I want my (flying) character to fly into a tunnel and out the other end. Inside the tunnel I want it to be pretty dark so that the shiny collectibles are more punchy.
The directional light I am using for sunlight outside of the tunnel somehow penetrates into the tunnel mesh, causing walls to be lit as if there were holes in the tunnel mesh, which there aren't. Depending on culling settings, either one wall is lit or the other. When culling is disabled, there are still light leaks along the corners.
How do I completely shut off directional light from entering the tunnel? Can I disable the tunnel material from receiving directional light (but continue to receive other lights like spotlight)?
BTW, 'contact' settings alleviate the problem a touch but they kill the performance (which drops to 7fps with contact on)