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precedia
04-27-2009, 11:53 AM
Oops. I originally posted this in general discussion rather than here in support.

I need some help with fur rendering on an object that spins upside down.

I have a model of a bat complete with body and hair fur. When I spin the bat upside down so it hangs from its claws, hair on the body disappears.

I have experimented with "Use Dot" and "Dynamic Gravity" per p. 16 of the FiberFX manual with no luck. I assume I am missing something simple (?).

Attached is a proxy model and scene file where I use a capsule to simulate the bat's body.

An animation of the capsule turning upside down is here:

http://www.lanovaz.org/daniel/Docume...Fur/batFur.mov (http://www.lanovaz.org/daniel/Documents/LightWave/Scenes/BatFur/batFur.mov)
http://www.lanovaz.org/daniel/Docume...Fur/batFur.wmv (http://www.lanovaz.org/daniel/Documents/LightWave/Scenes/BatFur/batFur.wmv)

Any advice anyone can offer is appreciated.

Regards,
Daniel

LightWave 9.6 Build 1539 Mac OS X 10.5.6.

adamredwoods
04-27-2009, 12:13 PM
If you are using gravity, that would make sense that it disappears when turned upside down.

I think you would use a bias map, but be warned-- I've heard there are still bugs with bias maps.

precedia
04-27-2009, 12:18 PM
If you are using gravity, that would make sense that it disappears when turned upside down.

I think you would use a bias map, but be warned-- I've heard there are still bugs with bias maps.

Thanks. Same effect whether there is gravity or not.

I will try a bias vmap and see if that helps.

Daniel

precedia
04-27-2009, 06:46 PM
The attached scene I have enabled OpenGL drawing of the hair. I have also disabled gravity.

When you open the scene you should see the capsule with hair extending in all directions.

Simply scrub through the timeline from 0 to 60. As you scrub notice how the hair fibers go all crazy, as if they are losing track of the surface normal or being affected by gravity.

I still have not gotten bias vmaps to work yet. I am trying to avoid using Strand Modeler but there may be no hope.

I am amazed that one can't rotate an object when using the Fiber Filter Pixel Filter. That must be some form of oversight or bug. I have reported this in FogBugz, but I still can't help but think it is (my) user error.

Daniel

IMI
04-27-2009, 09:12 PM
I wish I could help you, but it does the same thing here, and I can't see anything "wrong" with it. Aside from the part of it being all FUBAR and all.
I'm just posting this to confirm the same result.

Welcome to the new and improved FFX...

adamredwoods
04-28-2009, 11:13 AM
Does it happen worst at the 90degree marks? Especially pitch? If so, the fibers calculations are based off euler equations, which would cause problems.

precedia
04-28-2009, 11:13 AM
Thanks for confirming.

Unless 1) I get bias vmaps working, 2) I hear from a FiberFX guru on these forums, or 3) I hear from NewTek through their bug reporting system, I have moved to using the strand modeler.

For those struggling like me, with strand modeler the fibers hold their structure no matter what the rotation, including when the bat is hanging upside down in its preferred posture.

The issue now is that I use weight maps for the bone rig, so now I'm having to go through and ensure the the proper fiber strands are deformed with the proper bone and mesh deformation. NOTE: you get that for free when using the pixel filter on a surface as there were no additional strands to move.

I may throw away weight maps for my bones if it causes too much problem with the strands, but I find them useful to control influence area and falloff. However, this is my first foray into fiber strand (fur) deformation in a rigged/animated model.

Attached is a snapshot of Luna (the main character's pet in my upcoming Gala 2009 animation) taken using my high-speed night camera. :-)

This version is using strand modeler as opposed to strictly using the pixel filter on a surface (note that her protective eyeball membrane is closed in this frame).

I use cloth FX for the skin between the fingers. It actually allows the skin to deform rather nicely when the bat's arms/fingers are animated.

I find the hair looks very different when you switch from pixel filter to strands, but that's most certainly my lack of mastering settings between the two.

Again, thanks for confirming. At least Luna can "hang with her friends" and not feel so naked and cold.

Daniel

precedia
04-28-2009, 11:23 AM
Does it happen worst at the 90degree marks? Especially pitch? If so, the fibers calculations are based off euler equations, which would cause problems.

It seems to be the worst at > 90. For example, when getting close to 180 degrees is when I see fibers completely disappear. The screen shots in my previous post are at 0, 90, and near 180. At 90 they are all goofed but not gone. At near 180 (and 180) they disappear, probably pointing inwards into the mesh.

Daniel

precedia
04-28-2009, 01:05 PM
I think you would use a bias map, but be warned-- I've heard there are still bugs with bias maps.

The bias vmap appears to work for the capsule. With a vmap properly initialized the rotating capsule keeps the hair pointing in the correct position (at least on a small capsule test).

I am now experimenting with the bat mesh, but the color map does not seem to appear on my mesh even after attaching it in the surface property dialog, Advanced tab. The vertex color map does not get carried over to Layout. It appears in Modeler, but not in Layout. Weird. Still researching.

Daniel