Is there anything implemented that allows this to happen? I have some HDRI of umbrellas etc that I want to use, but don’t want to see the black around the image blocking out the scene behind the umbrella. I tried messing with the alpha mapping under Extra Attributes, but didn’t have luck with it.
Any way to have alpha/opacity mapped RectLights?
From what I remember, you need to change the alpha of the bitmap assigned to the rectangle map.
Best regards,
Vlado
Ah okay I see, so if I pump an alpha map into my RectLight map’s alpha gain channel, that will function the way I’m expecting?
I’ll give it a shot, thanks Vlado.
It depends on what you are expecting 
It will make the light transparent, yes. But the alpha will not affect the way light is emitted (i.e. the alpha will not multiply the emission color).
Best regards,
Vlado