NPOT texture dimensions on NV40

OpenGL OpenGL: Advanced Coding
1

Still haven’t gotten my GF 6800 yet…

Does anybody know if there is some cost to using NPOT texture dimensions on NV40? Is texture rectangle still better for things like render to texture?

-Won

PS NPOT = non-power-of-two

2

Depends on how they implemented it in hardware. I don’t think it costs any more than a standard 2D sample though, I mean it’s not a state switch, so it can’t cost more or less.

Edit:
Actually it is kind of a state switch, because the drivers can tell if it’s not power of two, but I still don’t think it would cost more.

3

NPOT is the same speed as regular 2D texturing for GeForce 6800.

Thanks -
Cass

4

Interesting. Recently I changed my pbuffer code to use the GL_TEXTURE_RECTANGLE_NV texture format even if GL_TEXTURE_2D would have work also. NPOT textures appeared to be significantly faster (about 10% in the final application, using a FX5600)

5

Thanks for the authoritative response, Cass.

What about RTT? Is it still better to use texture rectangle or can I just use NPOT?

What about 3D texutres?

-Won

PS looks like I’m getting it next week or so…