2010-09-10, 11:44 AM
I was trying to think how a penumbra could be worked into the shadow sets, and I'd given up on the idea more or less, but the solution was so obvious. If the light indices are signed values. Essentially you can use the absolute value to knockout the lights then mask that vector in such a way to get the affected index, and if it's negative say the vertex is inside the penumbra, and if it's positive it's inside the umbra (https://en.wikipedia.org/wiki/Penumbra)
So in other words every vertex that is part of the map can be in the shadow of up to four lights and can either be in the umbra or penumbra of each of those lights. In the umbra no light gets thru, and the penumbra is about half light. Any smoothing of the shadow would be due to blending between vertices. Penumbras especially happen (around lightbulbs anyway) when something is close to the light source that casts a sharp shadow across a large space, but the penumbra could also be used as a tweaking factor for softer outdoor type shadows when desired, and artificially smoothing out the edge of the shadow across adjoining vertices.
This will be the basis of my "Dark Slayer" map editor I think. I can't come up with anything better / more appropriate. It's seems like a logical progression of Som's lighting and doesn't suggest anything messy like shadow mapping or require anything much more than Som already provides.
So in other words every vertex that is part of the map can be in the shadow of up to four lights and can either be in the umbra or penumbra of each of those lights. In the umbra no light gets thru, and the penumbra is about half light. Any smoothing of the shadow would be due to blending between vertices. Penumbras especially happen (around lightbulbs anyway) when something is close to the light source that casts a sharp shadow across a large space, but the penumbra could also be used as a tweaking factor for softer outdoor type shadows when desired, and artificially smoothing out the edge of the shadow across adjoining vertices.
This will be the basis of my "Dark Slayer" map editor I think. I can't come up with anything better / more appropriate. It's seems like a logical progression of Som's lighting and doesn't suggest anything messy like shadow mapping or require anything much more than Som already provides.