Shadows
polycounter lvl 20
I hope I am descriibing this right, but here it goes.
Say I have an object casting an ambient shadow. (A giant rock casting a shadow from the sun). The shadow of the rock is rather soft and thsu not as dark as it might be if it were a small object.
I place a smaller object in that soft shadow, and it is casting its own shadow from another source (point/spot/ambient, etc.). I don't just mean its casting an ambient occlusion shadow within the ambient shadow of the large rock, but rather a directional shadow. Since that smaller objects shadow is overlapping the larger rocks ambient shadow, its much darker on that overlap.
A.) Am I out to lunch here? I swear this is a.) possible and b.) done in a game before
B.) What is that called specifically?
Sorry for the lame description and no images.
Say I have an object casting an ambient shadow. (A giant rock casting a shadow from the sun). The shadow of the rock is rather soft and thsu not as dark as it might be if it were a small object.
I place a smaller object in that soft shadow, and it is casting its own shadow from another source (point/spot/ambient, etc.). I don't just mean its casting an ambient occlusion shadow within the ambient shadow of the large rock, but rather a directional shadow. Since that smaller objects shadow is overlapping the larger rocks ambient shadow, its much darker on that overlap.
A.) Am I out to lunch here? I swear this is a.) possible and b.) done in a game before
B.) What is that called specifically?
Sorry for the lame description and no images.
Replies
The quickest solution I can think of is to (if I got this right) tell the small rock to simply not cast any shadow, but instead to simply receive and generate AO around it.
Real-time soft shadow mapping by backprojection
Robust Stenciled Shadow Volumes
Dynamic Shadow Map Allocation
Umbra, Penumbra, and Antumbra
At least thats what it would be called in real life. Unsure if there is a specific rendering/game engine term for it.
They're called the same at least with soft shadows, but I'm not sure if the same terms apply in the case Adam described. As I understood it, the set up is analogous to such that you have object A lit by, say, a green spotlight and object B, nearby to A lit by a red spotlight from distinctly different angle so that the shadows of the objects overlap, and the end result is that A casts a red shadow, B green one, and at where the two overlap, the shadow is black, not receiving any light from either spotlight.
When you have for example separate shadow maps for the two lights, and assuming lighting and shadows of your renderer work as they should, you don't really need any trickery or smoke and mirrors to have such scene work as it should.