Hi,

I'm having problems trying to translate an OpenFrameworks example to Processing, here is the original OF code (it is a basic arcball example)

https://github.com/obviousjim/OFQuaternionExamples/blob/master/ArcballExample/src/testApp.cpp

And here is my translation using toxiclibs Quaternion class:

1. import toxi.geom.*;
2. 
   
3. Quaternion curRot = new Quaternion( 1, 0, 0, 0 );
4. 
   
5. Vec2D lastMouse = new Vec2D( 0, 0 );
6. 
   
7. 
   
8. void setup() {
9.       size( 640, 480, P3D );
10. }
11. 
    
12. 
    
13. void draw() {
14.       background( 200 );
15. 
    
16.       float[] axisAngle = curRot.toAxisAngle();
17. 
    
18.       pushMatrix();
19.       translate( width / 2, height / 2, 40 );
20.       rotate( degrees( axisAngle[0] ), axisAngle[1], axisAngle[2], axisAngle[3] );
21.       noFill();
22.       box( 100 );
23.       popMatrix();
24. }
25. 
    
26. 
    
27. void mousePressed() {
28.       lastMouse.set( mouseX, mouseY );
29. }
30. 
    
31. 
    
32. void mouseDragged() {
33.       Vec2D mouse = new Vec2D( mouseX, mouseY );
34. 
    
35.       Quaternion yRot = new Quaternion( mouse.x - lastMouse.x, 0, 1, 0 );
36.       Quaternion xRot = new Quaternion( mouse.y - lastMouse.y, 1, 0, 0 );
37.       Quaternion rot = yRot.multiply( xRot );
38.       
39.       curRot = curRot.multiply( rot );
40. 
    
41.       lastMouse = mouse;
42. }

When I click and drag to rotate weird stuff happens, any ideas how to fix this?