I see a lot of skills in the games I play where they have a skill or a search area that projects a drawing on to a map, like a circle or something similar and I have no idea how that is done, and I don't think they use a texture to draw it. For the projection, I think, they use some kind of ray-cast to find the shape of the map and then go from there but I may be far off from truth.
In the linked image example you can see the circle is projected on the flat surface and the stairs. (And how is that glow effect around the circle achieved or is that part of a texture?)
Can someone tell me how is that done or point me to the right direction?