Shameless plug: You might consider buying the book "OpenGL Distilled" (http://www.opengldistilled.com).
The projection matrix defines the size and shape of the view frustum, but doesn't control its (world coordinate) location or orientation. The modelview matrix is responsible for positioning and orienting the camera in the scene, and therefore by implication, it positions and orients the view frustum in the scene. Another way to look at it is that the modelview matrix places within the view volume the parts of the scene to be viewed. Incoming vertices are multiplied by the modelview matrix, then by the projection matrix. The result is normalized device coordinates in the range -1 to 1 in XYZW. Again I'll mention "OpenGL Distilled", which I believe does a pretty decent job of covering OpenGL coordinate transformations. -Paul > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of > Jean-Sebastien Guay > Sent: Wednesday, November 01, 2006 8:17 AM > To: osg users > Subject: [osg-users] ModelView matrix math explanation > > Hello, > > A bit unrelated to OSG, but still in graphics... Does anyone > have a good reference to the relationship between the > ModelView matrix, the Perspective matrix and the view frustum? > > I remember that it's something like multiplying an object's > vertices by the ModelView matrix brings them in the range > [-1,1] for each axis, or something like that, but I can never > remember. I seem to remember finding a website on the subject > a while back, but I can't find anything now. > > The general goal is to transform a ray the same way as OpenGL > transforms vertices, so that I can make a raytraced picture > that corresponds to the realtime OpenGL rendering. I just > can't seem to remember the details! > > Thanks, > > J-S > -- > ______________________________________________________ > Jean-Sebastien Guay [EMAIL PROTECTED] > http://whitestar02.webhop.org/ > _______________________________________________ > osg-users mailing list > [email protected] > http://openscenegraph.net/mailman/listinfo/osg-users > http://www.openscenegraph.org/ _______________________________________________ osg-users mailing list [email protected] http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/
