GL_ARB_vertex_blend

OpenGL OpenGL: Advanced Coding
1

okay, im just starting out with skinning, and found this extensions that should provide useful.

What i have set up is 2 bones in a rectangle shape box.

i have gone and set the first 4 matrices to be indentity (also tried setting to camera look at matrix)

GL_MODELVIEW0_ARB -> GL_MODELVIEW3_ARB

i have set up my weights, but how do i specify what matrix which weight refers too?

say i have a vertex with 4 weights:
0.5, 0.5, 0.0, 0.0

and bone indexes:
1, 0, 0, 0

so i should get an even blend between bone 0 and 1,
but all vertex blend extension supplies is a weight?

any way, so i set my weights, and identity matrices as i just wanna see my box on screen in its default pos, but i get screwed up polys random when i move the camera?

2

The vertex weighting extension is useless .

3

But this is about the ARB_vertex_blend extension. Which is somewhat less useless than the vertex blend extension, but not by too much.

4

It’s still useless.

I should add, for clarity, that the link I posted also contains a sketch for how you actually want to do it (using software skinning).

If you want to push it on hardware, look into the matrix palette skinning examples in the NVIDIA OpenGL SDK.

5

right im downloading this:
http://developer.nvidia.com/object/sdk_home.html

hope thats what you meant,

as for skinning i got the demo from here:
http://www.ati.com/developer/sdk/RADEONSDK/Html/Samples/OpenGL/VertexBlend.html

which seems to render a whole skinned model in a single draw call?

6

the only OGL skinning sample in thier SDK uses shaders :-/

7

the only OGL skinning sample in thier SDK uses shaders
Yeah, that’s the general idea.

8

hrmm knowing my luck its not gonna work with shaders, so i’d really like to get it working with out, the ATI demo still has me stumped as it looks like they draw thier whole model in 1 draw call :-/

9

ARB_vertex_program is really quite spread, you should give it a try

10

Unless you need to support R100 hardware, I too would suggest using shaders.