Hi there ! I''m working on an implementation independent 3D Camera, which returns a View Matrix which can be applied to the Scene. Now sience OpenGL has a Right Handed Coordinate-System, I''m searching a way to transform a Left Handed Matrix into a Right Handed. I''ve tried a matrix[3][3]*=-1 but this gets a very crazy result, which is not correct. is there a matrix which can be multiplied by a left handed matrix to get a right handed one ? or are there other ways to achieve this ? Thanks in advance! Kind regards hansi pirman

try transposing the left-handed matrix.

Hi
As I know, transposing a matrix interchanges the rows and columns in the matrix.
But my problem is the Z Value.
A Positive Z value has a different meaning in a Left Handed and a Right Handed Coordinate System.
I actually want to swap the Z value of the left handed Matrix (*=-1) so that it works for opengl (right handed coordinate system).

Thanks in advance
regards
hansi pirman

Try a diagonal matrix with [1,1,-1,1] on the diagonal.

h = ftan(fov * 0.5f);
w = h * aspectRatio;
zn = near clip
zf = far clip
matrix = /1/w, 0, 0, 0 \
| 0, 1/h, 0, 0 |
| 0, 0, zf/(zn-zf), -1 |
\ 0, 0, zn*zf/(zn-zf), 0 /

This is row major - transpose for column major (GL)

THanks for all the answers again !

@LilBudyWizer:
I tried this. For the movement and all rotation you solution works perfectli. But the whole scene is messed up now.
i see the backsides of all polygons and the front sides are invisible... ??? any idea ?

@Anonymous Poster:
I can follow you explainations, sorry.. (im not so good in all this game math..)
But it looks like you''ve posted a Perspective Matrix..??
but i''m applying my camere to the modelview matrix ...


kind regards
hansi priman

Right handed systems need to cull the polygons the opposite way to a left handed system.

well, it works fine now !
I use LilBudyWizer''s Method, and Anonymous Poster was also right, i had to change the vertex order!

thanks very much !

After searching the Net again, i also found LilBudyWizer''s solution at the oficial OpenGL FAQ:
(http://www.opengl.org/developers/faqs/technical/transformations.htm)

glMatrixMode (GL_MODELVIEW);

glLoadIdentity ();

glScalef (1., 1., -1.);

/* multiply view transforms as usual... */

/* multiply model transforms as usual... */


I now have to give attention to only invert the matrix once !

kind regards
hansi pirman