OpenGL和GLFW:不绘制多边形

OpenGL and GLFW: Not drawing polygon

本文关键字：绘制多边形 GLFW OpenGL 更新时间：2023-10-16

我能够创建一个窗口并将其清除为所需的颜色。但无法在左下角画一个正方形。

#include <iostream>
#define GLEW_STATIC
#include <GL/glew.h>
#include <GLFW/glfw3.h>
const GLint WIDTH = 720;
const GLint HEIGHT = 480;
int main()
{
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); // Attempts to set to opengl 3.3
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
    glfwWindowHint(GLFW_RESIZABLE, GL_TRUE);
    GLFWwindow *window = glfwCreateWindow(WIDTH, HEIGHT, "Learn OpenGL", nullptr, nullptr);
    int screenWidth, screenHeight;
    glfwGetFramebufferSize(window, &screenWidth, &screenHeight);
    if (nullptr == window)
    {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return EXIT_FAILURE;
    }
    glfwMakeContextCurrent(window);
    glewExperimental = GL_TRUE;
    if (GLEW_OK != glewInit())
    {
        std::cout << "Failed to initialise GLEW" << std::endl;
        return EXIT_FAILURE;
    }
    glViewport(0, 0, screenWidth, screenHeight);
    while (!glfwWindowShouldClose(window))
    {
        glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);
        glColor3f(0.0f, 0.0f, 1.0f);
        glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
        glBegin(GL_POLYGON);
            glVertex3f(0.0, 0.0, 0.0);
            glVertex3f(0.5, 0.0, 0.0);
            glVertex3f(0.5, 0.5, 0.0);
            glVertex3f(0.0, 0.5, 0.0);
        glEnd();
        glFlush();
        glfwSwapBuffers(window);
        glfwPollEvents();
    }
    glfwTerminate();
    return EXIT_SUCCESS;
}

已弃用的固定函数功能（glBegin() et al & the matrix stacks）在核心上下文中不起作用（GLFW_OPENGL_CORE_PROFILE）。

切换到兼容性上下文：

#include <iostream>
#include <GL/glew.h>
#include <GLFW/glfw3.h>
const GLint WIDTH = 720;
const GLint HEIGHT = 480;
int main()
{
    glfwInit();
    glfwWindowHint(GLFW_RESIZABLE, GL_TRUE);
    GLFWwindow *window = glfwCreateWindow(WIDTH, HEIGHT, "Learn OpenGL", nullptr, nullptr);
    int screenWidth, screenHeight;
    glfwGetFramebufferSize(window, &screenWidth, &screenHeight);
    if (nullptr == window)
    {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return EXIT_FAILURE;
    }
    glfwMakeContextCurrent(window);
    glewExperimental = GL_TRUE;
    if (GLEW_OK != glewInit())
    {
        std::cout << "Failed to initialise GLEW" << std::endl;
        return EXIT_FAILURE;
    }
    glViewport(0, 0, screenWidth, screenHeight);
    while (!glfwWindowShouldClose(window))
    {
        glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);
        glMatrixMode( GL_PROJECTION );
        glLoadIdentity();
        glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
        glMatrixMode( GL_MODELVIEW );
        glLoadIdentity();
        glColor3f(0.0f, 0.0f, 1.0f);
        glBegin(GL_POLYGON);
            glVertex3f(0.0, 0.0, 0.0);
            glVertex3f(0.5, 0.0, 0.0);
            glVertex3f(0.5, 0.5, 0.0);
            glVertex3f(0.0, 0.5, 0.0);
        glEnd();
        glfwSwapBuffers(window);
        glfwPollEvents();
    }
    glfwTerminate();
    return EXIT_SUCCESS;
}

或者提供一些着色器并使用VAO和VBO上传您的几何体。