Material Help: Glass w/ Normal on 1 Side

[kmwhitt]

I've got a display cabinet that has 2mm thick glass.  The client has requested restoration glass which has a raised pattern of what looks like scratches on the exterior face and smooth on the back.  When I apply my normal map with cubic mapping, this raised pattern is applied to both sides making it too busy and therefore, unrealistic.  If I assign a selection tag to the front plane of the glass only and assign the material with a normal to this selection only and a "normal-free" version of the glass to the rest, I appear to lose the refractive quality of the glass.  Is there a way to do this short of having to model the tiny pattern on the face of the glass?  The attached image shows the cubic mapping with normal on both sides (too busy and unrealistic).  I really need it on the outside face only while retaining the refractive quality of the glass.  Any ideas?  Thanks, Kevin

[BardhylM]

Maybe this solution would solve it for you.
You have to unwrap those glass object you need, and assign a different map channel if you need for other textures to have a box mapping.
The parts that have relief you make planar mapping or whatever and fill the UVW unwrap window with them.
Where as the other parts just scale them down to a point that the texture does not have effect on them.
It's a dirty solution but worth a try.

[Beanzvision]

Or you could try to enable "thin (no refraction)"?

[romullus]

@beanzvision, but you would loose refraction this way and OP's reference clearly shows refraction effect in play. I think that option with different material IDs, is the only correct one here. In 3ds max you don't even need to unwrap the object - simple box (cubic) mapping would be enough, but since this is for C4D, i can't comment on that.

[ficdogg]

have you tried using the displacer deformer with a restriction tag to just the front face?
That should give you polygon level deformation so that you can use just a regular glass material.

[kmwhitt]

Maybe this solution would solve it for you.
You have to unwrap those glass object you need, and assign a different map channel if you need for other textures to have a box mapping.
The parts that have relief you make planar mapping or whatever and fill the UVW unwrap window with them.
Where as the other parts just scale them down to a point that the texture does not have effect on them.
It's a dirty solution but worth a try.

BardhylM - thanks for the reply.  I don't follow you regarding the map channel.  Are you saying I should unwrap all of the glass surfaces and shrink those to not be effected by the normal map.  Or are you proposing multiple UV tags?  I didn't know you could use multiple UV's in C4D.  I'd appreciate a little more info.  Thanks again, Kevin

[kmwhitt]

have you tried using the displacer deformer with a restriction tag to just the front face?
That should give you polygon level deformation so that you can use just a regular glass material.

ficdogg - that's a good idea.  Thanks.  I have never used this deformer.  I imagine I'd have to have a black & white map to do so.  I am working with a normal map right now.  I'll give it a try.

[Cinemike]

When I need to mask sides out (and can't use poly selections for some reason), i like to use a vertex map as a mask.
I don't see much difference to using a poly selection here, though, nor was I missing the refraction.
Anyway, maybe this method could be of some use for you (replace the missing normal map with one of your choice in the file).

Top glass: normal on both sides, you are right, far too busy.
Left glass: the vertex map solution
Right glass: the selection set solution

PS
As the file name says, there will be another crash with IR I need to report ;)

CU
Michael

[kmwhitt]

have you tried using the displacer deformer with a restriction tag to just the front face?
That should give you polygon level deformation so that you can use just a regular glass material.

These are very fine hairline cracks (the map is 8k).  Isn't it necessary to subdivide the mesh to get the displacer to work?  If so, it would be too dense to use.

[BardhylM]

Maybe this solution would solve it for you.
You have to unwrap those glass object you need, and assign a different map channel if you need for other textures to have a box mapping.
The parts that have relief you make planar mapping or whatever and fill the UVW unwrap window with them.
Where as the other parts just scale them down to a point that the texture does not have effect on them.
It's a dirty solution but worth a try.

BardhylM - thanks for the reply.  I don't follow you regarding the map channel.  Are you saying I should unwrap all of the glass surfaces and shrink those to not be effected by the normal map.  Or are you proposing multiple UV tags?  I didn't know you could use multiple UV's in C4D.  I'd appreciate a little more info.  Thanks again, Kevin

Hey Kevin, no problem man. Just saw it and had the same problem a while back. I think that is what i used as a solution.
I'm a max user and didn't know C4D didn't have multiple map channels. But for this I think it wont matter much, because it's glass and the main polygons are the outer ones.
Yeah unwrap all the glass and leave a normal usable size only for outer polygons, others scale down. I used this method a while back because separating with Mat ID would get funky refractions.
It's probably fixed now, haven't checked.
Hope you find a solution, and have a nice day dude.

[kmwhitt]

When I need to mask sides out (and can't use poly selections for some reason), i like to use a vertex map as a mask.
I don't see much difference to using a poly selection here, though, nor was I missing the refraction.
Anyway, maybe this method could be of some use for you (replace the missing normal map with one of your choice in the file).

Top glass: normal on both sides, you are right, far too busy.
Left glass: the vertex map solution
Right glass: the selection set solution

PS
As the file name says, there will be another crash with IR I need to report ;)

CU
Michael

Thanks Michael.  Maybe the missing refraction is just my imagination...  I appreciate the tests you ran.  I'll try the vertex map trick as well.  Kevin

[kmwhitt]

Maybe this solution would solve it for you.
You have to unwrap those glass object you need, and assign a different map channel if you need for other textures to have a box mapping.
The parts that have relief you make planar mapping or whatever and fill the UVW unwrap window with them.
Where as the other parts just scale them down to a point that the texture does not have effect on them.
It's a dirty solution but worth a try.

BardhylM - thanks for the reply.  I don't follow you regarding the map channel.  Are you saying I should unwrap all of the glass surfaces and shrink those to not be effected by the normal map.  Or are you proposing multiple UV tags?  I didn't know you could use multiple UV's in C4D.  I'd appreciate a little more info.  Thanks again, Kevin

Hey Kevin, no problem man. Just saw it and had the same problem a while back. I think that is what i used as a solution.
I'm a max user and didn't know C4D didn't have multiple map channels. But for this I think it wont matter much, because it's glass and the main polygons are the outer ones.
Yeah unwrap all the glass and leave a normal usable size only for outer polygons, others scale down. I used this method a while back because separating with Mat ID would get funky refractions.
It's probably fixed now, haven't checked.
Hope you find a solution, and have a nice day dude.

Thanks again!  You're solution is working just fine.  Kevin