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How do I make a transparent plastic object look transparent?

ZBrush Artworks
#1

I am trying out the demo for ZBrush, and have tried to accomplish this with no real success. I need to be able to draw an object such as a cup, and to be able to make it appear to be composed of semi-transparent plastic. The real trick here, is that I need the edges behind the front of the object to be visible THROUGH the object, as any TRUE transparency would provide. With ZBrush, it seems that the only thing that is visible through the transparent object, are OTHER objects behind the transparent one.

Any help would be greatly appreciated. :slight_smile:

#2

Hi mikepbm
What you need is something like this?

I made a quick minitut of this
transparency glass plastic.TXT
please let me know if this work for you.
Thanks for your attention
Andreseloy

#3

since I read your post upond waking up I began to try to accomplish your task…here is the result and a script that I havent tested yet showing how I got to this…I use the jelly bean material with my transparencies…

eggsTransparent1.TXT
The thing if you don’t realize yet is to work in layers, and baking the layer after doing best renders to work with the different materials with various objects and lights…I hopes this isn’t too vague and is of some help to you. One of the better artists around might have better insight into what you are wanting if I was wrong in what I have shown. Happy Zbrushing :+1:

EDIT…Andre was all over that question and beat me to the punch…Great job Andre :+1: :+1:

Kewl beans guys…I edited out the image…as to not take up the thumbnails…good luck on your project gentlemen.

#4

Thanks for your quick response. Andre, your object is very similar to what we are trying to achieve.

There is one small difference, and it is the key to the results I am trying to achieve. When working with a solid object, there are inherent “hidden” lines that are only visible through the 3D object when viewed in a “wireframe” or “mesh” view. But when the object is rendered, those “hidden” lines are not visible. They should be when the object is transparent. There doesn’t seem to be a way to achieve that with ZBrush. In other words, I need to be able to see the other corner of a cube, THROUGH the cube. Without drawing anything more than one object.

I hope that is more specific.

Thanks

#5

Another approach is to use one layer, and to split your transparent object in half.

First, draw the background. Bake the layer.

Next, draw the half object rotated so that it is facing away from you. Reduce the RGB Intensity and activate Draw>Refraction. When satisfied, snapshot the object.

Now you can draw anything that will be inside the object.

Bake the layer.

Lastly, draw the half object again, rotated so that it is now in front of everything else (facing you). Tweak the RGB Intensity and Refraction settings if you want. Snapshot the object.

You will now be able to see the back of the object refracted through the front of the object. Anything that is inside the object will also be refracted, and the background will be refracted through everything.

#6

Hi Mike,

I see your problem, the interior rear edge of the cup doesn’t render.

I tried a test that “sorta” does what you want, by copying the original object, in this case a cylinder, and reversing the normals: Tools\modifiers\flip, then scaling it down slightly and rendering. While experimenting with each element on a different layer, I got all kinds of odd renderings and orders of transparencies, so try different rendering with each layer selected (turn Render\Flatten Layers off).

Sorry, I don’t know enough about configuring ZBrush to control the rendering yet but I’m learning!

Good luck. I hope ZBrush does it for you. Sven

#7

The issue (just so mikepbm understands what is happening here) is that once you drop an object on the canvas, it ceases to be a 3D object and becomes Pixols. On any given layer, there is only one Pixol for each pixel in the image–i.e. you can’t have Pixols behind other Pixols without using multiple layers. If you drop a sphere on the canvas, it becomes a hemisphere. It still looks like a sphere because the half that you lose is facing directly away from you. But in reality, the only parts of objects that exist are the parts you can see.

The best way to understand Pixols is to imagine one of those flat little toys with all the metal pins in it–you know, the one where you press your hand against the back and it raises the pins up on the front in the shape of your hand. Those pins are a lot like Pixols. When you drop an object on the canvas, it’s locking the pins in place and taking away your hand. You still have the impression of your hand, but only the parts of the surface that were facing the pins. The back side of your hand no longer exists, as far as ZBrush is concerned.

#8

Aurick:
Question regarding the process you suggest here. Do you render the layers before you bake it? I ask because it is my understanding that if you bake a layer then lighting does not affect that layer at all. So if you want specific lighting on your object you wouldn’t get it if the layer is already baked. :qu:

#9

Aurick:
Another question. How do you split the object in half? I can’t seem to figure out how to do that! I have done one here but with the whole object so it didn’t turn out right. Please tell me what I did wrong! Thanks as I would really like to get this one, I could use it for sure.

:large_orange_diamond: :large_orange_diamond: :large_orange_diamond:

#10

I have similar problem, im not sure if i understand the Aurick suggestion in right manner.
This is an example

Aurick is possible a zscript related your topic?
Thanks very much.

#11

thats one :cool: approach, Matthew! i gave the technique - as i understood it - a try and it basically did what is expected, but i have had trouble to cut it in half properly + i need to do lots of research re: refraction to make it look like it should. i attach a script with recorded session (sorry, demo-users, i created a polymesh pretty soon, so it wont run in demo-mode :frowning: ), mayhaps you find the time to have a look and to tell me what could be done to improve the effect - and how to get rid of the seams when adding the front part :slight_smile: thanks in advance and thank you, mike, for bringing this up!

  • juandel
#12

Why not just make the glass (or import it) so it has an inner and outer face ?

glass.zip

#13

Ah ! I see now - you want the glass to be seen through the glass not just the inside ? So in this shot we should be able to see the bottom of the glass ?

#14

To cut it in half, I mask one half of the object and then use Tool>Modifiers>Selection>Hide Points. I then unmask it again.

Regarding baking, yes – you should do a best render before baking so that you get shadows and such as you want them. You may also have to fake some shadows after you’re done by painting them yourself.

#15

Aurick:
Sorry to be a pain but I have run into another problem I have never been able to get past. And that is Masking! I have watched all the tutorials I can find on maskiing and none of them have been too helpful. You say you used a mask to cut your object. If you have a zscript to show how you did this I would be eternally grateful! I tried but I ended up with all kinds of creations with ragged edges, masks that didn’t fit the object, you name it I got it, everything except a clean half an object!
Thanks so much.

#16

Heres a quick plastic cup I did with a different method… Although its using more than one object… With some more tweaking, it could probably be made to look realistic… First I placed the background… Then created a new layer and using the SweepProfile3D made the body of the cup… Then I made another layer and using a Cylinder3D, I adjusted the Z axis and the TaperTop sliders to make the bottom of the cup… Using another Cylinder3D I made the water level… Maybe this will give you some more ideas.

#17

This is a very original to me Nocturnal Congraulations, i will make something with this approach¡¡ also to Juandel for the script I will do exercise with it and try to do some work.
Congratulations
PS: Nocturnal451 please can you make a zscript about your technique? I was trying but I think im missing some important step¡
Thanks for your time

#18

I’ve been playing with this today and learnt a lot about zbrush (never bothered with layers before…) :slight_smile:

and a recorded session:-

(edit) try again :slight_smile:

alantry4.zip

#19

Northstar - I hope that I an not “teaching my granny to suck eggs” but I found out today that when masking (ie ctrl and draw) if you choose tranform palette/move and a square alpha then ctrl drag will select an area with a flat edge. Hope this helps ?

(edit)
ctrlmask.zip

#20

Well thanks for the suggestion, at this point I am willing to try anything. But it didn’t help. I still got the same ragged results I have always gotten when I try to mask. Take a look and you will see what I mean. I have tried increasing the density of the mesh, doesn’t help. I really would like to know what I am doing wrong, or what I am missing.

This is getting embarassing, and I am getting desperate. Until I can master this masking thing, it is of no use to me at all! It is the one area that I don’t seem to get at all for some reason.
Still open to any and all suggestions.
Thanks