OpenGL学习--开发环境

#include <iostream>  

// GLEW  
#define GLEW_STATIC  
#include <GL/glew.h>  

// GLFW  
#include <GLFW/glfw3.h> 


// Function prototypes  
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);

// Window dimensions  
const GLuint WIDTH = 800, HEIGHT = 600;

// Shaders  
const GLchar* vertexShaderSource = "#version 330 core\n"
"layout (location = 0) in vec3 position;\n"
"void main()\n"
"{\n"
    "gl_Position = vec4(position.x, position.y, position.z, 1.0);\n"
"}\0";
const GLchar* fragmentShaderSource = "#version 330 core\n"
"out vec4 color;\n"
"void main()\n"
"{\n"
    "color = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n"
"}\n\0";

// The MAIN function, from here we start the application and run the game loop  
int main()
{
    std::cout << "Starting GLFW context, OpenGL 3.3" << std::endl;
    // Init GLFW  
    glfwInit();
    // Set all the required options for GLFW  
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);

    // Create a GLFWwindow object that we can use for GLFW‘s functions  
    GLFWwindow* window = glfwCreateWindow(WIDTH, HEIGHT, "LearnOpenGL", nullptr, nullptr);
    glfwMakeContextCurrent(window);

    // Set the required callback functions  
    glfwSetKeyCallback(window, key_callback);

    // Set this to true so GLEW knows to use a modern approach to retrieving function pointers and extensions  
    glewExperimental = GL_TRUE;
    // Initialize GLEW to setup the OpenGL Function pointers  
    glewInit();

    // Define the viewport dimensions  
    int width, height;
    glfwGetFramebufferSize(window, &width, &height);
    glViewport(0, 0, width, height);


    // Build and compile our shader program  
    // Vertex shader  
    GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    glCompileShader(vertexShader);
    // Check for compile time errors  
    GLint success;
    GLchar infoLog[512];
    glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
    }
    // Fragment shader  
    GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
    glCompileShader(fragmentShader);
    // Check for compile time errors  
    glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
    }
    // Link shaders  
    GLuint shaderProgram = glCreateProgram();
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, fragmentShader);
    glLinkProgram(shaderProgram);
    // Check for linking errors  
    glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
    if (!success) {
        glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
    }
    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);


    // Set up vertex data (and buffer(s)) and attribute pointers  
    //GLfloat vertices[] = {  
    //  // First triangle  
    //   0.5f,  0.5f,  // Top Right  
    //   0.5f, -0.5f,  // Bottom Right  
    //  -0.5f,  0.5f,  // Top Left   
    //  // Second triangle  
    //   0.5f, -0.5f,  // Bottom Right  
    //  -0.5f, -0.5f,  // Bottom Left  
    //  -0.5f,  0.5f   // Top Left  
    //};   
    GLfloat vertices[] = {
        0.5f, 0.5f, 0.0f,  // Top Right  
        0.5f, -0.5f, 0.0f,  // Bottom Right  
        -0.5f, -0.5f, 0.0f,  // Bottom Left  
        -0.5f, 0.5f, 0.0f   // Top Left   
    };
    GLuint indices[] = {  // Note that we start from 0!  
        0, 1, 3,  // First Triangle  
        1, 2, 3   // Second Triangle  
    };
    GLuint VBO, VAO, EBO;
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    glGenBuffers(1, &EBO);
    // Bind the Vertex Array Object first, then bind and set vertex buffer(s) and attribute pointer(s).  
    glBindVertexArray(VAO);

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

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(GLfloat), (GLvoid*)0);
    glEnableVertexAttribArray(0);

    glBindBuffer(GL_ARRAY_BUFFER, 0); // Note that this is allowed, the call to glVertexAttribPointer registered VBO as the currently bound vertex buffer object so afterwards we can safely unbind  

    glBindVertexArray(0); // Unbind VAO (it‘s always a good thing to unbind any buffer/array to prevent strange bugs), remember: do NOT unbind the EBO, keep it bound to this VAO  


    // Uncommenting this call will result in wireframe polygons.  
    //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);  

    // Game loop  
    while (!glfwWindowShouldClose(window))
    {
        // Check if any events have been activiated (key pressed, mouse moved etc.) and call corresponding response functions  
        glfwPollEvents();

        // Render  
        // Clear the colorbuffer  
        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

        // Draw our first triangle  
        glUseProgram(shaderProgram);
        glBindVertexArray(VAO);
        //glDrawArrays(GL_TRIANGLES, 0, 6);  
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
        glBindVertexArray(0);

        // Swap the screen buffers  
        glfwSwapBuffers(window);
    }
    // Properly de-allocate all resources once they‘ve outlived their purpose  
    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);
    glDeleteBuffers(1, &EBO);
    // Terminate GLFW, clearing any resources allocated by GLFW.  
    glfwTerminate();
    return 0;
}

// Is called whenever a key is pressed/released via GLFW  
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
{
    if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
        glfwSetWindowShouldClose(window, GL_TRUE);
}