Perpendicular Intersection Point

This construction generates a point that is the intersection point between a selected primitive (a line, arc, or circle) and the perpendicular from a specified point to the primitive. The perpendicular will always lie in the plane of the paper. If there is more than one possible constructed point, that nearest the specified point is generated (unless this is overruled by the presence of a qualifier.)

Examples

1. NEW STRA

   FPT X300 Y100

   TPT X300 Y100 PERP PREV STRA

   Here, the STRA has one endpoint defined explicitly and the other defined as the intersection of the perpendicular from the specified reference point to the previous STRA in list order. See Figure 20:16 below.

   

   Figure 20:16. Use of the PERPENDICULAR Construction

   Where the specified primitive is a line, the constructed point may lie beyond the ends of the line (as above).

   Other variations of the PERPENDICULAR Construction are shown below.

2. NEW STRA

   FPT X0 Y0

   TPT X0 Y0 PERP PREV CIRC QUAL @

   Here (see opposite), two constructed points are possible and so a qualifying cursor hit is used.

   

3. NEW STRA DEF X0 Y0 PERP @ X0 Y0

   Here (see below), the cursor hit selects the primitive and acts as a qualifier.

   

4. NEW STRA DEF @ @ PERP @

   In this case, the first cursor hit defines one endpoint of the STRA, the second defines one end of the line that intersects the circle, and the third picks the circle (and also acts as a qualifier). See below.