CGTalk - Projecting textures through glass

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Mikeyboy

11-21-2004, 08:30 AM

Hi Dudes

I have to model a bottle for Smirnoff, got myself into this to force me to learn. And I'm coming up against little snags along the way. So far I have the glass bottle symmetrically perfect with the little embossments etc.

To stick the label on, I first made it up in Photoshop with an alpha channel, and then I connected it to a blinn shader as a projection making it transparent. Then I joined the glass shader and this label shader into a LAYERED shader so that one would be on top of the other, to give the impression that the label was stuck on. This all looks good except that the label is projected through mirrored on the other side of the bottle and you can see it because the bottle is made of glass.

Is there a way to set the depth that a projection travels, or a way to make it like a shadow where it stops at the first surface it hits.

(In case you're asking, I want it to be a projection because the bottle has an indented bump map area in which the label is to sit nicely and this is a projection, I want all the maps to have the same dimensions and 3D placement properties)

Thanks clever people

MikeyBoy

leigh

11-21-2004, 01:45 PM

You didn't say which application you're using, but it sounds like you're using Maya from your description.

In this case I would say the most direct approach would probably be to simply use a different placement method. Rather unwrap the model and place the label onto the correct area in the UV map, and then use that in your placement node. Now this may conflict with the placement you're using for your bump map - but perhaps you could still just line them up by trial and error? Alternatively, what method of placement are you using for the bump map? Probably a cylindrical method, yeah? If so, then why not use the same placement for the label? It sounds like you're currently using planar projection.

Mikeyboy

11-21-2004, 04:35 PM

Hey no way Leigh, I'm from the Eastern Cape (embarrassed to say what town).

Thanks for that, I was just checking if there was a way to set the depth of a projection but if there's not, I'll just set different placement node coordinates for the label and map it to the blinn in normal mode.
But this is what I don't get: the bump map for the smirnoff bottle is a cylindrical projection and it doesn't wrap around the bottle, it shows only on the desired side. I don't know how I did that, but obviously I can't do it again.

Thanks a lot!

Mike

leigh

11-21-2004, 07:21 PM

Eastern Cape, eh? :) I wouldn't have expected to find anyone out there doing any 3D, heh.

Unfortunately I don't have Maya here at home or I would check up on a possible solution for this... Maya may have a falloff option for changing the depth of the projection, but if it does, I don't know where you'd find the option (I'm certainly not an expert in Maya). As for the bump map... that sounds a little odd. Perhaps you didn't actually set it to wrap completely around the bottle?

At any rate, when dealing with objects like bottles and such, I've always preferred a UV approach myself. It just makes placement simpler :)

Mikeyboy

11-22-2004, 01:36 PM

Thanks Leigh, that's great. I've done that exact thing, mapped the label using UV, have better control and no wrapping. Stand by for my next snag.

(Nobody in EC does 3D, King William's Town no less, trust me. I've moved to a design house in Dublin and they have Diageo who own Smirnoff)

Mike

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