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Another update from ingydotnet^djgoku

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Ingy döt Net 2015-11-18 06:14:39 +00:00
parent 91df62d461
commit 948b86eafa
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Task/Bitmap-Bresenhams-line-algorithm/REXX/bitmap-bresenhams-line-algorithm-1.rexx
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@ -1,43 +1,42 @@
/*REXX program plots/draws line(s) using the Bresenham's line algorithm.*/
@.='·' /*fill the array with middle─dots*/
parse arg data /*allow data point specifications*/
if data='' then data= '(1,8) (8,16) (16,8) (8,1) (1,8)' /*rhombus*/
data=translate(data,,'()[]{}/,:;') /*elide chaff from data points. */
/* [↓] data pt pairs ──► !.array.*/
do points=1 while data\='' /*put data points into an array. */
parse var data x y data; !.points=x y /*extract line segments.*/
if points==1 then do; minX=x; maxX=x; minY=y; maxY=y; end /*1st case*/
minX=min(minX,x); maxX=max(maxX,x); minY=min(minY,y); maxY=max(maxY,y)
end /*points*/ /* [↑] data points pairs in !. */
/*REXX program plots/draws line segments using the Bresenham's line algorithm.*/
@.='·' /*fill the array with middle─dots chars*/
parse arg data /*allow the data point specifications. */
if data='' then data= '(1,8) (8,16) (16,8) (8,1) (1,8)' /*◄────rhombus.*/
data=translate(data,,'()[]{}/,:;') /*elide chaff from the data points. */
/* [↓] data point pairs ───► !.array. */
do points=1 while data\='' /*put the data points into an array (!)*/
parse var data x y data; !.points=x y /*extract the line segments. */
if points==1 then do; minX=x; maxX=x; minY=y; maxY=y; end /*1st case.*/
minX=min(minX,x); maxX=max(maxX,x); minY=min(minY,y); maxY=max(maxY,y)
end /*points*/ /* [↑] data points pairs in array !. */
border=2 /*border=extra space around plot.*/
minX=minX-border*2; maxX=maxX+border*2 /*min,max X for the plot display.*/
minY=minY-border ; maxY=maxY+border /* " " Y " " " " */
do x=minX to maxX; @.x.0='─'; end /*draw dash from left──► right.*/
do y=minY to maxY; @.0.y='│'; end /*draw pipe from lowest──►highest*/
@.0.0='┼' /*define the plot's axis point. */
do seg=2 to points-1; _=seg-1 /*obtain the X,Y line coördinates*/
call draw_line !._, !.seg /*draw (plot) a line segment. */
end /*seg*/ /* [↑] drawing the line segments*/
/* [↓] display the plot to term.*/
do y=maxY to minY by -1; _= /*display plot one line at a time*/
do x=minX to maxX /*traipse throught the X axis. */
_=_ || @.x.y /*construct a "line" of the plot.*/
end /*x*/ /*(a line is a "row" of points.) */
say _ /*display a "line" of the plot. */
end /*y*/ /* [↑] all done ploting the pts.*/
exit /*stick a fork in it, we're done.*/
/*────────────────────────────────DRAW_LINE subroutine──────────────────*/
draw_line: procedure expose @.; parse arg x y,xf yf; plotChar='Θ'
dx=abs(xf-x); if x<xf then sx=+1 /*obtain X range, determine slope*/
border=2 /*border: is extra space around plot. */
minX=minX-border*2; maxX=maxX+border*2 /*min and max X for the plot display.*/
minY=minY-border ; maxY=maxY+border /* " " " Y " " " " */
do x=minX to maxX; @.x.0='─'; end /*draw a dash from left ───► right.*/
do y=minY to maxY; @.0.y='│'; end /*draw a pipe from lowest ───► highest*/
@.0.0='┼' /*define the plot's origin axis point. */
do seg=2 to points-1; _=seg-1 /*obtain the X and Y line coördinates*/
call draw_line !._, !.seg /*draw (plot) a line segment. */
end /*seg*/ /* [↑] drawing the line segments. */
/* [↓] display the plot to terminal. */
do y=maxY to minY by -1; _= /*display the plot one line at a time. */
do x=minX to maxX /*build line by examining the X axis.*/
_=_ || @.x.y /*construct/build a line of the plot. */
end /*x*/ /* (a line is a "row" of points.) */
say _ /*display a line of the plot──►terminal*/
end /*y*/ /* [↑] all done plotting the points. */
exit /*stick a fork in it, we're all done. */
/*────────────────────────────────────────────────────────────────────────────*/
draw_line: procedure expose @.; parse arg x y,xf yf; plotChar='Θ'
dx=abs(xf-x); if x<xf then sx=+1 /*obtain X range, determine the slope*/
else sx=-1
dy=abs(yf-y); if y<yf then sy=+1 /*obtain Y range, determine slope*/
dy=abs(yf-y); if y<yf then sy=+1 /*obtain Y range, determine the slope*/
else sy=-1
err=dx-dy /*calc error between adjustments.*/
do forever; @.x.y=plotChar /*plot the points until complete.*/
if x=xf & y=yf then leave /*are plot points at the finish? */
err2=err+err /*this is faster than err*2. */
if err2 > -dy then do; err=err-dy; x=x+sx; end
if err2 < dx then do; err=err+dx; y=y+sy; end
err=dx-dy /*calculate error between adjustments. */
do forever; @.x.y=plotChar /*plot the points until it's complete. */
if x=xf & y=yf then return /*are the plot points at the finish? */
err2=err+err /*addition is faster than: err*2. */
if err2 > -dy then do; err=err-dy; x=x+sx; end
if err2 < dx then do; err=err+dx; y=y+sy; end
end /*forever*/
return