> Consider how path-tracing works.  It's like adding diffuse reflection to all
> surfaces.  First, a ray is sent out at a given pixel.  When that ray hits
> something, it spawns more rays.  This happens recursively, and if one of the
> paths ends up at a light source, that color is transferred forward to the
> pixel.  If the light sources are too small, 99.999% of the rays are never going
> to find a light source.  The 0.001% that do find a gap in the door after a
> bounce or two result in the "stars."  However, if you use a portal, then you're
> saying that you know in advance where the light is, so we'll always send a ray
> in that direction, just in case.  Not perfect, but it makes a huge difference.

I didn't yet manage to put that to good use for my scene; all I got was a
tremendous slowdown per pass, less "stars", but also less visibility of the
door.

Then, Windows crashed again. Looks like it just needs its daily reboot.

I'd love to give it a try on Linux, but I can't seem to get MCPov compiled
properly: icrc gags on the source code, and gcc gives me an executable that
just segfaults. Using Debian "etch" 4.0r5 for AMD64.

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