what does heightmap background do?

it looks alot like heightmap, but it doesn't let me move the lightsource

I even tried changing it on the properties sheet instead of in code and it doesn't seem to do anything

Have you read this? It mentions the differences between bump maps and height maps.

thanks ashley,

but yes I read that. I see the differeence in bumpmap and heightmap

but there's a separate effect called 'heightmap background', and it looks like it has a fixed lightsource, but there is still a lightx and lighty to adjust. they just don't seem to do anything

Huh... I've no idea where that shader came from! Davo, did you write it and break the light?