我不能在 OpenGl 中制作一个大小均匀的正方形

Question

我想通过组合 2 个三角形来绘制一个等宽的正方形。

但它似乎总是让我在 x 轴上稍微长一些...

// Include standard headers
#include <stdio.h>
#include <stdlib.h>

// Include GLEW
#include <GL/glew.h>

// Include GLFW
#include <glfw3.h>
GLFWwindow* window;

// Include GLM
#include <glm/glm.hpp>
using namespace glm;

#include <common/shader.hpp>

int main(void)
{
    // Initialise GLFW
    if (!glfwInit())
    {
        fprintf(stderr, "Failed to initialize GLFW\n");
        getchar();
        return -1;
    }

    glfwWindowHint(GLFW_SAMPLES, 4);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 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);

    // Open a window and create its OpenGL context
    window = glfwCreateWindow(1024, 768, "16010600 LEE JEE WOONG  Assignment 1-1", 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");
        getchar();
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);

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

    // Ensure we can capture the escape key being pressed below
    glfwSetInputMode(window, GLFW_STICKY_KEYS, GL_TRUE);

    // Dark blue background
    glClearColor(0.0f, 1.0f, 0.0f, 0.0f);

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

    // Create and compile our GLSL program from the shaders
    GLuint programID = LoadShaders("SimpleVertexShader.vertexshader", "SimpleFragmentShader.fragmentshader");


    static const GLfloat g_vertex_buffer_data[] = {
        -0.50f, -0.50f, 0.0f,
         0.50f, -0.50f, 0.0f,
         0.50f, 0.50f,0.0f,
        -0.50f,  0.50f,0.0f,
    };

    unsigned int indices[] = {
        0 , 1, 2,
        2,3, 0,
    };

    GLuint vertexbuffer;
    glGenBuffers(1, &vertexbuffer);
    glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertex_buffer_data), g_vertex_buffer_data, GL_STATIC_DRAW);

    unsigned int ibo;
    glGenBuffers(1, &ibo);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibo);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, 6*2*sizeof(unsigned int), indices, GL_STATIC_DRAW);

    do {

        // Clear the screen
        glClear(GL_COLOR_BUFFER_BIT);

        // Use our shader
        glUseProgram(programID);

        // 1rst attribute buffer : vertices
        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
        );

        // Draw the triangle !
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr);

        glDisableVertexAttribArray(0);

        // 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);

    // Cleanup VBO
    glDeleteBuffers(1, &vertexbuffer);
    glDeleteVertexArrays(1, &VertexArrayID);
    glDeleteProgram(programID);

    // Close OpenGL window and terminate GLFW
    glfwTerminate();

    return 0;
}

有谁知道为什么？它总是显示略微拉伸的输出..是因为我的屏幕吗？

顺便说一句，这是我上传的代码的大小和输出的屏幕截图。

这个我也查了

Unable to draw a square (same width and height) on screen

但是..这个仍然没有得到任何答案。

Answer 1

我不是专家，但可能因为0.5和-0.5是单位-space坐标，而且因为你的window不是正方形，所以你有一个矩形吗？

我不能在 OpenGl 中制作一个大小均匀的正方形

I can't make an even sized square in OpenGl

c++

opengl

glfw

glm-math