RE: [Algorithms] Rotating UVs part II

[Awen L. <ali...@ed...>]

Oups: center your UV coords: substract 0.5, and add it again after
computation
	x'=x-.5f
	y'=y-.5f
	x''=rotate x'
	y''=rotate y'
	x_final=x''+.5f
	y_final=y''+.5f
I personnaly concatenate all computations (why only rotations, do use
scale/shear/translate/noisify) via 3x2 matrices)

Note: If you 'frame' your texture, using many pictures in a texture (it can
be your method) for animation/randomization purposes, be aware that your
rotations may show some parts of adjacent frames.


-----Message d'origine-----
De : gda...@li...
[mailto:gda...@li...]De la part de Odin
Jensen
Envoye : lundi 30 septembre 2002 16:12
A : gda...@li...
Objet : [Algorithms] Rotating UVs part II


Ok. Now I got the rotation perfekt. Only it gets translated as well.
I want it to stay centered and not move about :)

Here's my test code

float fUV[8] = {0,0,1,0,0,1,1,1};
float fAngle = DEG2RAD(tTime.GetTime()*60.0f);

for (int iUV = 0; iUV < 8; iUV+=2)
{
float fNewU = fUV[iUV + 0];
float fNewV = fUV[iUV + 1];
fUV[iUV + 0] = (fNewU * cos(fAngle) - fNewV * sin(fAngle));
fUV[iUV + 1] = (fNewU * sin(fAngle) + fNewV * cos(fAngle));
}

I',m not really sure where I messed up.
If I add 0.5f after each UV calculation it gets centered around the top
left corner and I just can't figure out how to center it.

Thanks

Odin



-------------------------------------------------------
This sf.net email is sponsored by:ThinkGeek
Welcome to geek heaven.
http://thinkgeek.com/sf
_______________________________________________
GDAlgorithms-list mailing list
GDA...@li...
https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list
Archives:
http://sourceforge.net/mailarchive/forum.php?forum_id=6188