there is no reason why there should be a four light limit in most cases, when baking mixed lights with shadowmask. you don’t need to generate an occlusion map for lights that can’t possibly reach the object (ie for lights that are on opposite sides of a wall)
yet when splitting the scene into two, and loading them both additively, you are able to have 6 lights with shadowmasks that are in range of one another, though it is very cumbersome. just bake all shadow maps and discard fully black results
The reason for the 4 overlapping lights limit is that the shadow mask texture has four color channels. The light overlap calculations are done without taking occluding geometry into account.
is it possible to take occluding geometry into account, or not include the 5th light in the overlapping region specifically, or split each float color channel into two 16 bit half type, or to produce multiple textures, or is it not feasible? is there anything like this in the works?
it would make a big difference, to my game specifically at least