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okapota
04-22-2002, 10:51 AM
just intrested to know a few things, if someone knows. i was wandering how were the fur textures generated, and how is it used?
i mean, from what i can see the fur textures are pink and orange and a few more strange colors, but in the demo the fur is brown, so what is going on? i know how to draw fur, i even wrote a little fur app myself, but it looks a bit different there.
and one more thing, what is a dds file format? and nmb for the model? are those nvidia's format, or is it public?

davepermen
04-22-2002, 10:59 AM
i think what you've taken a look at is the normalmap for the bumpiness of the surface..

zeckensack
04-23-2002, 01:05 AM
dds is a DirectX related format. "Direct Draw Surface" IIRC. Search MSDN for a description.

okapota
04-23-2002, 03:49 AM
i thought its something like that, dave, only i thought it was used as some lighting lookup texture, becuase it doent looks like a normal map, and the fur doesnt seem to be bumped.

simongreen
04-23-2002, 12:12 PM
okapota,

The fur textures were generated using a custom in-house tool. We may release this tool in the future if there's any interest.

The textures look wierd because the RGB components represent the per-pixel tangent of each hair strand (i.e. which direction the hair is pointing). This tangent vector is used to light the hair using an approximate anisotropic lighting model in the register combiners. This is what gives the hair that subtle sheen effect.

The alpha components of the texture represent the actual fur density, which is used to blend the layers together. The fur color is controlled by a separate color texture that covers the whole of each surface.

Much of this is based on Jed Lengyel's research at Microsoft. I recommend reading his papers for more information: http://research.microsoft.com/~jedl/

Oh, and you can read the DDS format using the Photoshop plug-in available on our website.

Hope this answers your questions!

-Simon



Originally posted by okapota:
just intrested to know a few things, if someone knows. i was wandering how were the fur textures generated, and how is it used?
i mean, from what i can see the fur textures are pink and orange and a few more strange colors, but in the demo the fur is brown, so what is going on? i know how to draw fur, i even wrote a little fur app myself, but it looks a bit different there.
and one more thing, what is a dds file format? and nmb for the model? are those nvidia's format, or is it public?

okapota
04-24-2002, 03:54 AM
thnx. i read the research about fur rendering. but it seems you took it a little further, very nice. can you give a few more details about that inhouse tool?

simongreen
04-25-2002, 10:35 AM
The fur tool is pretty simple. It uses a particle system based on spherical coordinates to define the hair curves. There are a bunch of sliders that let you tweak the angle, curliness etc, and you can also use procedural noise to add variation. It previews the fur using actual geometry (line strips). Once you have a look you're happy with it it "voxelizes" this geometry into a stack of 2D textures and writes these out to disk.

Our friends at ATI were touting something similar at GDC, but I haven't seen it yet.


Originally posted by okapota:
thnx. i read the research about fur rendering. but it seems you took it a little further, very nice. can you give a few more details about that inhouse tool?

okapota
04-25-2002, 10:56 PM
ok, ill have a look there, one more thing: i saw you have one different hair texture for each part of the body, but only one, so-why does the fur looks curly, if the same tex is used? do u change tex coords? and can this tool preview the fur on the model itself?