read back transformed vertex coordinates...


Is there any way of reading back the vertex coordinates after specifying a series of affine transformations in OpenGL? If so, how?


I think you want to look into gluProject().

But gluProject() needs the viewport to be specified. I want the coordinates of the transformed vertices in world coordinate, i.e. after model and viewing transformations. I do not want to write a set of transformation routines that do the work that is plausibly be done with OpenGL or related libraries.

As a matter of fact, I am trying to cook up some code to parse scene files; and in the scene file, I can specify transformations on polygons instead of stating the absolute world coordinates of these polygon vertices, presumably for easier modeling.

I need transformed vertex coordinates since that would be easier when I do radiosity algorithm.


Originally posted by endash:
I think you want to look into gluProject().

look into feedback mode, there is an entire chapter in the redbook devoted to feedback and selection