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How to use a non-standard vertex format?
Author
(Using OpenGL 3.2)
When specifying the vertex format for a VBO using glVertexPointer, glNormalPointer, ect..., you specify the number of components (usually) as well as a data type (short, int, float, or double).
My question is, is there any way to specify data types other than this *very* limited set? In directx for example, I can use half floats as well as numerous compressed types. So I *know* the hardware can do it, but is this functionality exposed in OpenGL?
The data type I'm most interested in using is R10G10B10A2 for my normals, though I don't see any way of specifying this with glNormalPointer...
There's no support for R10G10B10A2 as vtx attribs yet. Though, you can get much nicer precision with 2 half-floats and computing the z.
Btw, you shouldn't be using glVertexPointer/etc with 3.2 .
Btw, you shouldn't be using glVertexPointer/etc with 3.2 .
Half float is sopported : GL_HALF_FLOAT
That other format you mentioned is a texture format. I don't think you can use that as a attribute but you can make such a texture with GL and sample it with a vertex shader.
That other format you mentioned is a texture format. I don't think you can use that as a attribute but you can make such a texture with GL and sample it with a vertex shader.
Quote: Original post by coderchris
So I *know* the hardware can do it, but is this functionality exposed in OpenGL?
Yes, OpenGL has no problems with half-floats for vertex attributes.
Author
Ah ok so I can use halfs, I guess this page is out of date: http://www.opengl.org/sdk/docs/man/xhtml/glVertexPointer.xml
I could use 2 half floats and compute Z, but how will I know which direction its in? Won't I need one more bit to indicate positive or negative?
Unless theres some quick spherical coordinate transformation I can do...
What do I use instead of glVertexPointer?
I could use 2 half floats and compute Z, but how will I know which direction its in? Won't I need one more bit to indicate positive or negative?
Unless theres some quick spherical coordinate transformation I can do...
What do I use instead of glVertexPointer?
BTW, 3.2 Core Profile doesn't have gl*Pointer, only glVertexAttribPointer. Looks you're using the compatibility profile.
Quote: ...and compute Z, but how will I know which direction its in? Won't I need one more bit to indicate positive or negative?
2 ways I recall:
- use a free byte-sized attrib that would have been simple padding anyway. Hard to fit with all shaders.
- add 4.0f to x when encoding and the z<0.0f, detect and subtract the 4.0f when decoding. 3 extra gpu cycles.
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