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Transparency to only one object or material
show user profile  CaptainElm
I have no idea how to word this properly to search on Google, so I'm having a bit of trouble.
I'm working on a cell-shaded 3D model with visuals inspired by Wind Waker, but I've run into some trouble with the hair and eyes. In the game the eyes are shown on top of the hair, in typical anime/manga style, but are still behind it, attached to the face. How do I make the hair transparent to only one material/object?
read 742 times
8/30/2012 1:22:46 PM (last edit: 8/30/2012 1:22:46 PM)
show user profile  Weetabix
"Alpha channel"
"Alpha map"

Actually, ignore this. I misread your question.

read 734 times
8/30/2012 1:29:36 PM (last edit: 8/30/2012 1:30:05 PM)
show user profile  CaptainElm
Yeah, I just want the eyes to appear in front of the hair, but for the hair to be in front of the face (obviously the eyes will be attached to the face).

Like this:

read 730 times
8/30/2012 1:32:22 PM (last edit: 8/30/2012 1:33:58 PM)
show user profile  advance-software
you could do that in a real-time (rasterizing) engine using z-bias. basically it modifies the z-buffer calculation for whatever you apply it to, so you can force something artificially to the front. can also use this to compensate for z-fighting in other situations.

no idea if you have that option in a raytracer or whatever you're using.

doesn't look like that needs raytracing anyway.

alternative is to render the eyes out to a seperate layer, then composite in post.
read 726 times
8/30/2012 1:34:50 PM (last edit: 8/30/2012 1:39:33 PM)
show user profile  CaptainElm
It would be highly preferable if I could do this in 3DS Max, instead of another engine. I'm just trying to make a picture, not an in-game model. If it is possible in 3DS Max, I would appreciate some pointers on how to perform this.
read 715 times
8/30/2012 1:44:29 PM (last edit: 8/30/2012 1:44:29 PM)
show user profile  advance-software
so just comp it in layers then.
read 713 times
8/30/2012 1:45:27 PM (last edit: 8/30/2012 1:45:27 PM)
show user profile  herfst1
Cheap fix:

Make your eyes as a seperate object, add an alpha map on the opacity slot. Place them slightly in front of the hair. Done.
read 706 times
8/30/2012 1:50:01 PM (last edit: 8/30/2012 1:50:01 PM)
show user profile  advance-software
that'll make them look like they're floating in front herfst1.
as indeed would be the case - you'd see it when the perspective changes.

could get away with that for a single image but if it's animated it'll look awful.
read 704 times
8/30/2012 1:51:35 PM (last edit: 8/30/2012 1:52:26 PM)
show user profile  CaptainElm
Thanks for the help advance-software, but I'm not too versed in 3DS Max. I can model and render, but that's about it right now. Would you mind letting me know how to comp it in layers?
read 694 times
8/30/2012 2:07:50 PM (last edit: 8/30/2012 2:07:50 PM)
show user profile  advance-software
I'm not exactly a max expert either so am not giving you step by step.

but something like:

render out the eyes on their own - hide everything else. ensure they render with an alpha channel so everything that isn't part of the eye is transparent.

save to a png.

render the rest (eyes hidden), save to a png.

load the main render in photoshop or gimp. load the eyes into a layer over the top - it should have an alpha channel so you can see through to the main render underneath.

something like that. if you need exact step by step, sorry too busy atm. maybe someone else can walk you through it.

if it's an animation, it'll get a bit more tricky as you can't just render the eyes over everything else as they'd appear in front of objects obscuring the character. you'd need to do some depth masking there. ask a pro how to do this as not my field.
read 692 times
8/30/2012 2:24:26 PM (last edit: 8/30/2012 2:25:18 PM)
show user profile  CaptainElm
Oh, I knew how to do that, I thought you were talking about in 3dsmax. I'll probably just have to do that, if it isn't possible any other way. The only problem is that I wouldn't be able to make it animated at all that way... Thanks though.
read 688 times
8/30/2012 2:26:10 PM (last edit: 8/30/2012 2:27:00 PM)
show user profile  advance-software
you can animate that way but you'll need to render out depth maps & use those in the composite or render foreground/background elements.

as to how to use depth in compositing apps, no idea, I don't do it. I'm a real-time guy.

you could fake the z-bias if you composite using depth maps by rendering the eyes seperately & tweaking their depth map slightly.

would imagine there are tutorials around on how to composite using depth maps.

here we go - depth (z) render procedure here :

it just ends up as a grey scale so make the eyes layer slightly brigher than the default to bring them closer depth wise.

the composite in here :

looks like you can do it with nuke, though that's fairly expensive.

would imagine there are others around here who can point you at the easiest depth merged comp solution or whatever you call it.
read 684 times
8/30/2012 2:30:38 PM (last edit: 8/30/2012 2:38:27 PM)
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