We are trying to accomplisch the effect of projected colours of stained glass.

I've tried to do it with a frame (casts shadow) with panels (not casting shadow), that have a transparency in the material. This works, but does not take the colour of the stained glass, only the colour of the light behind it.

I've also tried with a material that uses an alpha channel. This had the same effect.

The only way I could accompisch what we are after is by inserting a gobo with the desired colourshades on the wall.

Below you can see the look we are after (with the workaround):