George Anderson of Eugene, Oregon, e-mailed a request to turn 3D polylines into 2D polylines. Several routines he downloaded from the Internet claimed to perform this function, but all failed to set the z coordinate to zero. This month's solution is PLINE-3D-2D.LSP. I sent it to George, and he reports that it works for him. I wrote the code using the version of AutoLISP that comes with AutoCAD 2004, but it should work with 2002 also.

HOW TO USE PLINE-3D-2D.LSP
Download the AutoLISP file from www.cadalyst.com (see box above) and save it in the AutoCAD support directory. From the AutoCAD Tools menu, choose Load Applications, or enter Appload at the AutoCAD Command prompt. In the Load/Unload Applications dialog box, select the PLINE-3D-2D.LSP file from the support directory where you installed it, click the Load button, and then click Close. After you load the program, AutoCAD prompts you to type PL32 to start.

After you enter PL32, AutoCAD prompts you to select 3D polylines, shown highlighted in figure 1. Press to complete your selection, at which time the routine converts the polylines to 2D (figure 2). Note that the 2D polylines retain their layer dependence.