PDA

View Full Version : what is vertex buffer rendering/ immediate mode?



wow
01-09-2004, 09:08 PM
I hear some people saying that vertex buffer rendering will be much faster, is it? What are they actually and what is their difference?

And what is rasterization ?

Thx a lot!

mikael_aronsson
01-10-2004, 12:25 AM
Hi !

To put it simple, you store all your vertex data in some memory that is available to the hardware in the graphics card instead of the normal RAM memory (the GPU can not access this memory), AGP or what ever, this means that it can be rendered much faster then if you would have to send all your vertices through the OpenGL pipeline every frame.

There exists a number of ways to do this, the original could only handle compiled/static vertices so once they where put in memory it was pretty fixed and could not be updated in an easy way.

Today there exists solutions to update the data in a dynamic way which makes it much more useful.

Mikael

ZbuffeR
01-10-2004, 03:55 AM
Rasterization is the operation during wich all the geometry described as vector data is 'discretized' as screen pixels.

It is an operation occuring near the end of the pipeline, see : http://msdn.microsoft.com/library/default.asp?url=/library/en-us/opengl/over02_5zl1.asp
and : http://www.cs.wpi.edu/~matt/courses/cs56...enGL%20Pipeline (http://www.cs.wpi.edu/~matt/courses/cs563/talks/OpenGL_Presentation/OpenGL_Presentation.html#OpenGL%20Pipeline)

mikael_aronsson
01-10-2004, 04:45 AM
I cannot figure out what that had to do with his question ?

But this might be useful: http://developer.nvidia.com/object/using_VBOs.html

Mikael

ZbuffeR
01-10-2004, 05:18 AM
Well, he said :

Originally posted by wow:
I hear some people saying that vertex buffer rendering will be much faster, is it? What are they actually and what is their difference?

And what is rasterization ?

Thx a lot!

mikael_aronsson
01-10-2004, 08:21 AM
Oh, sorry, missed that, the first thing you get blind on is your eyes ;o)