index buffer swapping (vbos)

OpenGL OpenGL: Advanced Coding
#1

Hello,
I wondered if the following vbo useage idea is fast or slow:

1 static vertex buffer
2 dynamic index buffers

feed index buffer
drawcall
swap index buffer & feed it
drawcall

or would one need to have multiple vertex buffers as well ? (I think not)

thanks for your time

#2

Index buffer will work on whatever vertex buffer is bound. So, yes, this would work.

#3

mh i can’t imagine a case in which you have the same vertex positions but different indices… what do you need this for?

#4

Originally posted by Vexator:
mh i can’t imagine a case in which you have the same vertex positions but different indices… what do you need this for?
Perhaps he needs it for LOD or he has many small objects in one VBO.

#5

the latter is the case, mostly for batching many small objects. so same indices wouldnt be used.

thanks for the info

on a side not, does anyone know if using shorts for normals/texcoords was accelerated on radeon 8500 ? currently I have a fat vertex 64 byte, and a small one with 32 byte (no normals), but I could need normals in the 32byte one too. and our target hardware is older vs1.0 hardware mostly