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charts.lines: add 2-point-chunk

char-rename
Alexander Iljin 2017-01-13 23:31:47 +03:00 committed by John Benediktsson
parent e11cf1a60b
commit 48304ce5b5
1 changed files with 16 additions and 0 deletions
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lines/lines.factor
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@ -114,6 +114,22 @@ ALIAS: y second
: (drawable-chunks) ( chunks min max -- chunks )
'[ first second _ _ between? ] filter harvest ;
: calc-point-y ( slope y point -- xy ) over [ calc-x ] dip 2array ;
: xyy>chunk ( x y1 y2 -- chunk )
[ over ] dip 2array [ 2array ] dip 2array ;
:: 2-point-chunk ( left right ymin ymax -- chunk )
left last :> left-point right first :> right-point
left-point x right-point x = [
left-point x ymin ymax xyy>chunk
] [
left-point right-point calc-line-slope :> slope
slope ymin left-point calc-point-y
slope ymax left-point calc-point-y
left-point y right-point y > [ swap ] when 2array
] if ;
! Split data into chunks to be drawn within the [ymin,ymax] limits.
! Return the (empty?) sequence of chunks, possibly with some new
! points at ymin and ymax at the gap bounds.