BBS: Inland Empire Archive Date: 06-25-92 (07:22) Number: 1336 From: FRANCOIS ROY Refer#: NONE To: MIKE THAYER Recvd: NO Subj: Re: Calculating Angles Conf: (2) Quik_Bas

MT>DRAW"S4 TA"+STR$(Angle%)'Use an angleThe mathematical solution says that the angle, given two points at (x1%,y1%) and (x2%,y2%) is given by ATN((y2% - y1%) / (x2% - x1%)). There are a few problems to watch out for: - the angle returned by ATN() is in radians. To get degrees, compute: Degrees% = Radians% * 180 / 3.141592654 - the formula assumes that x2% is always greater than x1% (i.e. the point that is further to the LEFT is always (x1%,y1%), so that returned angles are in the range (-90 degrees to 90 degrees). - when x1% and x2% are equal, the line is vertical, so the angle is plus or minus 90 degrees. The formula as given above would give a division by 0, so watch that case. - screen modes other thanSCREEN11 and 12 do not respect the 4/3 visual aspect ratio of the screen (i.e. a pixel is not round but oval in the vertical direction) so the calculated angles may not look visually correct. --- ME2_1104 * Origin: Out of String Space - the Final Frontier (Fidonet 1:163/506.2)

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