3D textures

[muhkuh]

Hi,

I'm writing a terrain renderer and got some basic texturing working. These textures are generated out a set of detailed textures (rock, grass, debries ...) depending on the height of the terrain at that place.

Now I read about 3D textures at nvidia's home page. If I really understand things I could create a 3D texture with my detailed textures. Transistions between these textures would be created on the fly.

Unfortunatly I just have got a GeForce 2 Pro Board that cannot handles it (except emulated in software). Has anyone tried this yet ? What performance can I expect ?

[nutball]

Originally posted by muhkuh:
Unfortunatly I just have got a GeForce 2 Pro Board that cannot handles it (except emulated in software). Has anyone tried this yet ? What performance can I expect ?

I've tried 3D textures on pre-GF3 nVidia hardware. It's about as fast as I expected, (ie. slow). Can't tell you what frame rate you'd get for your application, but mine was about one frame per second (roughly, I was doing volumetric rendering).

Of course being software emulation it'll depend on the speed of your CPU I suppose...

[dlyttle]

Tried it out on a Radeon 32mb DDR. Unfortunately it was around 8 times slower than normal 2d textures. You also get issues with some banding occuring. If you want to go from a texture at the bottom of your 3d stack to one at the top, then you have to go through all the intervening textures.

rgds

David

[Tom Nuydens]

Be careful packing multiple 2D textures into a 3D one. Mipmapping will cause your images to blend together in the distance. For typical terrain textures, this usually means that your distant mountains turn brown. You can avoid this to some extent by calculating your own mipmaps, but it'll never go away completely.

-- Tom

[muhkuh]

Mmmm, interesting. So still have to use some lowres 2d textures for distant areas. Nevertheless it seems to be a good replacement for splatting.