当我在OpenGL中调整窗口大小时，有没有办法防止我的窗口内容“移动”

Question

我希望我的窗口内容在我的窗口调整大小时保持居中。 OpenGL（或GLFW）-我不确定哪个-在水平调整大小时确实会产生这种预期的效果，但是当我垂直调整窗口大小时，窗口似乎会显示立方体底部的更多部分。我希望它会像水平调整大小时一样切断立方体，

这是水平调整大小

这是垂直调整大小

注意：我不做任何glViewPort()，否则窗口内容会调整为新的宽度和高度。

有没有办法改变这种行为？这个问题可能是相关的，但我认为这不能解决我的问题。 How to keep the OpenGL viewport in an SDL window stationary ...

#include <iostream>
#include <GL/glew.h>
#include <GL/gl.h>
#include <GLFW/glfw3.h>

#include "../includes/Shader.h"
#include "../includes/Texture.h"
#include "../includes/glm/glm.hpp"


const int SCR_WIDTH = 800;
const int SCR_HEIGHT = 600;

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

void processInput(GLFWwindow *window);

int main() {

    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, "OpenGL", nullptr, nullptr);
    if (window == nullptr) {
        std::cout << "Failed to create window! " << std::endl;
        glfwTerminate();
        return -1;
    }

    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
    glfwMakeContextCurrent(window);

    if (glewInit() != GLEW_OK) {
        std::cout << "Failed to initialize GLEW! " << std::endl;
        glfwTerminate();
        return -1;
    }

    float vertices[] = {
            ...
    };

    unsigned int VAO, VBO;

    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);

    glBindVertexArray(VAO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);

    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(float) * 5, (GLvoid *) nullptr);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 5, (GLvoid *) (sizeof(float) * 3));
    glEnableVertexAttribArray(1);

    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindVertexArray(0);

    Texture texture1("../images/container.jpg");
    Texture texture2("../images/awesomeface.png");

    Shader shader("../shaders/shader.vs", "../shaders/shader.fs");

    shader.use();
    shader.setUniform1i("texture1", 0);
    shader.setUniform1i("texture2", 1);


    while (!glfwWindowShouldClose(window)) {

        processInput(window);

        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
        glEnable(GL_DEPTH_TEST);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        texture1.bind(0);
        texture2.bind(1);

        glm::mat4 model = glm::mat4(1.0f);
        glm::mat4 view = glm::mat4(1.0f);
        glm::mat4 projection = glm::mat4(1.0f);

        model = glm::rotate(model, (float) glfwGetTime(), glm::vec3(1.0f, 0.5f, 0.5f));
        view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f));
        projection = glm::perspective(glm::radians(45.0f), 800.0f/600.0f, 0.1f, 100.0f);

        shader.setUniformMat4("model", model);
        shader.setUniformMat4("view", view);
        shader.setUniformMat4("projection", projection);

        glBindVertexArray(VAO);
        glDrawArrays(GL_TRIANGLES, 0, 36);
        glBindVertexArray(0);

        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);

    glfwTerminate();
    return 0;
}

void framebuffer_size_callback(GLFWwindow *window, int width, int height) {
    //glViewport(0, 0, width, height);
}

void processInput(GLFWwindow *window) {
    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) {
        glfwSetWindowShouldClose(window, true);
    }
}

Answer 1

注意：我不做任何 glViewPort() 否则窗口内容会调整到新的宽度和高度。

这就是问题所在。您需要调整视口。根据视口调整视野：

const float defaultHeight = 600.0f;
const float defaultFov = glm::radians(45.0f);

while (!glfwWindowShouldClose(window)) {

    // [...]

    int vpSize[2];
    glfwGetFramebufferSize(window, &vpSize[0], &vpSize[1]);
    glViewport(0, 0, vpSize[0], vpSize[1]);

    float aspect = (float)vpSize[0] / (float)vpSize[1];
    float fov = asin(sin(defaultFov / 2.0f) * vpSize[1] / defaultHeight) * 2.0f;
    glm::mat4 projection = glm::perspective(fov, aspect, 0.1f, 100.0f);

    // [...]
}