Script Library: 1213 scripts
 

bresenham.r

REBOL [ title: "Bresenham Line" file: %bresenham.r author: "Semseddin (Endo) Moldibi" version: 1.0.0 date: 2010-08-08 purpose: "Returns all pairs in a block for line specified by P0/P1." Library: [ level: 'beginner platform: 'all type: 'function domain: 'math tested-under: none support: "semseddin/at/gmail.com" license: 'public-domain see-also: none ] ] BresenhamLine: funct [p0 [pair!] p1 [pair!]] [ result: make block! 32 if p0 = p1 [return append result p0] x0: p0/x x1: p1/x y0: p0/y y1: p1/y steep: greater? abs (y1 - y0) abs (x1 - x0) if steep [ t: x0 x0: y0 y0: t t: x1 x1: y1 y1: t ] if x0 > x1 [ t: x0 x0: x1 x1: t t: y0 y0: y1 y1: t ] deltax: x1 - x0 deltay: abs (y1 - y0) error: 0 deltaerr: deltay / deltax ystep: either y0 < y1 [1] [-1] y: y0 for x x0 x1 1 [ p: either steep [as-pair y x] [as-pair x y] append result p error: error + deltaerr if error >= 0.5 [ y: y + ystep error: error - 1.0 ] ] result ] ;probe BresenhamLine 13x5 25x17 ;halt
halt ;; to terminate script if DO'ne from webpage