mat_scale_about_pnt "x y z" scaleMAT_SCALE_ABOUT_PNT(nged)
NAME
mat_scale_about_pnt - generate a uniform scale matrix centered on a point
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SYNOPSIS
DESCRIPTION
The mat_scale_about_pnt command generates a 4x4 homogeneous transformation matrix that performs a uniform scale by scale centered on the 3D point "x y z". Scaling about a non-origin point is equivalent to translating to the origin, scaling, then translating back; this command computes that combined matrix in one step.
The result is returned as a 16-element space-separated matrix string via bn_encode_mat. It is the GED wrapper for bn_mat_scale_about_pnt.
Arguments:
-
"x y z" : The center point for the scaling operation, as a space-separated string decoded by
bn_decode_vect. -
scale : The uniform scale factor (a floating-point number).
EXAMPLES
Example 1. Scale by 2x about a specific point
mged> mat_scale_about_pnt "10 10 0" 2.0
Returns a 4x4 matrix that scales geometry by a factor of 2 relative to the point (10, 10, 0). Objects at that point remain fixed while all other geometry moves away from it proportionally.
Example 2. Scale down by half about the origin
mged> mat_scale_about_pnt "0 0 0" 0.5
Returns a uniform 0.5x scale matrix centered at the origin, equivalent to a standard scale-by-half transformation.
AUTHOR
BRL-CAD Team
BUG REPORTS
Reports of bugs or problems should be submitted via electronic mail to devs@brlcad.org