I am looking for a better solution to make light in Cycles only visible, once it passed through a transparent object.
Example which is actually pretty close but has a few flaws, see below
A doorframe seems to have an invisible lit room behind it.
- the cone in front of the door, so the light source needs to be a bit further back than the door itself
- the floor that is visible through the door should be lit too
what i did:
I created something like a corridor to block the light to the sides but still light the floor inside the doorframe. I took advantage of the isometric perspective to get away with a kind of wonky shape. The backside (opposite of the door) is just an emissive material.
The material for the corridor:
This method works, as long as there are no other light sources in the scene, which I need.
Problem: The corridor blocks the light from the right and casts a shadow.
No corridor this time, just a transparent door guiding the light.
Red is a transparent material, the yellowish meterial is my light source:
The problem is the missing cone in front of the door.
Any ideas on how I could improve my methods?