2016 Update
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Tina Müller
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7965 changed files with 139854 additions and 31002 deletions
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/*REXX program plots/draws a line using the Xiaolin Wu line algorithm.*/
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background = 'fa'x /*background char: middle-dot. */
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image. = background /*fill the array with middle-dots*/
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plotC = '░▒▓█' /*chars used for plotting points.*/
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EoE = 1000 /*EOE = End Of Earth, er... plot.*/
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do j=-EoE to +EoE /*draw grid from lowest──►highest*/
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image.j.0 = '─' /*draw the horizontal axis. */
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image.0.j = '│' /* " " verical " */
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end /*j*/
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image.0.0 = '┼' /*"draw" the axis origin (char). */
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parse arg xi yi xf yf . /*allow specifying line-end pts. */
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if xi=='' | xi==',' then xi = 1 /*if not specified, use default. */
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if yi=='' | yi==',' then yi = 2 /* " " " " " */
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if xf=='' | xf==',' then xf = 11 /* " " " " " */
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if yf=='' | yf==',' then yf = 12 /* " " " " " */
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minX=0; minY=0 /*used as limits for plotting. */
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maxX=0; maxY=0 /* " " " " " */
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call line_draw xi, yi, xf, yf /*call subroutine and draw line. */
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border = 2 /*allow additional space for plot*/
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minX=minX-border*2; maxX=maxX+border*2
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minY=minY-border ; maxY=maxY+border
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do y=maxY by -1 to minY; _= /*build a row*/
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do x=minX to maxX
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_=_ || image.x.y
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end /*x*/
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say _ /*display row*/
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end /*y*/
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exit /*stick a fork in it, we're done.*/
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/*────────────────────────────────DRAW_LINE subroutine──────────────────*/
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line_draw: procedure expose background image. minX maxX minY maxY plotC
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parse arg x1, y1, x2, y2; switchXY=0; dx=x2-x1
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dy=y2-y1
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if abs(dx)<abs(dy) then do
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parse value x1 y1 with y1 x1 /*swap x1 & y1*/
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parse value x2 y2 with y2 x2 /*swap x2 & y2*/
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parse value dx dy with dy dx /*swap dx & dy*/
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end
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if x2<x1 then do
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parse value x1 x2 with x2 x1 /*swap x1 & x2*/
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parse value y1 y2 with y2 y1 /*swap y1 & y2*/
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switchXY=1
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end
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/*REXX program plots/draws a line using the Xiaolin Wu line algorithm. */
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background='·' /*background character: a middle-dot. */
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image.=background /*fill the array with middle-dots. */
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plotC='░▒▓█' /*characters used for plotting points. */
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EoE=1000 /*EOE = End Of Earth, er, ··· graph. */
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do j=-EoE to +EoE /*define the graph: lowest ──► highest.*/
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image.j.0='─' /*define the graph's horizontal axis. */
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image.0.j='│' /* " " " verical " */
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end /*j*/
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image.0.0='┼' /*define the graph's axis origin (char)*/
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parse arg xi yi xf yf . /*allow specifying the line-end points.*/
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if xi=='' | xi=="," then xi= 1 /*Not specified? Then use the default.*/
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if yi=='' | yi=="," then yi= 2 /* " " " " " " */
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if xf=='' | xf=="," then xf=11 /* " " " " " " */
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if yf=='' | yf=="," then yf=12 /* " " " " " " */
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minX=0; minY=0 /*use these as the limits for plotting.*/
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maxX=0; maxY=0 /* " " " " " " " */
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call drawLine xi, yi, xf, yf /*invoke subroutine and graph the line.*/
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border=2 /*allow additional space (plot border).*/
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minX=minX-border*2; maxX=maxX+border*2 /* *2 preserves screen's aspect ratio.*/
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minY=minY-border ; maxY=maxY+border
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do y=maxY by -1 to minY; _= /*build a row.*/
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do x=minX to maxX; _=_ || image.x.y; end /*x*/
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say _ /*display row.*/
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end /*y*/ /*graph is cropped by the MINs and MAXs*/
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exit /*stick a fork in it, we're all done. */
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/*────────────────────────────────────────────────────────────────────────────*/
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drawLine: parse arg x1,y1,x2,y2; switchXY=0; dx=x2-x1
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dy=y2-y1
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if abs(dx) < abs(dy) then parse value x1 y1 x2 y2 dx dy with,
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y1 x2 y2 x2 dy dx
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if x2<x1 then parse value x1 x2 y1 y2 1 with,
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x2 x1 y2 y1 switchXY
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gradient=dy/dx
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xend=round(x1) /*◄─────────────────1st endpoint.══════════════*/
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yend=y1 + gradient*(xend-x1); xgap=1-fpart(x1 + .5)
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xpx11=xend; ypx11=floor(yend)
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intery=yend+gradient
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call plotXY xpx11, ypx11, brite(1-fpart(yend*xgap)), switchXY
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call plotXY xpx11, ypx11+1, brite( fpart(yend*xgap)), switchXY
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xend=round(x2) /*◄─────────────────2nd endpoint.══════════════*/
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yend=y2 + gradient*(xend-x2); xgap=fpart(x2 + .5)
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xpx12=xend; ypx12=floor(yend)
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call plotXY xpx12, ypx12 , brite(1-fpart(yend*xgap)), switchXY
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call plotXY xpx12, ypx12+1, brite( fpart(yend*xgap)), switchXY
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gradient = dy/dx
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xend = round(x1) /*────1st endpoint────────────────────*/
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yend = y1 + gradient * (xend-x1)
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intery = yend + gradient
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xgap = 1 - fpart(x1+.5)
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xpx11 = xend; ypx11 = floor(yend); ypx11_=ypx11+1
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call plotXY xpx11, ypx11, brite(1-fpart(yend*xgap)),switchXY
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call plotXY xpx11, ypx11_, brite( fpart(yend*xgap)),switchXY
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do x=xpx11+1 to xpx12-1 /*◄───draw the line.═════════════*/
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!intery=floor(intery)
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call plotXY x, !intery , brite(1-fpart(intery)), switchXY
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call plotXY x, !intery+1, brite( fpart(intery)), switchXY
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intery=intery+gradient
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end /*x*/
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return
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/*────────────────────────────────short subroutines and functions.────────────*/
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brite: return substr(background||plotC, 1+round(abs(arg(1))*length(plotC)),1)
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floor: parse arg ?; _=trunc(?); return _ - (?<0) * (?\=_)
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fpart: parse arg ?; return abs(? - trunc(?))
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round: return format(arg(1), , word(arg(2) 0, 1))
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xend = round(x2) /*────2nd endpoint────────────────────*/
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yend = y2 + gradient * (xend-x2)
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xgap = fpart(x2+.5)
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xpx12 = xend; ypx12 = floor(yend); ypx12_=ypx12+1
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call plotXY xpx12, ypx12, brite(1-fpart(yend*xgap)), switchXY
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call plotXY xpx12, ypx12_, brite( fpart(yend*xgap)), switchXY
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do x=xpx11+1 to xpx12-1 /*────draw the line───────────────────*/
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!intery = floor(intery)
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!intery_ = !intery+1
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call plotXY x, !intery, brite(1-fpart(intery)), switchXY
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call plotXY x, !intery_, brite( fpart(intery)), switchXY
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intery = intery + gradient
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end /*x*/
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return
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/*────────────────────────────────BRITE subroutine──────────────────────*/
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brite: procedure expose background plotC; parse arg p
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return substr(background || plotC, 1+round(abs(p)*length(plotC)), 1)
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/*────────────────────────────────PLOTXY subroutine─────────────────────*/
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plotXY: procedure expose image. minX maxX minY maxY
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parse arg xx, yy, bc, switchYX; if switchYX then parse arg yy, xx
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image.xx.yy=bc; minX=min(minX,xx); maxX=max(maxX,xx)
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minY=min(minY,yy); maxY=max(maxY,yy)
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return
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/*────────────────────────────────FLOOR subroutine──────────────────────*/
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floor: procedure; parse arg ?; _=trunc(?); return _-(?<0)*(?\=_)
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/*────────────────────────────────FPART subroutine──────────────────────*/
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fpart: procedure; parse arg ?; return abs(?-trunc(?))
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/*────────────────────────────────ROUND subroutine─────────arg2 is place*/
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round: return format(arg(1), , word(arg(2) 0, 1))
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plotXY: parse arg xx,yy,bc,switchYX; if switchYX then parse arg yy,xx
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image.xx.yy=bc; minX=min(minX,xx); maxX=max(maxX,xx)
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minY=min(minY,yy); maxY=max(maxY,yy)
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return
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