null material with bidirectional

brancalion · Post by **brancalion** » Tue May 08, 2007 10:46 pm

hi guys! i hope you can help me. I want to render a scene with a null material but i have a problem. if i activate bidirectional the null material casts a little bit of shadows. if i turn off the bidirectional option it doesn't happen. Is it normal? and can i have realistic caustics if idon't use bidirectional?
Thanx
Federico

DaveC · Post by **DaveC** » Tue May 08, 2007 10:49 pm

You will achieve exactly the same caustics without bidirectional. There is, of course, the remote possibility that it may take for ever for them to appear. But, left long enough, they will be there.

StompinTom · Post by **StompinTom** » Wed May 09, 2007 1:09 am

brancalion wrote:hi guys! i hope you can help me. I want to render a scene with a null material but i have a problem. if i activate bidirectional the null material casts a little bit of shadows. if i turn off the bidirectional option it doesn't happen. Is it normal? and can i have realistic caustics if idon't use bidirectional?
Thanx
Federico

You will achieve exactly the same caustics without bidirectional. There is, of course, the remote possibility that it may take for ever for them to appear. But, left long enough, they will be there.

what? re-read the post.

as far as i know a null material is just supposed to be a void so it shouldnt cast shadows regardless of whether or not bidir is on or off.

brancalion · Post by **brancalion** » Wed May 09, 2007 5:10 am

yes i know...but that's what happens! help. any idea?
Federico

DaveC · Post by **DaveC** » Wed May 09, 2007 5:20 am

@stompintom

I was only referring to the point on caustics. Sorry, I should have made that more clear. You are correct about the shadows problem. I believe Nick is working to fix it already.

brancalion · Post by **brancalion** » Wed May 09, 2007 5:21 am

thanx. Federico

null material with bidirectional

null material with bidirectional

Re: null material with bidirectional