Rotation

Sorry I cannot understand, what you are trying to do
What do you mean on rotating about a point ??

all you have to do is multiply your 3 base vectors (1,0,0), (0,1,0) and (0,0,1) by your rotation matrix (or quaternion, depending on what you used) and there you have it. Transformed vector (1,0,0) will materialize your X axis, etc...

The vectors'' length are still 1, since all rotations are isometric (don''t change vector length).

OTOH, not trying to be mean, but if you can''t figure it out by yourself, you''re probably going to have a hard time doing 3D programming. I mean no malice by saying this ! Read some stuff about spacial geometry and transformations, it''ll always come in handy.

Or maybe I just simply misunderstood the whole question, in which case forgive me.

I am picking a point say (0, 0) and then I specify a rotation say 90 degrees. This case is simple because I can say that (0, 1) is another point at 90 degree rotation from (0, 0), and easily get a vector from the two points. How can I do this for any arbitrary point? Thanks.

Wait I think I got it. If I get the vector from the origin to the point I pick and then rotate that vector by whatever angle I have specified, I will have a vector going from the picked point in the direction of the rotation, am I right?

I think you may have to add/subtract 90 degrees or something.

Zorx (a Puzzle Bobble clone)
Discontinuity (an animation system for POV-Ray)

it was me

And after it you cab express the difference of the two vectors.

[edited by - szinkopa on March 31, 2004 4:34:12 PM]