Particle rotation


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

# rotation around Y axis by given angle

# rotation around Z axis by given 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.

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.

For the time being, particle rotations are carried out around the reference point in the center of the bottom of the particle. This shall be revised soon.

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