Anita Kishore (kishore++at++triavest.com)
Mon, 14 Jul 1997 14:06:59 -0700
I am confused with the following:
I have a Pf application where the channel's view point pos = (x,y,z), and
orientaion = (0,0,0). The graphics object that it is looking at is at the
origin. This object's geode has pre and post draw callbacks. In the pre
callback I do :
- set mmode to mviewing
- push matrix
- getmatrix
- print matrix
As far as I understand, this matrix that I get is a composite transformation
matrix for view point. Which means that its transpose will be of the form:
a11 a12 a13 tx
a21 a22 a23 ty
a31 a32 a33 tz
0 0 0 1
tx, ty, tz are the translation part and the upper LHS 3X3 sub-matrix contains
the rotation and scale parts, right? But eventhough I do not have any rotation
or scale for the view point, the sub-matrix porion has some numbers in it and
when I do pfGetOrthoMatCoord(mat, dst), dst->xyz is fine, just as I set the
view point's position, but dst->hpr shows pitch = -90. Why is this not 0?
Why isn't the above matrix of the form:
1 0 0 tx
0 1 0 ty
0 0 1 tz
0 0 0 1 ???
Another related question is : what is the equivalent of getmatrix() in OpenGL?
The porting guide says GLGet(), but I can't find any man page or info in the
OPenGL book.
Thanks for any insight into this.
-anita
--
Anita Kishore
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