Mentalray Light-Wrap Model ?


#1

I am having trouble finding any recourse or materials for Mentalray that does light wrapping… can someone please point me somewhere.


#2

There are a couple of custom shaders for mr that do it.


#3

Cim could you possibly show me where to find them, im having serious issuses finding them.


#4

here’s one courtesy of Jan Sandstrom from http://www.sandstrom.on.to (seems to be down)
Hope that helps


#5

#6

thx dudders, i just tried that one and it seems to give a chunky light wrap ish effect. i dunno why.


#7

you should be able to achieve the desired effect you’ll have to fiddle with attributes a bit, maybe your lights are effecting it strangely??


#8

i will try another light type i guess.


#9

doesnt work with shadows at allf or me, gets wierd effects.


#10

The shader on the Pixero’s site is the compiled version of the shader on the nanomation.co.uk. This shader simply reposition normals (sort of) to get more light. I’ve tried to implement this idea (but I’ve really changed normals) for Oren-Nayar shader. This model works OK if lights don’t cast shadows. When the shadows turned on, you see a hard edge between lighter and darker side. I believe the problem is self shadows. When the point currently rendered doesn’t see the light source at all and only gets light because of wrap, object shadowing itself. I don’t know how this problem can be solved. I’ve sent a mail to mental images mailing list, but couldn’t get any reply.


#11

I have compiled a phong wraplight shader with the help of www.nanomation.com
There seem to be something wrong with the sandstrom.on.to redirection adress to my site at the moment but you can still access it at the original adress: http://w1.702.comhem.se/~u70208061/index.html


#12

Just to prevent misunderstanding: i didn’t say this to offend you, you’re doing a great job with compiling/porting all those shaders.

After a little more Google: It seems my theory is correct, and renderman implementation has same problem.


#13

Augustus, No offence taken. Some time ago I found another Wraplight shader by theBigMuh.

I´ve written the mi file and melscript for it. Havent used it much yet but you can try it and see if it works any different.

Since I have forgotten where I first found it, (probably in a post somewhere at the xsibase forum) Im posting the complete package with all files for Maya.

Get it here: http://w1.702.comhem.se/~u70208061/files/theBigMuhs_Wraplight.zip


#14

thx pixero, and agustus. you guys do work that intrest me. i have a hige amount of programming history. If i ever finnish this reel i would really like to get into mentalray shader development.


#15

seems to be prommising, my only issue is i cant get it working =P something about the light linking stuff. i have lights connceted but still no render. Steven has managed to get it working. if its the same version ?


#16

nevermind i found my ignorance in the maya.rc file lol


#17

Works with defualt values, as soon as i change a value in the node it crashes when i click render, with a memory read error. but the shader works without any adjusments. ??? could this be fixed ?


#18

works great now, turns out to be the light linking. I did figure out a way to create a shadow effect over a lightwrapped surface in one pass.

Example : If your connect a SSS node to a lightwrapped nodes ambience it will diffuse to black in the shadow ares, because SSS doesnt scatter where light is absent. creating a shadow effect over a lightwrapped surface. but sicne the light wrap i use crashes with light linking i cannot use this as a workaround.


#19

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