| Topic: Y rotation matrix?
|
|
 | Y rotation matrix? | |  |
| Poster | : LaughingJack | | Posts | : 1 | | Country | : United Kingdom | | City | : Southampton |
| | | | Posted by LaughingJack on 26/07/2007 at 05:30:28
| | If I understand correctly, the signs are wrong for your rotation about the Y axis. Shouldn't it be:
cos 0 -sin
0 1 0
sin 0 cos
? | |
|
| | | | | | Poster | : oldmasterchu | | Posts | : 1 | | Country | : Hong Kong | | City | : Hong Kong |
| | | | Posted by oldmasterchu on 29/04/2010 at 14:48:43
| | Hello Riemers,
LaughingJack is right. So does the X and Z rotation matrics.
The calculation in the example shows the coordinate rotate 45 degree counter clockwise around Z axis, not the point (10,5,0).
If you rotate the point (10,5,0) 45 degree CCW around Z axis, the rotated point is still in the first quadrant of the XY plane. Its y-value can't be negative. | |
|
| | | | | | Poster | : Anonymous | | Posts | : | | Country | : | | City | : |
| | | | Posted by Anonymous on 26/10/2011 at 15:48:23
| | You are both talking about CCW rotation. But there are 2 directions in which to rotate.
Cos(t) -Sin(t)
Sin(t) Cos(t)
is indeed for rotating CCW.
HOWEVER,
Cos(t) Sin(t)
-Sin(t) Cos(t)
(As shown in the example) rotates CW, which, I believe, would place the the point in the 4th quadrant with a negative Y value. | |
|
|
 | | |  |
|
|
|
If you appreciate the amount of time I spend creating and updating
these pages, feel free to donate -- any amount is welcome !
|
- Website design & DirectX code : Riemer Grootjans -
©2006 Riemer Grootjans
|
|
