
    unsigned int ID;

    // constructor generates the shader on the fly
    // ------------------------------------------------------------------------
    Shader(const char *vertexPath, const char *fragmentPath) {

//懒汉怎么会新建文件呢...取消下面的注释自动生成shader.vs和shader.fs文件 改权限 复制前面的的配置代码
        /*string filename1 = "3.3shader.vs";
        fstream file1(filename1, fstream::in | fstream::out | fstream::binary);
        if (!file1.is_open()) {
            cout << "FileSystem Init failed" << endl;
        } else {
            cout << "FileSystem Init Success" << endl;
        }
        file1.close();

        string filename2 = "3.3shader.fs";
        fstream file2(filename2, fstream::in | fstream::out | fstream::binary);
        if (!file2.is_open()) {
            cout << "FileSystem Init failed" << endl;
        } else {
            cout << "FileSystem Init Success" <<   endl;
        }
        file2.close();*/

        // 1. retrieve the vertex/fragment source code from filePath
        std::string vertexCode;
        std::string fragmentCode;
        std::ifstream vShaderFile;
        std::ifstream fShaderFile;
        // ensure ifstream objects can throw exceptions:
        vShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
        fShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
        try {
            // open files
            vShaderFile.open(vertexPath);
            fShaderFile.open(fragmentPath);

            std::stringstream vShaderStream, fShaderStream;
            // read file's buffer contents into streams
            vShaderStream << vShaderFile.rdbuf();
            fShaderStream << fShaderFile.rdbuf();
            // close file handlers
            vShaderFile.close();
            fShaderFile.close();
            // convert stream into string
            vertexCode = vShaderStream.str();
            fragmentCode = fShaderStream.str();
        }
        catch (std::ifstream::failure e) {
            std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ" << std::endl;
        }
        const char *vShaderCode = vertexCode.c_str();
        const char *fShaderCode = fragmentCode.c_str();
        // 2. compile shaders
        unsigned int vertex, fragment;
        int success;
        char infoLog[512];
        // vertex shader
        vertex = glCreateShader(GL_VERTEX_SHADER);
        glShaderSource(vertex, 1, &vShaderCode, NULL);
        glCompileShader(vertex);
        checkCompileErrors(vertex, "VERTEX");
        // fragment Shader
        fragment = glCreateShader(GL_FRAGMENT_SHADER);
        glShaderSource(fragment, 1, &fShaderCode, NULL);
        glCompileShader(fragment);
        checkCompileErrors(fragment, "FRAGMENT");
        // shader Program
        ID = glCreateProgram();
        glAttachShader(ID, vertex);
        glAttachShader(ID, fragment);
        glLinkProgram(ID);
        checkCompileErrors(ID, "PROGRAM");
        // delete the shaders as they're linked into our program now and no longer necessary
        glDeleteShader(vertex);
        glDeleteShader(fragment);
    }

    // activate the shader
    // ------------------------------------------------------------------------
    void use() {
        glUseProgram(ID);
    }

    // utility uniform functions
    // ------------------------------------------------------------------------
    void setBool(const std::string &name, bool value) const {
        glUniform1i(glGetUniformLocation(ID, name.c_str()), (int) value);
    }

    // ------------------------------------------------------------------------
    void setInt(const std::string &name, int value) const {
        glUniform1i(glGetUniformLocation(ID, name.c_str()), value);
    }

    // ------------------------------------------------------------------------
    void setFloat(const std::string &name, float value) const {
        glUniform1f(glGetUniformLocation(ID, name.c_str()), value);
    }

private:
    // utility function for checking shader compilation/linking errors.
    // ------------------------------------------------------------------------
    void checkCompileErrors(unsigned int shader, std::string type) {
        int success;
        char infoLog[1024];
        if (type != "PROGRAM") {
            glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
            if (!success) {
                glGetShaderInfoLog(shader, 1024, NULL, infoLog);
                std::cout << "ERROR::SHADER_COMPILATION_ERROR of type: " << type << "\n" << infoLog
                          << "\n -- --------------------------------------------------- -- " << std::endl;
            }
        } else {
            glGetProgramiv(shader, GL_LINK_STATUS, &success);
            if (!success) {
                glGetProgramInfoLog(shader, 1024, NULL, infoLog);
                std::cout << "ERROR::PROGRAM_LINKING_ERROR of type: " << type << "\n" << infoLog
                          << "\n -- --------------------------------------------------- -- " << std::endl;
            }
        }
    }
};

#endif

main函数

#include 
#include 
#include "shader.h"
#include 

void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow *window);

// settings
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;

int main()
{
    // glfw: initialize and configure
    // ------------------------------
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
    if (window == NULL)
    {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);

    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }

    Shader ourShader("/home/czh/CLionProjects/OpenGL_test/cmake-build-debug/3.3shader.vs", "/home/czh/CLionProjects/OpenGL_test/cmake-build-debug/3.3shader.fs");

    float vertices[] = {
            // positions         // colors
            0.5f, -0.5f, 0.0f,  1.0f, 0.0f, 0.0f,  // bottom right
            -0.5f, -0.5f, 0.0f,  0.0f, 1.0f, 0.0f,  // bottom left
            0.0f,  0.5f, 0.0f,  0.0f, 0.0f, 1.0f   // top
    };

    unsigned int VBO, VAO;
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    // bind the Vertex Array Object first, then bind and set vertex buffer(s), and then configure vertex attributes(s).
    glBindVertexArray(VAO);

    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    // position attribute
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    // color attribute
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);

    // You can unbind the VAO afterwards so other VAO calls won't accidentally modify this VAO, but this rarely happens. Modifying other
    // VAOs requires a call to glBindVertexArray anyways so we generally don't unbind VAOs (nor VBOs) when it's not directly necessary.
    // glBindVertexArray(0);


    // render loop
    // -----------
    while (!glfwWindowShouldClose(window))
    {
        // input
        // -----
        processInput(window);

        // render
        // ------
        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

        // render the triangle
        ourShader.use();
        glBindVertexArray(VAO);
        glDrawArrays(GL_TRIANGLES, 0, 3);

        // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
        // -------------------------------------------------------------------------------
        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    // optional: de-allocate all resources once they've outlived their purpose:
    // ------------------------------------------------------------------------
    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);

    // glfw: terminate, clearing all previously allocated GLFW resources.
    // ------------------------------------------------------------------
    glfwTerminate();
    return 0;
}

// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
// ---------------------------------------------------------------------------------------------------------
void processInput(GLFWwindow *window)
{
    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
        glfwSetWindowShouldClose(window, true);
}

// glfw: whenever the window size changed (by OS or user resize) this callback function executes
// ---------------------------------------------------------------------------------------------
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
    // make sure the viewport matches the new window dimensions; note that width and
    // height will be significantly larger than specified on retina displays.
    glViewport(0, 0, width, height);
}

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