Multitexturing with GL_ARB_multitexture

[nebrown1]

I am getting an "invalid operation" message error from my OGL error checking code whenever I use more than 2 textures--specifically when I use the glActiveTextureARB(GL_TEXTURE2_ARB) command. All three texture are there and seem to be working fine--why am I still getting these error messages?

[Kosta]

Originally posted by nebrown1:
I am getting an "invalid operation" message error from my OGL error checking code whenever I use more than 2 textures--specifically when I use the glActiveTextureARB(GL_TEXTURE2_ARB) command. All three texture are there and seem to be working fine--why am I still getting these error messages?

You have to check how much texture units you can use:
GLint maxUnits = 0;
glGetIntegerv(GL_MAX_TEXTURE_UNITS_ARB, &maxUnits);

You can use at most "maxUnits" texture Units!

Kosta

[nebrown1]

Thanks for the help. Sure enough, I only have 2 textures available. Why is that? Is it because of my video card, OpenGL version, or what?

[dmy]

mainly it depends on the card.
multitexturing, to be fast and efficent, has to be performed in hardware.
the tnt/tnt2 has a 2-stage texture pipeline, so it can at most perform a blend between two textures in a single pass.
if i'm not wrong, the nv10 (geforce) has a 4-stage pipeline.

however, opengl supports at most 32 textures, ranging from unit 0 to unit 31.

Dolo/\/\ightY

[cass]

GeForce only has 2 texture units as well. I don't know of any hardware that supports more than 2 units right now. Interesting question, though.

[dmy]

good to know!
creative said something like "4-pixel pipeline..." and i thought it meant a 4-unit multitexturing capability, but i didn't took the time to test...

Dolo/\/\ightY

[This message has been edited by dmy (edited 03-16-2000).]

[ET3D]

The Radeon has 3 texture units. The Kryo and Kryo 2 can multitexture with as many as 8 textures (although they only have 2 units) - don't know how many they allow in OpenGL, though. I think that the pixel shaders on the GeForce3 can allow for quite a few texture stages, but again, I don't know if this is implemented directly (or only through NV extensions).

[BwB]

This is REALLY off topic but the Flipper supports 8 texture units at once in hardware AND its rumored to support OpenGL (thats a very loose rumor at this point though). For those that are unaware, the Flipper is the GameCube's GPU....



[This message has been edited by BwB (edited 03-19-2001).]

[Nutty]

Cass, Have you ever seen an mpeg of Nvidia Geforce II GTS promo featuring Bungie's Halo?

In it it states, the geforce 2 can use 8 textures at once??

thought this was a bit mad, as doesn't Geforce 3 only have 4 texture units?

bizarre...

Nutty.

[davepermen]

all have 2 textures in one pas, radeon has 3, gf3 has 4

this is what i know, perhaps there is an other board wich has more.. or less ( voodoo1 didnt had multitexturing, had it? )