I'm trying to use a circle decal to mark the true center of a perfect square arena. No matter what I do, the decal won't change color. It just looks like a translucent wet spot in the middle of my floor. I want to make it red or yellow. Can it even change color?
Not possible. As nice as it would be, the decals remain a darker colour of whatever they're placed on.
As an alternative you could use an invisible light fixture, with a circle gobo projecting onto the center of your map. This would allow you to select a color