Alice Community How do these functions work?

 How do these functions work?
 Rick Prins Guest   Status: Posts: n/a How do these functions work? - 03-13-2008, 09:47 PM Object function "Object's Quaternion" returns 4 coordinates (w,x,y,z). Can someone please explain to me what those coordinates represent? Also, a world function under the "other" category has 3 parameters, right, up and forward. How do those work?
DickBaldwin
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03-14-2008, 12:14 AM

Quote:
 Originally Posted by Rick Prins Object function "Object's Quaternion" returns 4 coordinates (w,x,y,z). Can someone please explain to me what those coordinates represent? Also, a world function under the "other" category has 3 parameters, right, up and forward. How do those work?
Can't help you much with Quaternion. I do know that they are heavily used by game programmers. I believe that they somehow combine coordinate information with orientation information. Apparently they provide computational efficiencies for certain operations. Even if you get a Quaternion in Alice, I don't believe there is much support for doing anything with it.

However, right, up, and forward are simply Alice-speak for the normal X, Y, and Z coordinates of a 3D world. Apparently the Alice development team believed that right, up, and forward would be somewhat less mentally challenging than X, Y, and Z for beginning programming students.

Dick Baldwin
Free Alice tutorials: http://www.dickbaldwin.com/tocalice.htm
Free programming tutorials: http://www.dickbaldwin.com/toc.htm

 DrJim Guest   Status: Posts: n/a 03-15-2008, 10:59 AM For more on quaternions see the thread: http://www.alice.org/community/showt...highlight=roll As I understand it, they simplify the matrix manipulations required to do 3D math, especially if it is heavy in rotations, thus the popularity with game programmers. Doubt if a non-specialist would have much use for them - just a good basic matirx manipulation package should be adequate. They are part of the CMU math pack - but, as Dick noted - I don't think there is any way to directly access that from the current version of Alice.

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