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Problems rendering glass

Posted: Sat Aug 11, 2012 12:45 am
by eurikain
Hi everyone,
I created a simple model : three boards and some writing engraved in each board. I want the boards to have a glass texture.
Here is how I made the board :
- scaled a cube to get a board
- wrote over one board
- duplicated the board and the text two times so that I would have three boards
- modified and centered the text
- converted the text to meshes
- added a boolean modifier to each board using the text and set up on "difference"
- hid the text and disabled the render for the text meshes
- place the camera like I wanted
- selected the three boards and changed the material to the type of glass I wanted
- addd couple toruses under the boards to make sure that the glass material would work
- rendered and... here is the result :

So it seems that the glass material is only applied on the sides of the boards.

Any idea of what I did wrong or forgot to do?

Thanks in advance.

Posted: Sun Aug 12, 2012 1:21 am
by Hellfireboy
Okay, the problem is that there is no way to tell you what you're doing wrong if you don't tell us what you're doing in the first place. What are your material settings to create the glass. What are the world setting and how are you rendering; Blender Internal, Cycles, etc. ... 2744480034

Here is a very basic glass texture. The settings are as follows
Diffuse - 0, 0, 0
Specular - Intensity = 0
- Raytrace
- Alpha = 0.001
- Specular = 1
- IOR = 1.04
- Amount = 1
- Falloff = 1
- Depth = 5
- Reflectivity = .1

Ambient Occlusion
- Factor .75
- Multiply
- Aproximate
- Falloff = Strength .1

I also used an HDRI probe as a world texture with Influence set to Horizon =.25 and Mapping set to View to get a more interesting reflection. This is of course no where near the most advanced method of producing a believable glass material but just an example. At any rate if you still want to know what you're doing wrong fill us in on what you're doing.

Posted: Sun Aug 12, 2012 7:27 am
by eurikain
Hi, thansk so much for your reply. Sorry if I didn't give any of my parameters. I am kind of new to blender.
I tried your set-ups, but couldn't find the world set-ups (?). Didn't turn out good though...
I uploaded my blender file so that you can take a look at it :
I'm wondering if the problem doesn't come from my computer :/

Hope you can find what's wrong..

Posted: Mon Aug 13, 2012 6:04 am
by eurikain
I started a new file and recreated another design and tried to get a glass result and it works perfectly :) I don't know what happened in the other file, I guess I played too much with the parameters.

Thanks for your help your setups are perfect :) I found the world setup (it was pretty easy to find I don't know why I couldn't find it :/ ). I decreased the Glossy setup to 0.81 to have more of an "ice look".

Thanks so much!

Posted: Tue Aug 14, 2012 3:29 pm
by Hellfireboy
One thing that I noticed when looking at your file was that you had your diffuse type set to toon which would make it look a little odd since toon shaders have hard edges to make it look like painted cells. Another thing was your normals. When you used the boolean to etch in the letters it seems that all of the polygons on the letters themselves were facing the wrong way. To see your normal directions go to edit mode and open the properties list (press N) and go down to mesh display. There are two buttons there to display face normals and vertex normal along with a value for the length of the normal line to make them easier to see. To fix them go to the tool shelf (press T) and click "Recalculate" under normals.

On a side note, if you want to find more HDRIs, you can find them on Deviant Art by searching HDRI. There are a few made by zbyg that I've found really useful.

Posted: Tue Aug 14, 2012 8:15 pm
by eurikain
I don't really see what you are talking about... when i go to edit mode, the letters seem correctly shaped in the boards :/ Due to a small offset I had to manually move so verticles because the letters didn't look right in some spots though.

Posted: Fri Aug 17, 2012 3:40 pm
by Hellfireboy
Though it didn't seem to have a huge impact in this case, normals are something that you should be cognizant of for future modeling especially when you are trying to troubleshoot error in how your mesh appears to be reacting to light in a render. The normal is basically which side of the face of a polygon is seen as the front or the back and it is important to make sure that all of your normals are facing the same direction. To give you an idea of the importance of this try the following experiment. The detail of the instructions are really for those new to Blender who may be reading this.

1) Open Blender and delete the default cube
2) Press Shift + A and create a UV sphere
3) Press tab to switch to edit mode and Ctrl + Tab and switch to face select
4) Click on one of the faces and click "Flip Direction" under Normals in the toolshelf
5) Go back into object mode. At first you should not see anything wrong since by default Blender creates objects in Flat shading mode. Now change the shading mode to Smooth and see what happens.

As models become more complex the problem of normal facing can become more severe and if you start seeing strange artifacts like the one that will show up in the above demonstration this is how to fix them.