zLineFromPoints

transforms the Hermitian matrix defining the line by the given Mobius transformation matrix

sets the given ucircle to the projection of the line to the Riemann sphere

the normalized direction vector of the line

the angle of the line with the real axis

make all objects iterable, returning "self" in the simplest instance

length of the iterable assocaited with the object

method that is called on change events, calling reoutines to find current position based on dependecies, current visibility status, etc.

each object has a 4x4 matrix associated with it, representing the object's axis of rotation and translation from the origin. Needed for the implementation of the Projection class. Set to the identity matrix by default.

test whether any Elements on which there is a dependency have become 'null', i.e. not calculatable - .e.g, imaginary when working within real space

check for change in visibiliy status and toggle visibility as necessary, reset change flag to 0 on effectuating change in visiblity

toggle the 'null' flag, indicating whether the current postion of the object's position is visible - e.g. is real when working in real space

set object and the objects dependant on it to 'null' when its position cannot be made visible- e.g. imaginary when working in real space.

method to be overridden for objects needing an supplementary initiliazation routine after the call to __init___

Routine to return Element to intial position. Default is to run update routine

method to be overridden to erase loci of objects that are traceable

method to be overridden to erase curves traced by point objects

send current position of line frame's axis and position based on the line's current defining Hermitian matrix

set position of line's lab, if any

for consistency in iterating Element's rendering objects, all elements rendering information is in a list called self.rend. In the case of zLines, it is a single element list containing a cvisual curve object

export the scene's lines to PovRay SDL