Shadow Mapping

OpenGL Shadow Mapping has been on my mind for a while now but I always put it to the back burner. With the recent changes to the 3D engine I thought what is a better time?



Here is a general look of the shadow mapping from a distance. It doesn't look THAT special here but it shows now that lights won't be able to go through solid objects. You could move something under that shaded area, put a new light and get some other shadow effects going.



The above screenshot shows that fine shadow detail is happening with the engine too.

It took over a days work to add the shadow mapping to a satisfactory level. It's surprising how finicky OpenGL is about such things. Apparently DirectX 10 and 11 have improved shadowing but I haven't really looked into that yet as RetroCopy prefers the multi-platform approach.

As to performance, I haven't measured multi light shadowing yet, but I still get over 60FPS with a single shadow being rendered into an offscreen 8192x8192 buffer. From my tests, even going as low as 512x512 is still acceptable from a quality point of view, though 2048x2048 is the nice balance in a large room. Seeing as the fillrate on my ATI 4870 allows at least 16- 2048x2048 shadows, I hope to get around 10 happening at 60+FPS. I'm probably going to allow the user to select which lights they want to cast shadows, at some point in time.

One thing that is a bit different about how I use shadow mapping is I am interested in making sure the light coming out of say an arcade machine is close to real life. So now I'll try to emulate that aspect.