sweethome3d_window_pane is just a way to set a shape as transparent. It was introduced in an old version of Sweet Home 3D before the MTL file and d parameter were supported. In the current version, its main drawback compared to d parameter in a MTL file is that it's fixed to 0.5 and that you can't change its appearance in the furniture Furniture materials dialog box. When changing individual materials wasn't available, it was handy because when you changed the color of the window, only its frame was changed and the pane remained uncolored. But in version 4.3, changing the material of a window pane won't have any effect, something that looks more buggy because it's not necessary for backward compatibility. I just fixed it in the Beta 15 of the version 4.4.
I am wondering whether sweethome3d_window_mirror_xxx (reflection) can also be achieved with .mtl.
It seems that "illum 3" in MTL file format could match the mirror effect, but I didn't investigate further when I programed the first mirror effect. The good thing with introducing special names for shapes, is that it can be easily supported in file formats afterwards.Conclusion: pencilart, using d parameter works, but mixing it with sweethome3d_window_pane name won't change transparency value. Hum, maybe I should fix that too!
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Emmanuel Puybaret, Sweet Home 3D creator
