Glass Erases Texture Behind the Glass

[Stiglr]

Got this followup message from El Muttso via PM and he said it was OK to publicly post:

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Hi, about a week ago I was looking for a solution as to why my glass doors on my fire station were cutting out obj’s behind them, remember that?

Anyway, I figured out why and wanted to share that with you.

First of all, this is pertaining to X-Plane.

Now, for the meat and potatoes.
All glass objects must be separate from anything else, objects unto themselves.
All glass objects must be constructed as 1 sided.
All glass objects must be constructed of TWO identical panes placed very close together.
Normals need to be facing INWARD, towards the other pane.

In the hierarchy of the object, AC3D f8, I ungrouped everything so all I had to deal with were the four panes of glass. The inward looking panes listed at the head and outward looking at the tail.

Now, X-Plane it seems has a brain of its own and it decides, based on needs, what to paint. So to take control, open the .obj file in a text editor and place this bit of code in it.

ATTR_layer_group objects +1

The range is from +5 to -5 and it overrides X-Plane’s artificial intelligence as to what is drawn and when.
******************************************
This is what the tail of the file looks like:
IDX10 52 53 52 54 53 54 55 53 55 56
IDX10 53 56 57 53 57 58 53 58 59 53
IDX10 60 61 62 63 60 62 64 65 66 67
IDX 64
IDX 66
ATTR_layer_group objects +1
TRIS 0 132
******************************************
In WED, I grouped my fire station together, ie: glass, building and fire trucks, with the glass at the tail.

So, if you run across the problem somewhere, you now have the solution.