1.2.1 Visual studio-OpenGL 官方教程画一个三角形

主要介绍OpenGL官网教程tutorial 02 第一个三角形。涉及到VAO、VBO、着色器、屏幕坐标系等基本概念和相关函数。

视频参考网址:

源码生成: https://b23.tv/SAgQmCB 

源码释义： https://b23.tv/vV3fLQ4

OpenGL教程网址: http://www.opengl-tutorial.org/

主程序（.cpp）代码为：

#include 
#include 
#include 
#include 
#include 

using namespace glm;


// An array of 3 vectors which represents 3 vertices
static const GLfloat g_vertex_buffer_data[] = {
   -1.0f, -1.0f, 0.0f,
   1.0f, -1.0f, 0.0f,
   0.0f,  1.0f, 0.0f,
};

int main() {
    // Initialise GLFW
    glewExperimental = true; // Needed for core profile
    if (!glfwInit())
    {
        fprintf(stderr, "Failed to initialize GLFW\n");
        return -1;
    }
    glfwWindowHint(GLFW_SAMPLES, 4); // 4x antialiasing
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); // We want OpenGL 3.3
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // To make MacOS happy; should not be needed
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); // We don't want the old OpenGL 

    // Open a window and create its OpenGL context
    GLFWwindow* window; // (In the accompanying source code, this variable is global for simplicity)
    window = glfwCreateWindow(1024, 768, "Tutorial 01", NULL, NULL);
    if (window == NULL) {
        fprintf(stderr, "Failed to open GLFW window. If you have an Intel GPU, they are not 3.3 compatible. Try the 2.1 version of the tutorials.\n");
        glfwTerminate();
        return -1;
    }

    

    glfwMakeContextCurrent(window); // Initialize GLEW
    glewExperimental = true; // Needed in core profile
    if (glewInit() != GLEW_OK) {
        fprintf(stderr, "Failed to initialize GLEW\n");
        return -1;
    }

    GLuint VertexArrayID;
    glGenVertexArrays(1, &VertexArrayID);
    glBindVertexArray(VertexArrayID);

    // This will identify our vertex buffer
    GLuint vertexbuffer;
    // Generate 1 buffer, put the resulting identifier in vertexbuffer
    glGenBuffers(1, &vertexbuffer);
    // The following commands will talk about our 'vertexbuffer' buffer
    glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
    // Give our vertices to OpenGL.
    glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertex_buffer_data), g_vertex_buffer_data, GL_STATIC_DRAW);
  //  glBindBuffer(GL_ARRAY_BUFFER, 0);
    glEnableVertexAttribArray(0);
    glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
    glVertexAttribPointer(
        0,                  // attribute 0. No particular reason for 0, but must match the layout in the shader.
        3,                  // size
        GL_FLOAT,           // type
        GL_FALSE,           // normalized?
        0,                  // stride
        (void*)0            // array buffer offset
    );

    glfwSetInputMode(window, GLFW_STICKY_KEYS, GL_TRUE);

    do {
        // Clear the screen. It's not mentioned before Tutorial 02, but it can cause flickering, so it's there nonetheless.
        glClear(GL_COLOR_BUFFER_BIT);

        // Draw nothing, see you in tutorial 2 !
        // 1st attribute buffer : vertices
       
        // Draw the triangle !
        glDrawArrays(GL_TRIANGLES, 0, 3); // Starting from vertex 0; 3 vertices total -> 1 triangle
       

        // Swap buffers
        glfwSwapBuffers(window);
        glfwPollEvents(); 

    } // Check if the ESC key was pressed or the window was closed
    while (glfwGetKey(window, GLFW_KEY_ESCAPE) != GLFW_PRESS &&
        glfwWindowShouldClose(window) == 0);

    glDisableVertexAttribArray(0);
}

运行结果：