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View Full Version : Is it possible using client side vertex attribute with server side vertex attribute?



Mr.Twinsen
12-15-2004, 09:21 AM
Hi, I've a quenstion about VBO and client's state.
I know that using vertex pointer with vbo and using normal pointer without vbo is possible.
Similarily, what I wanna do is using the vertex attribute 2(I mean the generic vertex attribute which is accesible in shader) with vbo and using the vertex attribute 3 without vbo.
In opengl spec 2.0, they said binding point is added to the client state. But I wonder that a separate vertex attribute binding point exists for the generic vertex attributes - for example,
GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING_2 and GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING_3
I think this make sense but I can not be sure just looking at the glext.h. Only GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING exist. Need any comment thx :-)

Korval
12-15-2004, 11:47 AM
It is possible, but I wouldn't suggest it for performance. It may even be slower than not using VBO's at all, so it's probably not a good idea.

Mr.Twinsen
12-15-2004, 12:47 PM
Thx for the reply.
It's only for the mesh design purposes, not for a serious usages. (if it's prohibited from doing so, I should make it illegal in my class design too). Thx again :-)

idr
12-16-2004, 08:35 PM
As it turns out, a working group is creating the GLX protocol for ARB_vertex_buffer_object now. For any platform that uses "direct rendering", there is likely still benefit from using mixed client-side and server-side data. I don't know of a case where it would be slower than pure client-side memory, but that doesn't mean that such a case doesn't exist.

The one case that we have discovered to be particularly nasty is where some client-side and server-side arrays are mixed with server-side element array data. We will likely update the spec to advise developers to not use server-side element arrays in a mixed client-side / server-side array data configuration.