当我在 OpenGL 中调整 window 大小时，有没有一种方法可以防止 window 的内容来自 "moving"

Question

我希望我的 window 内容在 window 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能达到预期的效果，但是当我垂直调整 window 大小时，window 似乎显示了立方体底部的更多部分.我希望它能像水平调整大小时那样切断立方体，

这是水平调整大小

这是垂直调整大小

注意：我没有做任何 glViewPort() 否则 window 内容会调整到新的宽度和高度。

有什么办法可以改变这种行为吗？这个问题可能是相关的，但我不认为这能解决我的问题。 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

Note: I do not make any glViewPort() otherwise the window contents would adjust to the new width and height.

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);

    // [...]
}

当我在 OpenGL 中调整 window 大小时，有没有一种方法可以防止 window 的内容来自 "moving"

Is there a way to prevent the contents of my window from "moving" when i resize the window in OpenGL

c++

opengl

viewport

glfw

opengl-3