OpenGL 第一人称相机不移动

Question

我已经在 OpenGL 中创建了一个简单的立方体，并且仍在努力开发一个 FPS 相机来围绕它移动。目前，代码只允许通过 W、A、S、D 键进行左、右、上、下移动。申请代码如下：

#include <iostream>
#include <cmath>

// GLEW
#define GLEW_STATIC
#include <GL/glew.h>

// GLFW
#include <GLFW/glfw3.h>

// GLM Mathematics
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

// Other includes
#include "Shader.h"


// Function prototypes
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
void do_movement();

// Window dimensions
const GLuint WIDTH = 800, HEIGHT = 600;

// Camera
glm::vec3 cameraPos = glm::vec3(0.0f, 0.0f, 3.0f);
glm::vec3 cameraFront = glm::vec3(0.0f, 0.0f, -1.0f);
glm::vec3 cameraUp = glm::vec3(0.0f, 1.0f, 0.0f);
bool keys[1024];

// Deltatime
GLfloat deltaTime = 0.0f;   // Time between current frame and last frame
GLfloat lastFrame = 0.0f;   // Time of last frame

// The MAIN function, from here we start the application and run the game loop
int main()
{
    // Init GLFW
    glfwInit();
    // Set all the required options for GLFW
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);

    // Create a GLFWwindow object that we can use for GLFW's functions
    GLFWwindow* window = glfwCreateWindow(WIDTH, HEIGHT, "LearnOpenGL", nullptr, nullptr);
    glfwMakeContextCurrent(window);

    // Set the required callback functions
    glfwSetKeyCallback(window, key_callback);

    // Set this to true so GLEW knows to use a modern approach to retrieving function pointers and extensions
    glewExperimental = GL_TRUE;
    // Initialize GLEW to setup the OpenGL Function pointers
    glewInit();

    // Define the viewport dimensions
    glViewport(0, 0, WIDTH, HEIGHT);

    //Enable depth test
    glEnable(GL_DEPTH_TEST);


    // Build and compile our shader program
    Shader ourShader("C:/Users/Noel/Documents/Visual Studio 2013/Projects/RoomSim/Vertexshader.vs", "C:/Users/Noel/Documents/Visual Studio 2013/Projects/RoomSim/FragShader.frag");


    // Set up vertex data (and buffer(s)) and attribute pointers
    GLfloat vertices[] = {
        -0.5f, -0.5f, -0.5f,
        0.5f, -0.5f, -0.5f, 
        0.5f, 0.5f, -0.5f, 
        0.5f, 0.5f, -0.5f, 
        -0.5f, 0.5f, -0.5f,
        -0.5f, -0.5f, -0.5f,

        -0.5f, -0.5f, 0.5f,
        0.5f, -0.5f, 0.5f,
        0.5f, 0.5f, 0.5f,
        0.5f, 0.5f, 0.5f,
        -0.5f, 0.5f, 0.5f,
        -0.5f, -0.5f, 0.5f,

        -0.5f, 0.5f, 0.5f,
        -0.5f, 0.5f, -0.5f,
        -0.5f, -0.5f, -0.5f,
        -0.5f, -0.5f, -0.5f,
        -0.5f, -0.5f, 0.5f, 
        -0.5f, 0.5f, 0.5f, 

        0.5f, 0.5f, 0.5f,
        0.5f, 0.5f, -0.5f, 
        0.5f, -0.5f, -0.5f,
        0.5f, -0.5f, -0.5f,
        0.5f, -0.5f, 0.5f, 
        0.5f, 0.5f, 0.5f, 

        -0.5f, -0.5f, -0.5f,
        0.5f, -0.5f, -0.5f,
        0.5f, -0.5f, 0.5f, 
        0.5f, -0.5f, 0.5f, 
        -0.5f, -0.5f, 0.5f,
        -0.5f, -0.5f, -0.5f,

        -0.5f, 0.5f, -0.5f, 
        0.5f, 0.5f, -0.5f, 
        0.5f, 0.5f, 0.5f, 
        0.5f, 0.5f, 0.5f, 
        -0.5f, 0.5f, 0.5f,
        -0.5f, 0.5f, -0.5f,
    };

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

    // Bind the Vertex Array Object first, then bind and set vertex buffer(s) and attribute pointer(s).
    glBindVertexArray(VAO);

    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    //glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    //glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

    // Position attribute
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3* sizeof(GLfloat), (GLvoid*)0);
    glEnableVertexAttribArray(0);
    // Color attribute
    //glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
    //glEnableVertexAttribArray(1);

    glBindVertexArray(0); // Unbind VAO


    // Game loop
    while (!glfwWindowShouldClose(window))
    {
        // Calculate deltatime of current frame
        GLfloat currentFrame = glfwGetTime();
        deltaTime = currentFrame - lastFrame;
        lastFrame = currentFrame;

        // Check if any events have been activiated (key pressed, mouse moved etc.) and call corresponding response functions
        glfwPollEvents();
        do_movement();

        // Render
        // Clear the colorbuffer
        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);

        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        //Transformations
        // Create transformations
        //glm::mat4 transform;
        //transform = glm::translate(transform, glm::vec3(0.5f, -0.5f, 0.0f));
        //transform = glm::rotate(transform, (GLfloat)glfwGetTime() * 50.0f, glm::vec3(0.0f, 0.0f, 1.0f));

        // Get matrix's uniform location and set matrix

        //GLint transformLoc = glGetUniformLocation(ourShader.Program, "transform");

        //glUniformMatrix4fv(transformLoc, 1, GL_FALSE, glm::value_ptr(transform));

        // Draw the triangle
        ourShader.Use();

        // Create transformations
        glm::mat4 model;
        glm::mat4 view;
        glm::mat4 projection;

        //Camera particulars for view
        glm::vec3 cameraPos = glm::vec3(0.0f, 0.0f, 3.0f);
        glm::vec3 cameraFront = glm::vec3(0.0f, 0.0f, -1.0f);
        glm::vec3 cameraUp = glm::vec3(0.0f, 1.0f, 0.0f);

        model = glm::rotate(model, 50.0f, glm::vec3(1.0f, 0.0f, 0.0f));


        view = glm::lookAt(cameraPos, cameraPos + cameraFront, cameraUp);
        projection = glm::perspective(45.0f, (GLfloat)WIDTH / (GLfloat)HEIGHT, 0.1f, 100.0f);

        // Get their uniform location
        GLint modelLoc = glGetUniformLocation(ourShader.Program, "model");
        GLint viewLoc = glGetUniformLocation(ourShader.Program, "view");
        GLint projLoc = glGetUniformLocation(ourShader.Program, "projection");
        glBindVertexArray(VAO);
        // Pass them to the shaders
        glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
        glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));
        glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));


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

        // Swap the screen buffers
        glfwSwapBuffers(window);
    }
    // Properly de-allocate all resources once they've outlived their purpose
    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);

    // Terminate GLFW, clearing any resources allocated by GLFW.
    glfwTerminate();
    return 0;
}

// Is called whenever a key is pressed/released via GLFW
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
{
    if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
        glfwSetWindowShouldClose(window, GL_TRUE);
    if (key >= 0 && key < 1024)
    {
        if (action == GLFW_PRESS)
            keys[key] = true;
        else if (action == GLFW_RELEASE)
            keys[key] = false;
    }
}

void do_movement()
{
    GLfloat cameraSpeed = 5.0f * deltaTime;
    // Camera controls

    if (keys[GLFW_KEY_W])
        cameraPos += cameraSpeed * cameraFront;
    if (keys[GLFW_KEY_S])
        cameraPos -= cameraSpeed * cameraFront;
    if (keys[GLFW_KEY_A])
        cameraPos -= glm::normalize(glm::cross(cameraFront, cameraUp)) * cameraSpeed;
    if (keys[GLFW_KEY_D])
        cameraPos += glm::normalize(glm::cross(cameraFront, cameraUp)) * cameraSpeed;
}

问题是按 W、A、S、D 键什么都没有发生。实现的顶点着色器如下：

#version 330 core
layout(location = 0) in vec3 position;
layout(location = 1) in vec3 color;

out vec3 ourColor;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;

void main()
{
gl_Position = projection * view * model * vec4(position, 1.0f);
    ourColor = color;

}

没有移动可能是什么原因？

Answer 1

您在 while 循环中重新定义了 cameraPos，这会影响您在 doMovement 函数中更新的全局 cameraPos。

只需删除 while 中的声明即可。

Answer 2

有两个名为 cameraPos 的变量：

全局范围内的一个，用于 key_callback
和 main 中的本地（在 while 循环内）设置为常量值并用于创建视图矩阵。

解决方法：去掉main中的局部变量，只用全局变量。

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