PDA

View Full Version : Transparent film on shader: Like a very very thick coat of varnish?


howzit
11-25-2005, 10:33 AM
hi,
i am trying to make shader for a plastic product. It would have a very shiny, almost glassy smooth black plastic finish (like the sony PSP hand game). However, Im trying to get it to have a layer of transparent plastic over the black. So if i had something written on the black it would appear very normal until you tilted the product to an accute angle, at which point you would tell its being
a) very slightly distorted by the transparent layer, and
b), the shine would be apparent that its on a slightly higher surface/plane. To give you an idea, the starting point as an example would be a deep matalic Automotive paints, or the Nukei shader in Cinema. However, how can i boost or raise the hieght of the transparent film? Kinda like a very very very VERY thick coat of varnish, thats what Im trying to say

Distal
11-25-2005, 10:57 AM
hi,

i hope i understand well what u want to do
if yes, could u make a copy of your model, raise its size slightly, like x0.1 scale, then apply a transparent material (maybe a banji) only to this "envelope" ? u could then play with the refraction index to get what u want.

Erik Heyninck
11-25-2005, 11:14 AM
the amount of reflectance you want should depend on the viewing angle if i understand you well. in this case, use fresnel as it does just that.

AdamT
11-25-2005, 04:13 PM
hi,

i hope i understand well what u want to do
if yes, could u make a copy of your model, raise its size slightly, like x0.1 scale, then apply a transparent material (maybe a banji) only to this "envelope" ? u could then play with the refraction index to get what u want.
I agree. Give the plastic material/object a decent IOR (around 1.3-1.5) to create the effect.

flingster
11-25-2005, 04:17 PM
would fresnel in environment help? adam at least what he describes in based on angular viewing so surely fresnel would be needed.

howzit
11-25-2005, 07:43 PM
hi,

if yes, could u make a copy of your model, raise its size slightly, like x0.1 scale, then apply a transparent material (maybe a banji) only to this "envelope" ? u could then play with the refraction index to get what u want.

YES! this is what i want to do. I thought of this, but copying the model will instantly double the geomatry in the scene. If you look at automotive paints, they seem to have a layer of clear coat over the matalic paint. And you can see through to the base layer of the paint. Its just that i need this clear coat to be extremely thick.

hmm i quess i will have to scale up a copied the model and give it a transparent shader. But, would you be able to tell that its got a clear "skin" as opposed to a nice thick layer of varnish?
thanks

tcastudios
11-25-2005, 08:03 PM
Scaling the geometry (if it is not a sphere) will not work very good.Different parts will then be at different "depth" including negative (coat layer being under the baselayer)
Instead on the copy use "MoveNormals" ever so little. This way all polys will be at the same distance from the base.

Cheers
Lennart

howzit
11-26-2005, 11:05 AM
right on man, thanks for that tip hadent had thought of using the move normal command. I will be using your steady cam pro for this one by the way!! :thumbsup: :thumbsup:

basilisk
11-26-2005, 02:45 PM
You can also use the standard displacement channel to expand the geometry slightly (only needs a very small amount)

Papashango
11-26-2005, 04:47 PM
I would (as suggested above already) use a base material for the plastic look (some black material with wide glossy specular...), and add a second material that consists just of a color channel (white for example) and an alpha -> here you could use a Fusion shader that takes the BlackWhite Image of the Text and Multiplys a Fresnel above it, so the visibility depends on the camera angle... see screens for additional info (sorry that they are in german).

Hope it works,
papashango

http://www.geocities.com/jimifm/alpha.jpg
Alpha Channel of the Text: Fresnel w/ multiplied Fresnel above

http://www.geocities.com/jimifm/fresnel_alpha.gif

AdamT
11-26-2005, 04:49 PM
would fresnel in environment help? adam at least what he describes in based on angular viewing so surely fresnel would be needed.
Yep, I'd use fresnel in transparency and in the reflect channel. Well, I pretty much *always* use fresnel in reflection unless I'm doing a mirror texture.

AdamT [still pronouncing "fresnel" as "freznel" internally] :)

howzit
11-27-2005, 04:25 AM
use a base material for the plastic look (some black material with wide glossy specular...), and add a second material that consists just of a color channel (white for example) and an alpha -> here you could use a Fusion shader that takes the BlackWhite Image of the Text and Multiplys a Fresnel above it, so the visibility depends on the camera angle...
papashango

http://www.geocities.com/jimifm/alpha.jpg
Alpha Channel of the Text: Fresnel w/ multiplied Fresnel above



hi Papashango, thanks for that one, looks really interesting. I am not that advanced with textures for the moment, but I most definatley want to try and use this method. Could anyone help out by dumbing it down a little more, and the screen shot in English would really help me. Its one of those things I would like to try to understand, rather than just copy and do, then when the next hurdle comes along Im stuck.
"teach a man to fish and you have fed him for life".

By the way, what does that name "Papashango" mean? it sounds like something I have heard before, a very long time ago.........



.

Chrissyboy
11-27-2005, 12:30 PM
You can also use the standard displacement channel to expand the geometry slightly (only needs a very small amount)

Just been playing with this displacement idea, got this:

http://www.chriscousins.plus.com/files/shinyblack.jpg

I actually had to take the Index of Refraction for the outer object right down to 1.05, otherwise it was just 'refracting' the inner object entirely to its edge, so you lost the clear film effect. This meant I had to add some reflection manually, rather than rely on Fresnel in transparency to do it for me.

Scene is attached, if anyone's interested - you'll need to add your own HDR file in the shaders though. Cheers - Chris

dawsonbob
11-27-2005, 08:30 PM
Is the move normals command available in version 8.2? I'm doing a job right now where it would come in handy.

I'm doing a transparent poly (plastic) bag with a wrap around label. The bag contains the product (animal feed) that needs to show through in the transparent areas. Any ideas?

Thanks in advance,

Bob Dawson

Per-Anders
11-27-2005, 08:34 PM
move normals, rotate normals and scale normals are in 8.2 (they've been in there since 5 or 6 i believe or possibly even earlier)

dawsonbob
11-27-2005, 08:59 PM
move normals, rotate normals and scale normals are in 8.2 (they've been in there since 5 or 6 i believe or possibly even earlier)

Thanks, mdme_sadie.

I know this is another stupid question, but where do these commands live? This is one that I've never had reason to use before?

Thanks,

Bob Dawson

AdamT
11-27-2005, 09:34 PM
Their actually called Normal Move, Normal Scale, and Normal Rotate (not that you couldn't have figured that out), and they're located in the structure menu, and also in the R-click context menu. They only work in polygon mode, unfortunately.

dawsonbob
11-27-2005, 09:49 PM
Their actually called Normal Move, Normal Scale, and Normal Rotate (not that you couldn't have figured that out), and they're located in the structure menu, and also in the R-click context menu. They only work in polygon mode, unfortunately.

Thanks, Adam.

This is a perfect solution to my problem. I must have skipped over that in the manual, not knowing how valuable it was. This is not the first job where there's been a perfect solution that I wasn't aware of; I need to spend more time with the manual.

Thanks,

Bob Dawson

howzit
11-28-2005, 01:04 AM
I actually had to take the Index of Refraction for the outer object right down to 1.05, otherwise it was just 'refracting' the inner object entirely to its edge, so you lost the clear film effect. This meant I had to add some reflection manually, rather than rely on Fresnel in transparency to do it for me.

Scene is attached, if anyone's interested - you'll need to add your own HDR file in the shaders though. Cheers - Chris



HEY CHRIS, YES THIS IS COMING ALONG NICE NOW, THANKS FOR THE VISUAL TOO AND THE FILE!!
SORRY FOR THE CAPS FOLKS, RENDERING IN AFTER EFFECTS


.

CGTalk Moderation
11-28-2005, 01:04 AM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.