Alternative circle routine
'CIRCLE.BI '** '** QB64 replacement CIRCLE command. '** '** The CIRCLE command in QB64 has a few issues: '** '** - radian end points are not calculate properly when creating arcs '** - center line to radian end points do not close properly due to previous bug listed '** '** This circle command replacement works very similiarly to the native CIRCLE command: '** '** SYNTAX: CIRCLES x%, y%, radius!, color~&, start_radian!, end_radian!, aspect_ratio! '** '** x% - center X coordinate of circle '** y% - center Y coordinate of circle '** radius! - the radius of the circle '** color~& - the circle's color '** start_radian! - the radian on circle curcunference to begin drawing at '** end_radian! - the radian on circle circumference to end drawing at '** aspect_ratio! - the aspect ratio of the circle '** '** NOTE: unlike the native CIRCLE command, all arguments MUST be supplied. For example, '** with the native command this will draw a perfect circle with the default color, '** start radian, end radian and aspect ratio: '** '** CIRCLE (319, 239), 100 '** '** To do the same thing with this replacement command you must supply everything: '** '** CIRCLES 319, 239, 100, _RGB32(255, 255, 255), 0, 0, 0 '** '** ACKNOWLEGEMENTS: The FOR/NEXT step formula was was written by Codeguy for Unseen '** Machine's Visual library EllipseXS command. Specifically: '** MinStep! = 1 / (2 * 3.1415926535 * Radius!) '** '** '** Includes performance tweaks made by SMcNeill on 02/02/13 - specifically removing a few redundant * -1 '** statements and converting the FOR/NEXT loop to a DO loop for a ~3% increase in performance. '** '** Corrected bug in which variables being passed in were being modified and passed back - 02/02/13 '** SUB CIRCLES (cx%, cy%, r!, c~&, s!, e!, a!) DIM s%, e%, nx%, ny%, xr!, yr!, st!, en!, asp! ' local variables used st! = s! ' copy start radian to local variable en! = e! ' copy end radian to local variable asp! = a! ' copy aspect ratio to local variable IF asp! <= 0 THEN asp! = 1 ' keep aspect ratio between 0 and 4 IF asp! > 4 THEN asp! = 4 IF asp! < 1 THEN xr! = r! * asp! * 4 ELSE xr! = r! ' calculate x/y radius based on aspect ratio IF asp! > 1 THEN yr! = r! * asp! ELSE yr! = r! IF st! < 0 THEN s% = -1: st! = -st! ' remember if line needs drawn from center to start radian IF en! < 0 THEN e% = -1: en! = -en! ' remember if line needs drawn from center to end radian IF s% THEN ' draw line from center to start radian? nx% = cx% + xr! * COS(st!) ' yes, compute starting point on circle's circumference ny% = cy% + yr! * -SIN(st!) LINE (cx%, cy%)-(nx%, ny%), c~& ' draw line from center to radian END IF IF en! <= st! THEN en! = en! + 6.2831852 ' come back around to proper location (draw counterclockwise) stepp! = 0.159154945806 / r! c! = st! ' cycle from start radian to end radian DO nx% = cx% + xr! * COS(c!) ' compute next point on circle's circumfrerence ny% = cy% + yr! * -SIN(c!) PSET (nx%, ny%), c~& ' draw the point c! = c! + stepp! LOOP UNTIL c! >= en! IF e% THEN LINE -(cx%, cy%), c~& ' draw line from center to end radian if needed END SUB
