All posts related to V2
By bjorn.syse
#315690
Hi,

How can I put a decal on a revolved glass surface?

I've made a 2-layer material with an opacity mask, which works fine in itself. One glass layer, and one paper layer above with an opacity mask and a texture on reflectance 0-channel.

1. If I use a planar or "divided box project", I end up having the decal repeated on the inside of the glass surface, and on the backside. If this would have been a non-transparent object, that would have been fine. But it isn't.
Image

2. If I try to split the front surface, and make two different materials - one glass material without the decal, and on with the decal. And then only use the material with the decal on the front side,. this does not make the glass material behave anymore. Perhaps because it is not a solid object anymore.
Image

Anyone got a clue for a different approach? ...or will I not be able to use a decal with opacity masking on a transparent object?

Best regards,

- Björn
User avatar
By Maximus3D
#315696
Depending on the application you use there are different ways to do this..
I would do it by making a selectionset of a group of polygons on the bottle where the label(s) should be.
Then assign my labelmaterials to those selection(s) and then render.
I'm sure someone else can come up with a better method to resolve this.

/ Max
User avatar
By oz42
#315702
Or you could do what happens in reality :wink: (have a bottle and separate label)

- have a bottle object with just glass
- duplicate this geometry (just the cylindrical part, not the neck or base)
- 'push' the normals of this duplicate object a fraction of a mm outwards
- place a label material onto this new geometry with a clipmap

I use this method and it works fine, you end up with two objects with separate materials but this is how it's done in the real world :D
By bjorn.syse
#315703
oz42 wrote:Or you could do what happens in reality :wink: (have a bottle and separate label)
i know, :D I actually ended up doing it like that,. but I just wanted to know if someone had a different way of doing it..

I hate how things are done in reality! :shock:
User avatar
By Michael Betke
#315715
A UV set is a simple multi-mat material.
If a face got the id=1 it uses a material without the label. If you apply id=2 it uses the other one.
Its really simple. I'm using 3dmax so I don't know how this is done in Rhino. But at least you keep your closed mesh. It's a clean way.

Pushing the label faces a little bit outwards is also a quick way.
By bjorn.syse
#315716
thanks, But I'm pretty sure these terms don't really apply to NURBS in rhino.. They sound like polygon terms. In rhino, I'm forced to use something called "Texture projections".
By Polyxo
#315727
Hi Björn,
it should be pretty simple with a single surface for the label which floats with a tiny offset
in front of your bottle. If you want the back side of the label unprinted just use two surfaces
and make the backfacing one grey or add the stripes of glue :D .
Maybe Jeremy knows another trick but I don't recall a way to make a normal Mxm single-sided inside Rhino.

Holger
By JDHill
#315735
There is a way to do this in Rhino, but you have to use Mesh > From NURBS Object. First, make your texture map so that it can be cylindrically applied, i.e. the decal will be off to the left or right of the image plane. Then:

1. make your glass material
2. revolve your bottle profile
3. assign the material
4. extract the bottle's inner shell
5. set the outer shell to use cylindrical mapping
6. set the inner shell to use planar mapping (projected from above)
7. stretch the planar mapping such that the decal portion falls outside the object
8. use Mesh > From NURBS Object to make two meshes
9. hide or delete the NURBS bottle
10. run Join on the two meshes

Now you should have a single mesh with your glass material applied, where the decal is only visible on the outer surface, as you have cylindrically projected it in step 6:

Image
User avatar
By caryjames
#315749
Hey JD- I like the step by step process but I am missing something here. Could you explain some of the reasons behind the steps? I know that this is a BIG request and I am sorry to be a pain but I just don't get it... if I had to model and render this bottle and label I would have modeled them as separate objects and then rendered from there. Thanks in advance for your reply as usual :).

Cary
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