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celtics
02-09-2010, 12:48 PM
Hi All,

Sorry for my English...

I'm new to OpenGL and I study it from several books.
There is something I'm not understand and I'll appreciate your help. When I want to draw real life vertices do I pass to glVertex3f the real worl coordinates or eye coordiantes (after I do the transformation myself) because I aslo need to specify the viewing volume and the viewing volume is in eye coordinates. What I'm trying to say is how can I specify viewing volume with respect to eye coordinates when when my object (or vertices) are in world coordinates?

Thank u in advance
Eyal

glfreak
02-09-2010, 02:43 PM
Transform the bounding box coordinates using the same view matrix.

You need to pass object vertices in world coordinates and let openGL pipeline do the rest by specifying the model-view matrix.

The BB transformation is something u can do in software and it's cheap. Unless u want to view it, u may pass it in world coords as well.

Have OpenGL 3.0? Use transform feedback.

celtics
02-10-2010, 02:39 AM
Thank u for your answer
I don't want to calculate BB...I'm trying to avoid it.
You wrote :
"You need to pass object vertices in world coordinates and let openGL pipeline do the rest by specifying the model-view matrix."

it's ok by me but who I'll know the clipping plane coordinates since its in eye coordinates and not world coordinates so I might cull objects that I won't want them to be culled. Am I right?

Thank u in advance
Eyal