A-M baby

Task/Bitmap-Bresenhams-line-algorithm/J/bitmap-bresenhams-line-algorithm-1.j

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+thru=: <./ + -~ i.@+ _1 ^ >        NB. integers from x through y
+
+NB.*getBresenhamLine v Returns points for a line given start and end points
+NB. y is: y0 x0 ,: y1 x1
+getBresenhamLine=: monad define
+  steep=. ([: </ |@-~/) y
+  points=. |."1^:steep y
+  slope=. %~/ -~/ points
+  ypts=. thru/ {."1 points
+  xpts=. ({: + 0.5 <.@:+ slope * ypts - {.) {.points
+  |."1^:steep ypts,.xpts
+)
+
+NB.*drawLines v Draws lines (x) on image (y)
+NB. x is: 2-item list (start and end points) ; (color)
+drawLines=: (1&{:: ;~ [: ; [: <@getBresenhamLine"2 (0&{::))@[ setPixels ]