2016 Update
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Tina Müller
parent
948b86eafa
commit
dcf5d15da3
7965 changed files with 139854 additions and 31002 deletions
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/*REXX program plots/draws line segments using the Bresenham's line algorithm.*/
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@.='·' /*fill the array with middle─dots chars*/
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parse arg data /*allow the data point specifications. */
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if data='' then data= '(1,8) (8,16) (16,8) (8,1) (1,8)' /*◄────rhombus.*/
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data=translate(data,,'()[]{}/,:;') /*elide chaff from the data points. */
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/* [↓] data point pairs ───► !.array. */
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do points=1 while data\='' /*put the data points into an array (!)*/
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parse var data x y data; !.points=x y /*extract the line segments. */
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if points==1 then do; minX=x; maxX=x; minY=y; maxY=y; end /*1st case.*/
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minX=min(minX,x); maxX=max(maxX,x); minY=min(minY,y); maxY=max(maxY,y)
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end /*points*/ /* [↑] data points pairs in array !. */
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border=2 /*border: is extra space around plot. */
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minX=minX-border*2; maxX=maxX+border*2 /*min and max X for the plot display.*/
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minY=minY-border ; maxY=maxY+border /* " " " Y " " " " */
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do x=minX to maxX; @.x.0='─'; end /*draw a dash from left ───► right.*/
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do y=minY to maxY; @.0.y='│'; end /*draw a pipe from lowest ───► highest*/
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@.0.0='┼' /*define the plot's origin axis point. */
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do seg=2 to points-1; _=seg-1 /*obtain the X and Y line coördinates*/
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call draw_line !._, !.seg /*draw (plot) a line segment. */
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end /*seg*/ /* [↑] drawing the line segments. */
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/* [↓] display the plot to terminal. */
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do y=maxY to minY by -1; _= /*display the plot one line at a time. */
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do x=minX to maxX /*build line by examining the X axis.*/
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_=_ || @.x.y /*construct/build a line of the plot. */
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end /*x*/ /* (a line is a "row" of points.) */
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say _ /*display a line of the plot──►terminal*/
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end /*y*/ /* [↑] all done plotting the points. */
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exit /*stick a fork in it, we're all done. */
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/*────────────────────────────────────────────────────────────────────────────*/
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draw_line: procedure expose @.; parse arg x y,xf yf; plotChar='Θ'
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dx=abs(xf-x); if x<xf then sx=+1 /*obtain X range, determine the slope*/
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else sx=-1
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dy=abs(yf-y); if y<yf then sy=+1 /*obtain Y range, determine the slope*/
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else sy=-1
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err=dx-dy /*calculate error between adjustments. */
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do forever; @.x.y=plotChar /*plot the points until it's complete. */
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if x=xf & y=yf then return /*are the plot points at the finish? */
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err2=err+err /*addition is faster than: err*2. */
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if err2 > -dy then do; err=err-dy; x=x+sx; end
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if err2 < dx then do; err=err+dx; y=y+sy; end
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/*REXX program plots/draws line segments using the Bresenham's line (2D) algorithm. */
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parse arg data /*obtain optional arguments from the CL*/
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if data='' then data= "(1,8) (8,16) (16,8) (8,1) (1,8)" /* ◄──── a rhombus.*/
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data=translate(data, , '()[]{}/,:;') /*elide chaff from the data points. */
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@.='·' /*fill the array with middle─dots chars*/
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do points=1 while data\='' /*put the data points into an array (!)*/
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parse var data x y data; !.points=x y /*extract the line segments. */
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if points==1 then do; minX=x; maxX=x; minY=y; maxY=y; end /*1st case.*/
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minX=min(minX,x); maxX=max(maxX,x); minY=min(minY,y); maxY=max(maxY,y)
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end /*points*/ /* [↑] data points pairs in array !. */
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border=2 /*border: is extra space around plot. */
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minX=minX-border*2; maxX=maxX+border*2 /*min and max X for the plot display.*/
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minY=minY-border ; maxY=maxY+border /* " " " Y " " " " */
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do x=minX to maxX; @.x.0='─'; end /*draw a dash from left ───► right.*/
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do y=minY to maxY; @.0.y='│'; end /*draw a pipe from lowest ───► highest*/
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@.0.0='┼' /*define the plot's origin axis point. */
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do seg=2 to points-1; _=seg-1 /*obtain the X and Y line coördinates*/
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call draw_line !._, !.seg /*draw (plot) a line segment. */
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end /*seg*/ /* [↑] drawing the line segments. */
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/* [↓] display the plot to terminal. */
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do y=maxY to minY by -1; _= /*display the plot one line at a time. */
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do x=minX to maxX; _=_ || @.x.y /*construct/build a line of the plot. */
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end /*x*/ /* (a line is a "row" of points.) */
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say _ /*display a line of the plot──►terminal*/
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end /*y*/ /* [↑] all done plotting the points. */
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exit /*stick a fork in it, we're all done. */
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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draw_line: procedure expose @.; parse arg x y,xf yf; plotChar='Θ'
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dx=abs(xf-x); if x<xf then sx= +1 /*obtain X range, determine the slope*/
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else sx= -1 /* negative slope. */
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dy=abs(yf-y); if y<yf then sy= +1 /*obtain Y range, determine the slope*/
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else sy= -1 /* negative slope. */
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err=dx-dy /*calculate error between adjustments. */
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do forever; @.x.y=plotChar /*plot the points until it's complete. */
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if x=xf & y=yf then return /*are the plot points at the finish? */
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err2=err+err /*addition is faster than: err*2. */
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if err2 > -dy then do; err=err-dy; x=x+sx; end
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if err2 < dx then do; err=err+dx; y=y+sy; end
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end /*forever*/
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