我对 OpenGL 和 3D 编程相当陌生，但我已经开始根据http://www.cprogramming.com/tutorial/3d/quaternions.html的教程使用四元数来实现相机旋转。这都是使用 JOGL 用 Java 编写的。
我意识到这类问题被问了很多，但我一直在寻找，找不到有效的解决方案，所以我认为这可能是我的代码的问题。
所以问题是如果我在一个或多个轴上进行两次不同的连续旋转，就会出现抖动和奇怪的旋转。沿 a 轴的第一次旋转，无论是负向还是正向，都可以正常工作。但是，如果我沿 a 轴正向旋转，然后在该轴上负向旋转，则旋转将前后抖动，就好像它在进行正向和负向旋转之间交替一样。
如果我自动旋转（例如向左旋转 500 次，然后向右旋转 500 次），那么它似乎工作正常，这让我认为这可能与按键有关。但是，如果我绕 x 轴旋转然后绕 y 轴旋转，旋转也是不正确的（因为没有更好的词）。
无论如何，我有一个渲染器类，带有以下用于绘制“场景节点”的显示循环：
private void render(GLAutoDrawable drawable) {
GL2 gl = drawable.getGL().getGL2();
gl.glClear(GL2.GL_COLOR_BUFFER_BIT | GL2.GL_DEPTH_BUFFER_BIT);
gl.glMatrixMode(GL2.GL_PROJECTION);
gl.glLoadIdentity();
glu.gluPerspective(70, Constants.viewWidth / Constants.viewHeight, 0.1, 30000);
gl.glScalef(1.0f, -1.0f, 1.0f); //flip the y axis
gl.glMatrixMode(GL2.GL_MODELVIEW);
gl.glLoadIdentity();
camera.rotateCamera();
glu.gluLookAt(camera.getCamX(), camera.getCamY(), camera.getCamZ(), camera.getViewX(), camera.getViewY(), camera.getViewZ(), 0, 1, 0);
drawSceneNodes(gl);
}
private void drawSceneNodes(GL2 gl) {
if (currentEvent != null) {
ArrayList<SceneNode> sceneNodes = currentEvent.getSceneNodes();
for (SceneNode sceneNode : sceneNodes) {
sceneNode.update(gl);
}
}
if (renderQueue.size() > 0) {
currentEvent = renderQueue.remove(0);
}
}
旋转在相机类中执行如下：
public class Camera {
private double width;
private double height;
private double rotation = 0;
private Vector3D cam = new Vector3D(0, 0, 0);
private Vector3D view = new Vector3D(0, 0, 0);
private Vector3D axis = new Vector3D(0, 0, 0);
private Rotation total = new Rotation(0, 0, 0, 1, true);
public Camera(GL2 gl, Vector3D cam, Vector3D view, int width, int height) {
this.cam = cam;
this.view = view;
this.width = width;
this.height = height;
}
public void rotateCamera() {
if (rotation != 0) {
//generate local quaternion from new axis and new rotation
Rotation local = new Rotation(Math.cos(rotation/2), Math.sin(rotation/2 * axis.getX()), Math.sin(rotation/2 * axis.getY()), Math.sin(rotation/2 * axis.getZ()), true);
//multiply local quaternion and total quaternion
total = total.applyTo(local);
//rotate the position of the camera with the new total quaternion
cam = rotatePoint(cam);
//set next rotation to 0
rotation = 0;
}
}
public Vector3D rotatePoint(Vector3D point) {
//set world centre to origin, i.e. (width/2, height/2, 0) to (0, 0, 0)
point = new Vector3D(point.getX() - width/2, point.getY() - height/2, point.getZ());
//rotate point
point = total.applyTo(point);
//set point in world coordinates, i.e. (0, 0, 0) to (width/2, height/2, 0)
return new Vector3D(point.getX() + width/2, point.getY() + height/2, point.getZ());
}
public void setAxis(Vector3D axis) {
this.axis = axis;
}
public void setRotation(double rotation) {
this.rotation = rotation;
}
}
rotateCamera 方法从新的旋转和先前的旋转生成新的永久四元数，而 rotatePoint 方法只是将一个点乘以从永久四元数生成的旋转矩阵。
旋转轴和旋转角度通过简单的按键设置如下：
@Override
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_W) {
camera.setAxis(new float[] {1, 0, 0});
camera.setRotation(0.1f);
}
if (e.getKeyCode() == KeyEvent.VK_A) {
camera.setAxis(new float[] {0, 1, 0});
camera.setRotation(0.1f);
}
if (e.getKeyCode() == KeyEvent.VK_S) {
camera.setAxis(new float[] {1, 0, 0});
camera.setRotation(-0.1f);
}
if (e.getKeyCode() == KeyEvent.VK_D) {
camera.setAxis(new float[] {0, 1, 0});
camera.setRotation(-0.1f);
}
}
我希望我已经提供了足够的细节。任何帮助将不胜感激。