Clipping question

[eckiller]

If an object is clipped, is it not processed for rendering? Thus if i make a virtual world and there are objects behind me that i can't see. Are they not rendered? By render i mean processed or does opengl know to eliminate the geometry?

[Gorg]

You are right about the clipping definition. If something is clipped, it is not rendered.

Opengl Clips the vertices that are outside the view frustrum. But any other vertices will not. So you'll have to make your own clipping algoritms for the vertices that are inside the view frustum.

there are different methods: Bsp(binary space partition trees), octrees and a bunch of others wich are all well documented on the web.


[This message has been edited by Gorg (edited 03-27-2000).]

[AndersO]

You still might want to cull objects wich you know aren't within the viewfrustum.

Cheers

[FATBUDDHA]

Geometry calculations will be performed for all polygons in the scene (at each vertex), wether the polygon is clipped or not.

OpenGL has to perform these geometry calculations, before it knows wether to try rendering the polygon to screen or not.

[Gorg]

oh Sorry!!! You are right. Big Mistake! That makes me look good !

(I promise I will never answer to a thread after 3 am!!!) Sorry about misleading everyone!!!

[This message has been edited by Gorg (edited 03-28-2000).]