Black Glass

[Aflac]

Sorry for the essay, but this is a problem I really want to solve:

I have been using Skindigo for quite a while now and every so often when I make a window system with multiple sheets of glass and then render it, some of the sheets of glass render completely black. I have seen this topic a million times in the forums and I realize that it is caused by the normals being reversed, which is an easy fix. My issue is that often times this problem arises after I make a copy of a glass component in sketchup and then make it unique to give it a different shape. The normals are still facing the same way as the original component in sketchup, but the new copies render black. I wanted to find the root of this problem, so I made a separate sketchup file with one original glass component (which rendered normally) and one copy which was made unique (which rendered black), and then exported an IGS file. I did some experimenting with the IGS meshes file and finally seem to have found the source of the problem: for the mesh of the copied component, the first value in the <matrix> section of the IGS file was -1.0. When I deleted the - and changed it to 1.0 the glass rendered normally. Now I'm not familiar enough with the coding of IGS files to understand what that means, but it appears to control the direction of the normals. To me this appears to be a bug with skindigo, when a component containing glass is copied and made unique, skindigo changes this matrix value, even though the normals are not changed in sketchup. So is this a bug with skindigo, or is there something wrong with my modeling methods in sketchup?

[Pibuz]

You're doing right, it is actually a bug.
..kinda old bug, though: in the current version this has been fixed!
Are you running a non-updated SkIndigo and Indigo version?

[lycium]

Hi, there's a tutorial in the online manual about making physically correct glass; hope it helps: http://www.indigorenderer.com/documenta ... ling-glass