Provides similar functionality to that of the nentsel function without the need for user input
(nentselp [msg] [pt])
A string to be displayed as a prompt. If the msg argument is omitted, the Select object prompt is issued.
A selection point. This allows object selection without user input.
nentselp function returns a 4W4 transformation matrix, defined as follows:The
The first three columns of the matrix specify scaling and rotation. The fourth column is a translation vector.
The functions that use a matrix of this type treat a point as a column vector of dimension 4. The point is expressed in homogeneous coordinates, where the fourth element of the point vector is a scale factor that is normally set to 1.0. The final row of the matrix, the vector [M30M31M32M33], has the nominal value of [0 0 0 1]; it is currently ignored by the functions that use this matrix format. In this convention, applying a transformation to a point is a matrix multiplication that appears as follows:
This multiplication gives us the individual coordinates of the point as follows:
As these equations show, the scale factor and the last row of the matrix have no effect and are ignored.