8.2 Rotation

This record consists of four fields, of which the most common format is as follows:

XYZOrder<spc>Rot1<spc>Rot2<spc>Rot3<nl>

where XYZOrder is an integer indicating the XYZ rotation order (see below), and Rot1, Rot2 and Rot3 are all doubles identifying a rotation, in degrees, about a local axis; which axis is governed by XYZOrder. <spc> is the space character and <nl> is the newline sequence. Note that positive rotation values indicate counter-clockwise rotation, and negative values indicate clockwise rotation.

Note the term "local" when referring to the rotation about an axis; the rotation is dependent upon the current orientation of the cell. For example, if a cell's parent is rotated 90 degrees about the Z-axis, then the local X-axis of all child cells is aligned with the global Y-axis, and the local Y-axis of all child cells is aligned with the global negative X-axis. Note also that rotations are applied after any required translation, but before the scaling transformation, from the same geometry record.

XYZOrder has one of the following values, with the corresponding interpretation:

Value	X, Y, Z Order
0	X, then Y, then Z
1	X, then Z, then Y
2	Y, then X, then Z
3	Y, then Z, then X
4	Z, then X, then Y
5	Z, then Y, then X

For example, if the XYZ order is 3, then a rotation of Rot1 is applied to the Y-axis, Rot2 to the Z-axis and Rot3 to the X-axis. These rotations are applied in the order indicated, with the cell's local orientation changing with each.

If geometry data is not present, then the XYZ order defaults to 0 (X, then Y, then Z) and the rotations all default to 0.0 degrees.

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