Determining The 3D Placement
When using a sphere map, or cube map within Maya you can place
and scale the projection using a 3D texture placement node.
In an API such as openGL you can re-create this using the texture
matrix stack. As far as extracting the data goes, you can start
by just treating it as a transform node.
We will also need to find the texture placement node which should
be connected to the "placementMatrix" attribute.