在opengl中限制绕x轴旋转

Question

为了好玩，我用 opengl 制作了一个 3d 相机。 它运行良好，除了我无法弄清楚如何限制绕 x 轴旋转的事实。 如果向上滚动太多，向上和向下控件将反转。 我尝试将camFront.y变量限制为任意值，但相机仍会在 x 轴上翻转。

这是我的代码：

#ifndef CAMERA_H
#define CAMERA_H

#include <GL/glew.h>

#include <GLFW/glfw3.h>

#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/quaternion.hpp>
#include <glm/gtx/quaternion.hpp>

#define WORLD_UP glm::vec3(0.0f, 1.0f, 0.0f)

#include <iostream>


enum CamDirection {
    CAM_FORWARD,
    CAM_BACKWARD,
    CAM_LEFT,
    CAM_RIGHT
};


class Camera {
public:
    void cameraUpdate();

    glm::mat4 getViewMatrix();

    Camera();

    Camera(glm::vec3 startPosition);

    void move(CamDirection dir, GLfloat deltaTime);

    void look(double xOffset, double yOffset);

    void update();

private:

    glm::vec3 camPos;
    glm::vec3 camFront;
    glm::vec3 camUp;
    glm::vec3 camRight;

    const GLfloat camSpeed = 5.05f;

};

glm::mat4 Camera::getViewMatrix() {
    return glm::lookAt(camPos, camPos + camFront, camUp);
}

Camera::Camera():
    camPos  (glm::vec3(0.0f, 0.0f,  0.0f)),
    camFront(glm::vec3(0.0f, 0.0f, -1.0f)),
    camUp   (WORLD_UP)
{}

Camera::Camera(glm::vec3 startPos):
    camPos   (startPos),
    camFront (glm::vec3(0.0f, 0.0f, -1.0f)),
    camUp    (WORLD_UP)
{}

void Camera::move(CamDirection dir, GLfloat deltaTime) {
    const GLfloat v = camSpeed * deltaTime;
    if (dir == CAM_FORWARD)
        camPos += v * camFront;
    else if (dir == CAM_BACKWARD)
        camPos -= v * camFront;
    else if (dir == CAM_RIGHT)
        camPos += v * camRight;
    else
        camPos -= v * camRight;
}
void Camera::look(double xOffset, double yOffset) {
    glm::quat startQuat = {0, camFront.x, camFront.y, camFront.z};

    glm::quat rotation = glm::angleAxis((GLfloat)xOffset, glm::vec3(0.0f, 1.0f, 0.0f));
    glm::quat view = startQuat * rotation;

    rotation = glm::angleAxis((GLfloat)yOffset, glm::vec3(-1.0f, 0.0f, 0.0f));
    view = view * rotation;

    camFront = glm::vec3(view.x, view.y, view.z);
    std::cerr << camFront.x << ' ' << camFront.y << ' ' << camFront.z << std::endl;

}

void Camera::update() {
        // Also re-calculate the Right and Up vector
        camRight = glm::normalize(glm::cross(camFront, WORLD_UP));  // Normalize the vectors, because their length gets closer to 0 the more you look up or down which results in slower movement.
        camUp    = glm::normalize(glm::cross(camRight, camFront));
}
#endif // CAMERA_H

我怎样才能解决这个问题？

Answer 1

在将它们分配给camFront之前，您需要限制view.y和view.z值，最大为 89 度，最小为 -89 度。 在 90 度和 -90 度时，它开始反转。 所以一个非常简单的方法可能是，

if(view.y > 89)
{
  view.y = 89;
}
if(view.y < -89)
{
  view.y = -89;
}
if(view.z > 89)
{
  view.z = 89;
}
if(view.z < -89)
{
  view.z = -89;
}