[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Gnu3dkit-discuss] matrix multiply of vector

From: Philippe C.D. Robert
Subject: Re: [Gnu3dkit-discuss] matrix multiply of vector
Date: Sat, 6 Jul 2002 18:15:04 +0200

On Friday, July 5, 2002, at 11:53 PM, Brent Gulanowski wrote:
Pursuant to my questions about "Bugs?" on the bug list,

I have a thing I'm trying to do, which I'm sure I'll scrap for an entirely better solution soon, but currently this requires that I apply a scale matrix multiplication to a vector3f. In this case, I want to mirror the vector in the z-axis, and then set the scale of a transform to that vector. It's kind of the wrong application, but assuming I find a use for what is a standard 3D operation, does 3DKit have a way for me to do it properly?

Hmm, I am not entirely sure what you mean... If I get you right then you would multiply your vector with the mirror matrix ( see vectorByPreMultiplying: ) and after that you'd call setScaleValues: on the transform passing your new vector.

The mirror matrix looks like

1  0  0  0
0  1  0  0
0  0 -1  0
0  0  0  1

BTW please be aware that you should always use 4 dimensions when doing 3D graphics, thus you would use a G3DVector4f!

Philippe C.D. Robert

reply via email to

[Prev in Thread] Current Thread [Next in Thread]