Co zrobić, żeby obiekt w przestrzeni 3D rotował się razem z kamerą ? (OpenGL)

Question

Cześć. Robię swój pierwszy projekt i napotkałem pewien problem mianowicie, zrobiłem coś takiego, że sześcian znajduje się lekko za kamerą. Robi on za postać gracza. Jest tylko problem, bo gdy obracam się kamerą  o 180 stopni widzę za sobą ten sześcian. Nie wiem w ogóle skąd mogę się dowiedzieć o ile stopni obróciła się kamera. To będzie w funkcji mouse_callback bo nie ukrywam, że dział z kamerą był dla mnie najtrudniejszy i nie wszystko rozumiem na 100%. Jak rozwiązać te problem?

 

C++

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

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

#include <iostream>
#include <fstream>
#include <string>

#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"

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);

float deltaTime = 0.0f;
float lastFrame = 0.0f;
float pitch;
float yaw;
float lastX = 800, lastY = 600;
float fov = 45.0f;

bool firstMouse = true;

static unsigned int CompileShader(unsigned int type, std::string source)
{
    unsigned int id = glCreateShader(type);
    const char* src = source.c_str();
    glShaderSource(id, 1, &src, nullptr);
    glCompileShader(id);

    int result;
    glGetShaderiv(id, GL_COMPILE_STATUS, &result);
    if (result == GL_FALSE)
    {
        int length;
        glGetShaderiv(id, GL_INFO_LOG_LENGTH, &length);
        char* message = (char*)_malloca(length * sizeof(char));
        glGetShaderInfoLog(id, length, &length, message);
        std::cout << "Failed to compile " << (type == GL_VERTEX_SHADER ? "vertex" : "fragment") << "shader" << std::endl;
        std::cout << message << std::endl;
        glDeleteShader(id);

        return 0;

    }

    return id;
}

static unsigned int CreateShader(const std::string& vertexShader, const std::string fragmentShader)
{
    unsigned int program = glCreateProgram();
    unsigned int vs = CompileShader(GL_VERTEX_SHADER, vertexShader);
    unsigned int fs = CompileShader(GL_FRAGMENT_SHADER, fragmentShader);

    glAttachShader(program, vs);
    glAttachShader(program, fs);
    glLinkProgram(program);

    glDeleteShader(vs);
    glDeleteShader(fs);

    return program;
}

std::string readFromFile(const char* pathToFile)
{
    std::string content;
    std::ifstream fileStream(pathToFile, std::ios::in);

    if (!fileStream.is_open()) {
        std::cerr << "Could not read file " << pathToFile << ". File does not exist." << std::endl;
        return "";
    }

    std::string line;
    while (std::getline(fileStream, line)) {
        content.append(line + "\n");
    }

    fileStream.close();
    std::cout << content << std::endl;
    return content;
}

void processInput(GLFWwindow* window)
{

    float currentFrame = glfwGetTime();
    deltaTime = currentFrame - lastFrame;
    lastFrame = currentFrame;

    float cameraSpeed = 2.5f * deltaTime; // dopasuj do swoich potrzeb  
    if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
        cameraPos += cameraSpeed * cameraFront;
    if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
        cameraPos -= cameraSpeed * cameraFront;
    if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
        cameraPos -= glm::normalize(glm::cross(cameraFront, cameraUp)) * cameraSpeed;
    if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
        cameraPos += glm::normalize(glm::cross(cameraFront, cameraUp)) * cameraSpeed;
}

void mouse_callback(GLFWwindow* window, double xpos, double ypos)
{

    if (firstMouse) // ta zmienna bool jest początkowo ustawiona na true  
        if (firstMouse)
        {
            lastX = xpos;
            lastY = ypos;
            firstMouse = false;
        }

    GLfloat xoffset = xpos - lastX;
    GLfloat yoffset = lastY - ypos;
    lastX = xpos;
    lastY = ypos;

    GLfloat sensitivity = 0.05;
    xoffset *= sensitivity;
    yoffset *= sensitivity;

    yaw += xoffset;
    pitch += yoffset;

    if (pitch > 89.0f)
        pitch = 89.0f;
    if (pitch < -89.0f)
        pitch = -89.0f;

    glm::vec3 front;
    front.x = cos(glm::radians(yaw)) * cos(glm::radians(pitch));
    front.y = sin(glm::radians(pitch));
    front.z = sin(glm::radians(yaw)) * cos(glm::radians(pitch));
    cameraFront = glm::normalize(front);

}

void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
    if (fov >= 1.0f && fov <= 45.0f)
        fov -= yoffset;
    if (fov <= 1.0f)
        fov = 1.0f;
    if (fov >= 45.0f)
        fov = 45.0f;
}

int main(void)
{
    GLFWwindow* window;

    /* Initialize the library */
    if (!glfwInit())
        return -1;

    /* Create a windowed mode window and its OpenGL context */
    window = glfwCreateWindow(800, 600, "Shoot The Cube!", NULL, NULL);
    if (!window)
    {
        glfwTerminate();
        return -1;
    }

    /* Make the window's context current */
    glfwMakeContextCurrent(window);

    if (glewInit() != GLEW_OK)
        std::cout << "Error" << std::endl;

    std::cout << glGetString(GL_VERSION) << std::endl;
    glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
    glfwSetCursorPosCallback(window, mouse_callback);

    float vertices[] = {
        -0.5f, -0.5f, -0.5f,    0.0f, 0.0f,
         0.5f, -0.5f, -0.5f,    1.0f, 0.0f,
         0.5f,  0.5f, -0.5f,    1.0f, 1.0f,
         0.5f,  0.5f, -0.5f,    1.0f, 1.0f,
        -0.5f,  0.5f, -0.5f,    0.0f, 1.0f,
        -0.5f, -0.5f, -0.5f,    0.0f, 0.0f,

        -0.5f, -0.5f,  0.5f,    0.0f, 0.0f,
         0.5f, -0.5f,  0.5f,    1.0f, 0.0f,
         0.5f,  0.5f,  0.5f,    1.0f, 1.0f,
         0.5f,  0.5f,  0.5f,    1.0f, 1.0f,
        -0.5f,  0.5f,  0.5f,    0.0f, 1.0f,
        -0.5f, -0.5f,  0.5f,    0.0f, 0.0f,

        -0.5f,  0.5f,  0.5f,    1.0f, 0.0f,
        -0.5f,  0.5f, -0.5f,    1.0f, 1.0f,
        -0.5f, -0.5f, -0.5f,    0.0f, 1.0f,
        -0.5f, -0.5f, -0.5f,    0.0f, 1.0f,
        -0.5f, -0.5f,  0.5f,    0.0f, 0.0f,
        -0.5f,  0.5f,  0.5f,    1.0f, 0.0f,

         0.5f,  0.5f,  0.5f,    1.0f, 0.0f,
         0.5f,  0.5f, -0.5f,    1.0f, 1.0f,
         0.5f, -0.5f, -0.5f,    0.0f, 1.0f,
         0.5f, -0.5f, -0.5f,    0.0f, 1.0f,
         0.5f, -0.5f,  0.5f,    0.0f, 0.0f,
         0.5f,  0.5f,  0.5f,    1.0f, 0.0f,

        -0.5f, -0.5f, -0.5f,    0.0f, 1.0f,
         0.5f, -0.5f, -0.5f,    1.0f, 1.0f,
         0.5f, -0.5f,  0.5f,    1.0f, 0.0f,
         0.5f, -0.5f,  0.5f,    1.0f, 0.0f,
        -0.5f, -0.5f,  0.5f,    0.0f, 0.0f,
        -0.5f, -0.5f, -0.5f,    0.0f, 1.0f,

        -0.5f,  0.5f, -0.5f,    0.0f, 1.0f,
         0.5f,  0.5f, -0.5f,    1.0f, 1.0f,
         0.5f,  0.5f,  0.5f,    1.0f, 0.0f,
         0.5f,  0.5f,  0.5f,    1.0f, 0.0f,
        -0.5f,  0.5f,  0.5f,    0.0f, 0.0f,
        -0.5f,  0.5f, -0.5f,    0.0f, 1.0f
    };

    unsigned int VBO;
    glGenBuffers(1, &VBO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);
    
    std::string vertexShaderSource = readFromFile("vertexShader.shader");
    std::string fragmentShaderSource = readFromFile("fragmentShader.shader");
    unsigned int shaderProgram = CreateShader(vertexShaderSource, fragmentShaderSource);
    glUseProgram(shaderProgram);

    unsigned int bodyTex;
    glGenTextures(1, &bodyTex);
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, bodyTex);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    stbi_set_flip_vertically_on_load(true);
    int width, height, nrChannels;
    unsigned char* data = stbi_load("C:/Users/Antoni/Desktop/container.jpg", &width, &height, &nrChannels, 0);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
    glGenerateMipmap(GL_TEXTURE_2D);
    stbi_image_free(data);

    unsigned int faceTex;
    glGenTextures(1, &faceTex);
    glActiveTexture(GL_TEXTURE1);
    glBindTexture(GL_TEXTURE_2D, faceTex);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    data = stbi_load("C:/Users/Antoni/Desktop/face.png", &width, &height, &nrChannels, 0);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
    glGenerateMipmap(GL_TEXTURE_2D);
    stbi_image_free(data);

    glUniform1i(glGetUniformLocation(shaderProgram, "playerBody"), 0);
    glUniform1i(glGetUniformLocation(shaderProgram, "playerFace"), 1);
   
    glEnable(GL_DEPTH_TEST);

    /* Loop until the user closes the window */
    while (!glfwWindowShouldClose(window))
    {
        /* Render here */
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glClearColor(0.2, 0.5, 1.0, 0.5);

        processInput(window);
        glfwSetScrollCallback(window, scroll_callback);

        float currentFrame = glfwGetTime();
        deltaTime = currentFrame - lastFrame;
        lastFrame = currentFrame;

        glm::mat4 playerCubeLocation(1.0f);
        playerCubeLocation = glm::translate(playerCubeLocation, glm::vec3(cameraPos.x, cameraPos.y - 0.4f, cameraPos.z + 0.63f));
        unsigned int playerLoc = glGetUniformLocation(shaderProgram, "playerCubeLocation");
        glUniformMatrix4fv(playerLoc, 1, GL_FALSE, glm::value_ptr(playerCubeLocation));
        glm::mat4 lookAt(1.0f);
        unsigned int lookAtLoc = glGetUniformLocation(shaderProgram, "lookAt");
        lookAt = glm::lookAt(cameraPos, cameraPos + cameraFront, cameraUp);
        glUniformMatrix4fv(lookAtLoc, 1, GL_FALSE, glm::value_ptr(lookAt));
        glm::mat4 projection(1.0f);
        projection = glm::perspective(glm::radians(fov), (float)800 / (float)600, 0.1f, 100.0f);
        unsigned int projectionLoc = glGetUniformLocation(shaderProgram, "projection");
        glUniformMatrix4fv(projectionLoc, 1, GL_FALSE, glm::value_ptr(projection));

        glDrawArrays(GL_TRIANGLES, 0, 36);

        /* Swap front and back buffers */
        glfwSwapBuffers(window);

        /* Poll for and process events */
        glfwPollEvents();
    }

    glfwTerminate();
    return 0;
}

Vertex shader:

#version 330 core
layout(location = 0) in vec3 PlayerPositions;
layout(location = 1) in vec2 aCords;

out vec2 texCords;

uniform mat4 projection;
uniform mat4 lookAt;
uniform mat4 playerCubeLocation;

void main()
{
	gl_Position = projection * lookAt * playerCubeLocation  * vec4(PlayerPositions, 1.0);
	texCords = aCords;
}

Fragment shader:

#version 330 core

out vec4 Color;
in vec2 texCords;

uniform sampler2D playerBody;
uniform sampler2D playerFace;

void main()
{
	Color = mix(texture(playerBody, texCords), texture(playerFace, texCords), 0.2);
}