Where is exit portal most effective position?

[Meelis]

Where is exit portal most effective position?

Is it inside roome or outside roome, on glass volume surface.
Or must there be space between exit portal and glass sheet volume.

Why bidir is not working when exit portal is outside of room normal facing inside room and camera is inside room (on drawing)?

I used stained glass by galinette http://www.indigorenderer.com/materials/materials/688



MLT / path (bidir not working), light source only HDR map.

[CTZn]

Hi Meelis

In the first place, Galinette's stained glass is using a medium with ior, in other words it is meant to be applied directly to the glass volume, without intermediate surfaces. Doing otherwise will forcibly lead to a performance decrease, if not to a wrong result (specular isn't meant to work on single planes).

Regarding the exit portal question, think of them as light sources. They should in all cases be the first geometries to be hit by the environment light. Therefore their best position should be in the outside, further by (more than) the nudge distance from any other geometry. In your schematic the exit portal seems to be coplanar with the stained surface, wich is introducing an ambiguity that will produce unwanted results (ie: defeating bidir ?).

[Meelis]

Thank you CTZn

How should the UV mapping be done in blender or in general for the Galinette's stained glass on solid glass sheet?

Also with shaders, is there program that can convert it to texture or curves or 3d geometry inside 3d file that u can edit in Blender?

[CTZn]

How should the UV mapping be done in blender or in general for the Galinette's stained glass on solid glass sheet?

In general, a planar projection should be enough for a glass pane, box projection if you need the borders to be visible but they will match only on contiguous UVs.

Also with shaders, is there program that can convert it to texture or curves or 3d geometry inside 3d file that u can edit in Blender?

None that I know. On a theorical ground the ISL code could be converted into another shading language with some knowledge.