[osg-users] translate transformation on projection matrices

Paul Martz pmartz at skew-matrix.com
Tue Oct 30 17:55:30 PDT 2007


This is just standard multi-camera view tiling as has been done in OpenGL
for years.

In a two-camera configuration, for example, you usually want the left camera
to show you the left part of the view, and the right camera to show you the
right part of the view. You do this by multiplying a translation into the
projection matrix.

If you didn't multiply this translation into the projection matrix, then all
cameras would render the same eye space, and you'd get the same image from
all cameras.

If you tried to do this by modifying the modelview matrix instead of the
projection matrix, the images wouldn't tile seamlessly.
   -Paul


> -----Original Message-----
> From: osg-users-bounces at lists.openscenegraph.org 
> [mailto:osg-users-bounces at lists.openscenegraph.org] On Behalf 
> Of santosh
> Sent: Tuesday, October 30, 2007 2:42 PM
> 
> Hi Guys
> 
> I am not getting the concept of translate transformation on 
> projection matrix. When we add the slave camera in viewer  we 
> have to give projection offset. In osgcamera example the 
> projection offset is given translate transformation matrix. 
> what it exactly does.
> is it translating camera position or rotating the camera?
> 
> Thanks
> Santosh
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