46 lines
1.3 KiB
Factor
46 lines
1.3 KiB
Factor
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! Copyright (c) 2012 Anonymous
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! See http://factorcode.org/license.txt for BSD license.
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USING: accessors arrays kernel locals math math.functions
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math.ranges math.vectors rosetta-code.bitmap sequences
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ui.gadgets ;
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IN: rosetta-code.bitmap-line
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! http://rosettacode.org/wiki/Bitmap/Bresenham%27s_line_algorithm
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! Using the data storage type defined on this page for raster
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! graphics images, draw a line given 2 points with the Bresenham's
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! algorithm.
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:: line-points ( pt1 pt2 -- points )
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pt1 first2 :> y0! :> x0!
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pt2 first2 :> y1! :> x1!
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y1 y0 - abs x1 x0 - abs > :> steep
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steep [
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y0 x0 y0! x0!
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y1 x1 y1! x1!
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] when
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x0 x1 > [
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x0 x1 x0! x1!
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y0 y1 y0! y1!
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] when
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x1 x0 - :> deltax
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y1 y0 - abs :> deltay
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0 :> current-error!
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deltay deltax / abs :> deltaerr
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0 :> ystep!
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y0 :> y!
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y0 y1 < [ 1 ystep! ] [ -1 ystep! ] if
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x0 x1 1 <range> [
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y steep [ swap ] when 2array
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current-error deltaerr + current-error!
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current-error 0.5 >= [
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ystep y + y!
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current-error 1 - current-error!
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] when
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] { } map-as ;
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! Needs rosetta-code.bitmap for the set-pixel function and to create the image
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: draw-line ( {R,G,B} pt1 pt2 image -- )
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[ line-points ] dip
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[ set-pixel ] curry with each ;
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