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Particle rotation

Constructors

Rotations are created by the following constructors:

# Euler z-x-z sequence of rotations
RotationEuler(alpha, beta, gamma)

# rotation around X axis by given angle
RotationX(angle)

# rotation around Y axis by given angle
RotationY(angle)

# rotation around Z axis by given angle
RotationZ(angle)

Angle arguments are understood in radians. Use *deg to convert from degrees.

The Euler angles alpha, beta, gamma refer to the z-x'-z'' convention:

  • The object is first rotated by alpha about the z axis. The coordinate axes, rotated along with the object, shall be denoted by a prime: z'=z, while x',y' differ from x,y.
  • The second rotation is by beta about the x' axis. The coordinate axes, rotated along, are now denoted by a double prime.
  • The third rotation is by gamma about the z'' axis.
Usage

Rotations can be applied to particles and to inter-particle structures.

Initial orientations are specified by the drawings in the form factors and inter-particle structures documentation.

Particle rotations are carried out around the particle reference point, which for most shapes lies in the center of the particle bottom. Rotations leave the particle position unchanged; hence rotations and translations can be applied in any order.

Rotations affect only rotated objects, not the coordinate system. Therefore subsequent rotations are carried out with respect to the original coordinate system.

Examples