CompuServe Messages

Patrick: What many drawing programs do is draw a filled arc at the end of the line. The arc belongs to a circle whose center is "after the end of" your line. For example, when drawing line AB below, the arc belongs to a circle centered on C: A————-B C The arc is filled, and runs from angle 140 to 210 (with zero to the right, increasing counterclockwise). So it looks something like this: D x A—————-BxxxxxC x E The arc is centered on "C", and is swept from "D" to "E". And it's filled as it is swept from CD through CB to CE. See? However, for large arrowheads it becomes obvious that this is an arc, and it doesn't look as nice. To do it "right", yes you will have to calculate the coordinates of points C,D, and E. But it's not hard, and it doesn't involve any trig functions. Calculate the slope of the line AB; the slope of DE is -1/m, where m is the slope of AB. Then you can use point-slope formula to find the coordinates of D and E. Consult your local high-school analytical geometry text….. -Peter