With Revolutions
If the value of Revolutions is not zero, then the Rotations will be applied in the initial X-Z plane as the geometry is revolved around the Z-axis.
For example, a square that is one inch on a side is rotated 90 degrees while being revolved 360 degrees around the Z-axis:
The rotation is computed about the centroid of the geometry. If a Centroid Offset is specifed, then the rotations will be computed about that point instead. The Centroid Offset is interpreted to mean a Z-distance parallel to the Z-axis.
For example, a one-inch square is rotated 360 degrees about a Centroid Offset of -2.0 inches while being revolved two full revolutions about the Z-axis:
With Extrusions
If the value of Revolutions is zero, then the Rotations will be applied about the centroid of the geometry in the X-Y plane as the shape is extruded.
For example, a one-inch square is extruded three inches while being rotated 90 degrees:
If a Centroid Offset is specified, it is interpreted as being a distance from the centroid of the geometry parallel to the Y-axis.
As an example, the same shape above with a Centroid Offset of 1 inch:
NOTE: Some models that were created with Spirix can be found at https://3dwarehouse.sketchup.com/user.html?id=1824658900641239202016828