Shadow Volumes

OpenGL Development JOGL Development
#1

A quick peek at the Xith3D/jogl engine casting shadows. These models are not completely sealed, so the shadows are incorrect in some places.

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Question 1: Does anyone know a way to take a arbitrary shape and build a form fitting hull that is sealed? It would be nice to have the code create a good shadow occluder (and lower poly too) when the shape itself does not conform.

Question 2: Self shadowing mostly sucks in shadow volumes, especially if there are lots of detail. I would prefer to use vertex or pixel lighting for that. Anyone know a way to change the stencil algorithm to not draw on itself?

Dave

#2

I fixed some bugs in the shadow volume code. here is the result:

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Unfortunetly this is implementing the Zpass algorithm, which has a fatal flaw when the viewer enters the shadow.

The only solution I know is to change to a zfail algorithm and build back and front caps for the volumes, which I have not figured out how to do yet.

One thing is that the performance is really good so far since I only recalculate the geometry in the volume if the lightsource changes or the occluder moves. This scene is rendering at 200 fps.

#3

That’s almost frustratingly pretty. Now implement bumpmaps and projected lights, and you’ve got yourself a doom3 engine. :wink:

As for Question 1, I think I’ve read articles like that on either gamedev.net or gamasutra.
Actually, it was about retesselating a mesh into more uniform triangles or something, iirc. I wasn’t really paying attention. :wink: