The objects in a BRL-CAD model are stored as Boolean combinations of primitive shapes and/or other combinations. These combinations are stored as Boolean trees, with each leaf of the tree including a corresponding transformation matrix. The arced command provides a means for directly editing these matrices. The first argument to the arced command must identify the combination and which member's matrix is to be edited. The comb/memb argument indicates that member memb of combination comb has the matrix to be edited. The remainder of the arcedcommand line consists of an animation command to be applied to that matrix. The available animation commands are:
Replace the members matrix with the given matrix.
Left multiply the members matrix with the given matrix.
Right multiply the members matrix with the given matrix.
Example 1. Rotate body/head 45 degrees about Z axis
mged> arced body/head matrix rot 0 0 45
Rotates member head (in combination body) about the z axis through a 45° angle. By default, the matrix commands expect a list of 16 matrix elements to define a matrix. The xlate option may be used along with three translation distances in the x, y, and z directions (in mm) as a shorthand notation for a matrix that is pure translation. Similarly, the rot option along with rotation angles (degrees) about the x, y, and z axes may be used as shorthand for a matrix that is pure rotation.
Reports of bugs or problems should be submitted via electronic
mail to <devs@brlcad.org>