Saint Gorbain Glass library errors

ararch · Post by **ararch** » Mon Oct 22, 2012 8:43 pm

Dear users,

I accidentally stumbled on a problem while rendering glass material with SU and INDIGO 3.2.13.
The glass material imported from the library didn't turn out to be transparent. It was solid. So I run some tests with the glass material and came to the conclusion there are some specific regulations how to apply the glass material to a certain object.

First I made a matrix with objects (see picture).
In the first column the material glass in the library is Linked. The object is push-pulled for 20 mm.
In the second column the material glass in the library is imported. The object is push-pulled for 20 mm
In the third column the material glass in the library is Linked. The object is push-pulled for 20 mm using +
In the fourth column the material glass in the library is imported. The object is push-pulled for 20 mm using +

The first row the glass object is drawn from the left upper corner to the right downside corner.
The second row the glass object is drawn from the left upper corner to the right downside corner and made as a group
The third row the glass object is drawn from right under corner to the upper left.
The fourth row the glass object is drawn from right under corner to the upper left and made as a group.

By implicating the material, different results appeared. The second column doesn't seem to have any problems so my conclusion will be:
Always import materials in SU instead of linking and don't use objects witch are push-pulled with using the + (control key in push pulling).

Hope this error will be fixed in later versions. Just want to share my observations with you.

Headroom · Post by **Headroom** » Mon Oct 22, 2012 10:14 pm

Usually when something turns black like this, the problem is that the surface normals don not point into the correct ( outward) direction

Zom-B · Post by **Zom-B** » Mon Oct 22, 2012 10:34 pm

ararch wrote:The glass material imported from the library didn't turn out to be transparent. It was solid.

There is a good chance that this is because of some special code parameter in that glass materials called <private_data> as you can see here.
to read that encrypted data isn't supported by most (!?) exporters atm (since quite nobody even know it was there!).
Saint Gorbain Glass will keep their data save and still allow you to use it, so that measures is very reasonable!

Atm you only can load that material into Indigo GUI during rendering and apply to the window by hand!

(btw. take care to aply your material correctly to the glass: http://www.indigorenderer.com/forum/vie ... 10#p113610)

ararch · Post by **ararch** » Tue Oct 23, 2012 12:59 am

Thank you headroom. I already had a headache about it. Thanks for the explanation,
And Thanks Zom-B for the link. That reveals a lot. Also I 'm going to imply the material the wright way according to the link you send me.
Thanks again.

galinette · Post by **galinette** » Thu Oct 25, 2012 11:44 pm

Zom-B wrote:There is a good chance that this is because of some special code parameter in that glass materials called <private_data> as you can see here.

No, these materials follow the same use rules as specular materials, and will turn black in the same cases (normal issues or non-closed medium volume).

The tricky part is to use it as recommended, ie with different materials closing the glass volume, each sharing the same medium. But this info (medium object and medium name in specular material object) is not encrypted and follows the same rules as specular materials.