Sky Shaders: Where does LIGHTX_DIRECTION.z map to?

4.2.1

Question

I’m working on a sky shader and I wish to have the light rise/set in the east/west. I think that LIGHTX_DIRECTION.y maps to rotation.x and LIGHTX_DIRECTION.x maps to rotation.y. Is this a correct conclusion?

If so where does ‘rotation.z’ map to? I find that changing the value has no effect on LIGHTX_DIRECTION.z.

The source code in servers/rendering/rendering_rd/sky.cpp:1066-1068 seems to get the z coord of each of the basis vectors but changing those values directly doesn’t seem to be a direct mapping.

I know that there something I don’t understand here and would be grateful for feedback.