Transparency/clip map not affecting the backside of the material :(

[Free Agent_cg]

ok i've filled out a couple of those bug report things in the support section (about a few things) and i havnt gotten a reply so i'll try here ,this was one of my favourite things about the original release that no matter what material was on the back of geometry that had clip map applied the texture would project to the otherside, i even used this when there no transparency needed by just applying a complete black image in the transparency field so that when rendered the backside of the material was correct...

of course this now makes rendering xfrog trees (and many other things)unsatisfactory as the reverse faces are screwed on import...

any input?

[thomthom]

Re: Transparency/clip map not affecting the backside of the material

Don't know of any work around, sorry. But good that you mentioned this because I've noticed as well that SU import the XFrog trees with messed up backfaces. I was messing about for a long time trying to find a way to sort that out because I thought V-Ray would render it as seen in SU.

One of my ideas was to ask in the Sketchucation's ruby forum if there was anyone there that could write a plugin that would transfer the correct texture mapping from the front of faces to the backside of faces. I didn't actually make this request as I found out the trees turned out fine anyway. Might have to do taht now though.

[thomthom]

Re: Transparency/clip map not affecting the backside of the material

hm.... maybe I misunderstood... transparency isn't affecting backfaces at all? does it turn out fully opaque?

[Free Agent_cg]

Re: Transparency/clip map not affecting the backside of the material

no it renders exactly what u see on the back face, which makes sense for anything that isnt clipmap cos u want that transparency to translate to the back face like it worked in the original vray release. very sad and have already posted this request at Sketchucation go add an extra vote (it doesnt seem to be getting too much attention).

[thomthom]

Re: Transparency/clip map not affecting the backside of the material

Done!
Really hope they can do this.

[dalomar_cg]

Re: Transparency/clip map not affecting the backside of the material

Fernando and I took a look at this on friday, and came to this conclusion...

SU chooses to deal with front faces and back faces differently. Therefore, you can have different uvs (ie mappings) on the front and the back. If you can see it in the SU viewport, then thats how it will be rendered.

The thing is that there are advantages and disadvantages to supporting this, however, the only reason why this is even a question is because SU chooses to work in this way. This is not a normal thing for a 3d app to do. I don't know of a platform that separates front faces and back faces in the way SU does.

I think its best that we support SU's way of doing things, because what you see in the viewport will be what you get in the rendering. It might be possible to add a tag onto a given material to "Read mapping from front faces", but that wouldn't be the default. As far as "it worked this way in the original release", there were a number of things that were done incorrectly and this was one of them.

[Free Agent_cg]

Re: Transparency/clip map not affecting the backside of the material

hi dolamar thanx for the reply, if you were to add the "clip through" tag (haha i named it :P but u can go with "Read mapping from front faces" if you like its ur program) would that be featured in 1.00.75??? its a very important feature IMO

[thomthom]

Re: Transparency/clip map not affecting the backside of the material

In terms of expected behaviour I expect V-Ray to render what SU displays.

It just so happens that the way the original release did countered for SU's backface texture bug when importing 3ds models.

But my vote is still that V-Ray remain doing it the way it does in SR1 and rather seek for a solution in getting the texture correct in SU. But and option in V-Ray to override this would be great.

SketchUp does some weird stuff when it comes to backfaces. If you have a face where you apply a transparent texture on the front it automatically mirrors on the back if the backface has the default material. If you stretch and distort the texture on the front it updates the back. But if you apply a backface material, and you break that link. After removing the backface material to default, SU doesn't reset the mapping co-ordinates. Not until you make a change to the front side again, then it synchronizes again.

[Free Agent_cg]

Re: Transparency/clip map not affecting the backside of the material

if u initially dump a material on a face and it mirrors to the back its just a display if u pipet the back face u'll see its still a default material