using quaternions, does

TRANSLATE + ROTATE == ROTATE + TRANSLATE

also, are opengl’s matrices a matrix form of

quaternions

using quaternions, does

TRANSLATE + ROTATE == ROTATE + TRANSLATE

also, are opengl’s matrices a matrix form of

quaternions

>using quaternions, does

>

> TRANSLATE + ROTATE == ROTATE + TRANSLATE

>

No. This is nothing to do with quaternions - it’s a general property of rotations and translations. Also, there’s no way to express a translation using a quaternion.

>also, are opengl’s matrices a matrix form of

>quaternions

No. A quaternion describes an orientation/rotation, nothing more. A 4x4 matrix (as used by OpenGL) can describe such things as rotation, translation, shearing, perspective projection etc.

how can. or are, quaternions be used in computer graphics…the concept that is.

[This message has been edited by xerid (edited 03-02-2000).]

They’re usually used for skeletal animation, mainly because it’s a lot easier to blend between two quaternions than it is using matrices.

Xerid: Quaternions are a good way of representing rotations, however they are hard to visualize (bad for finding a bug ). Their is a TON of info on the net regarding quaternions, definately look into it more.

Oh also a really awsome site that I would like to plug is Ask Dr. Math (www.askdrmath.com). Very useful for almost every algorithm / problem you might come upon, and its solution is explained very well. Great questions/answers pertaining to quaternion numbers as well.

Originally posted by Nathan d’Obrenan:

[b]Xerid: Quaternions are a good way of representing rotations, however they are hard to visualize (bad for finding a bug ). Their is a TON of info on the net regarding quaternions, definately look into it more.

Oh also a really awsome site that I would like to plug is Ask Dr. Math (www.askdrmath.com). Very useful for almost every algorithm / problem you might come upon, and its solution is explained very well. Great questions/answers pertaining to quaternion numbers as well.[/b]

do you have a si,ple example of using quaternions (source code) verses OGL matrices.

also, it seemd that quaternions would be faster, and does that completely throw out OGL matrices.

Just to give an idea, Tomb Raider uses quaternions to smooth the rotations of the camera tracking Lara. The smooth effect is achieved by interpolations.

Xerid: Sorry, right now I don’t. I have just been way to busy, but I do plan to have a kind of personal programming page up soon. I just thought of it now, but I think that it would be real cool if I posted little advanved math tutorials or something with little demo programs. The best advice I can offer re: quaternions is to read books, surf the web a bit and really just experiment on your own (Kind of like everything else in life Its only math!