Opengl Free cam（来自 Learnopengl）到 3rd cam

Posted 2023-02-16

【中文标题】Opengl Free cam（来自 Learnopengl）到 3rd cam

【英文标题】：Opengl Free cam (from Learnopengl) to 3rd cam

【发布时间】：2020-03-12 19:31:26

【问题描述】：

我正在学习opengl并关注learnopengl网站上的教程（https://learnopengl.com/）

有人可以帮我把这个来自learnopengl教程的相机从免费相机转换为第三人称吗？

我试过放物体（角色）的值，但是我不能让相机围绕玩家旋转。只有物体在镜头前走，如果我转向一边，物体会跟着转动，看起来像FPS相机，物体（角色）是武器。

行走代码（键盘）：

void processKeyboard(Camera_Movement direction, float deltaTime)

    frontY = Front.y;//para tirar o freeCamera
    if (cameraStyle == FPS_CAMERA) 
        Front.y = 0;
           

    float velocity = MovementSpeed * deltaTime;

    if (direction == FORWARD)
        Position += Front * velocity;
    if (direction == BACKWARD)
        Position -= Front * velocity;
    if (direction == LEFT)
        Position -= Right * velocity;
    if (direction == RIGHT)
        Position += Right * velocity;

    Front.y = frontY;

鼠标事件：

void processMouseMovement(float xoffset, float yoffset, GLboolean constrainPitch = true)

    xoffset *= MouseSensitivity;
    yoffset *= MouseSensitivity;

    Yaw += xoffset;
    Pitch += yoffset;

    // Make sure that when pitch is out of bounds, screen doesn't get flipped
    if (constrainPitch)
    
        if (Pitch > 89.0f)
            Pitch = 89.0f;
        if (Pitch < -89.0f)
            Pitch = -89.0f;
    

    // Update Front, Right and Up Vectors using the updated Euler angles
    updateCameraVectors();

更新值：

void updateCameraVectors()

    // Calculate the new Front vector
    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));
    Front = glm::normalize(front);
    // Also re-calculate the Right and Up vector
    Right = glm::normalize(glm::cross(Front, WorldUp));  // Normalize the vectors, because their length gets closer to 0 the more you look up or down which results in slower movement.
    Up = glm::normalize(glm::cross(Right, Front));

并使用：

glm::vec3 playerPosition = glm::vec3(Position.x, terrainY, Position.z) + glm::vec3(1, -0.06f, 1)

有没有人经历过这个，谁能帮助我？ 谢谢

【参考方案1】：

这是我用来创建第三人称相机的代码：

float pitch = -Pitch;
// I use a 90.0f offset
// but you can play around with that value to suit your needs
float yaw = Yaw - 90.0f;

// constrain pitch so you don't look from below ground level
if (pitch < 0.0) 
    pitch = 0.0;

    
// algorithm from ThinMatrix video on third person cameras
float distance = 20.0f;
float x = distance * cos(glm::radians(pitch)) * sin(radians(-yaw));
float y = distance * sin(glm::radians(pitch));
float z = distance * cos(glm::radians(pitch)) * cos(glm::radians(yaw));

glm::vec3 tpCamPos = playerPosition + vec3(-x, y, -z);