Environment Map won't render shadow cast by alpha texture

Hi all,

I’m using Blenders Environment Map function to create skyboxes for a game in Unity, but I’ve hit a snag. I’m using a texture with alpha channel to cast transparent shadows and they work perfectly when rendered using the regular camera, but these shadows won’t turn up in the environment map. I’m using Blender 2.70 and the internal renderer.

Is there some specific button to toggle or workaround, or is this function broken?

Ok, I admit there wasn’t much info to work with, as I was under some pressure to solve this asap, but I did some small tests this morning.

Spot - Ray Shadow
Result: Alpha texture correctly casts shadow in both render and environment map.
Spot - Buffer Shadow, Classical, Classic-Halfway, Irregular, Deep
Result: Alpha texture has no effect in either render or env map and only the full mesh casts shadow.

Sun - Ray Shadow
Result: Alpha texture has effect in render but no shadow is cast in env map, not even by the mesh itself.

So, my conclusion is that there is something technically broken or missing with the sun lamp. This means that the sun lamp can’t be used for lighting a scene when environment maps are important. I really don’t want to be forced to use a spot light as a sun, since the light rays are not parallel.

Any tips?