PDA

View Full Version : Shadows based on alpha mask?

foreverendering
07-31-2003, 02:58 PM
Here is a question that I've been wondering about for awhile, maybe someone can clear this up for me.

Is it possible to cause an object to cast a shadow based on its alpha mask rather than its geometry? For example, you could take a plane, then map a leaf texture to it and alpha mask it so that only the leaf is visible. But, the shadow cast is that of the plane.

Is there a workaround for this? This isn't a pressing issue... its more one of those "Can this be done?" type of questions.

Oh, while on the subject of alpha masking, is there a way to cause objects to display their alpha masks in the viewport?

Thanks in advance!
Aearon
07-31-2003, 05:34 PM
so what you want is a partly transparent object but opaque shadows? i have no idea how that would be useful :insane: :shrug: but it's possible of course ;)

i'd duplicate the plane, apply an opaque material to it and disable 'visible' in the object properties.. this way it will just cast a shadow

the other thing: you just have to click the 'show map in viewport button' in the properties of you alpha map
foreverendering
07-31-2003, 05:44 PM
[edited due to my own stupidity]

Never mind, not sure what I was doing wrong before but it works fine by default.

The issue was that I wanted the cast shadow to be the same as my alpha mask, so that it corresponded to the form left by the opacity map. For some reason the first time I tried it I messed up, but I just ran through it again and its working without a hitch...

<smacks head>

Sorry for wasting your time!
Dave Black
07-31-2003, 05:54 PM
Raytraced shadows will give you the effect you are/were looking for, but this can take too long if you are rendering a big scene. Try going here: www.maxplugins.de

In the Max4 section, do a search for the term "xshadow". This will yield the plugin Xshadow from Itoo software. Download, install, and watch your problem disapear.

-3DZ

:D
Rivendale
07-31-2003, 06:11 PM
I think what you did was maybe using area shadows on your light. By default it doesn't produce alpha-shadows, you have to turn on "transparent shadows" under "optimizations" for it to work.
foreverendering
07-31-2003, 07:00 PM
Ahh, that must have been the difference. Second time around I used ray-traced shadows.

Thanks for the clarification guys!

Btw 3DZ I played around with the that noise map for fire last night and although I'm not achieving the exact effect I want I came pretty close... :) thanks

PS : Does anyone know about seeing objects in their alpha masked state in the viewport?
Rivendale
07-31-2003, 07:07 PM
Originally posted by foreverendering

PS : Does anyone know about seeing objects in their alpha masked state in the viewport?
Right-click the viewport label and select Configure...then set transparency to Best. On your material you should have the "Show map in viewport" checkerbox pressed in at the top level of the material.
:p
foreverendering
07-31-2003, 07:20 PM
oh man...

dude you rule!!!
foreverendering
07-31-2003, 07:44 PM
Hey 3DZ,

I downloaded and installed XShadow, then loaded up max. I went to my spotlights modify panel and turned shadows on. Then, from the drop down menu I selected Xshadow.

Scrolling down I see the options "opaque", "from opacity material", and "custom" all under Xshadow 1.72 Shadow Image.

"from opacity material" was selected by default. I tried rendering but it didn't work. I tried the other options but couldn't get any of those to work either... (?) Can you give me a helpful nudge? What am I doing wrong?
CGTalk Moderation
01-15-2006, 06:00 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.