Initial data commit

Task/Bitmap-Bresenhams-line-algorithm/PL-I/bitmap-bresenhams-line-algorithm-1.pli

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+/* Draw a line from (x0, y0) to (x1, y1).   13 May 2010 */
+/* Based on Rosetta code proforma. */
+
+   /* Declarations for image and selected color, for 4-bit colors. */
+   declare image(40,40) bit (4), color bit (4) static initial ('1000'b);
+
+draw_line: procedure (xi, yi, xf, yf );
+   declare (xi, yi, xf, yf) fixed binary (31) nonassignable;
+   declare (x0, y0, x1, y1) fixed binary (31);
+   declare (deltax, deltay, x, y, ystep) fixed binary;
+   declare (error initial (0), delta_error) float;
+   declare steep bit (1);
+
+   x0 = xi; y = YI; y0 = yi; x1 = xf; y1 = yf;
+   steep = abs(y1 - y0) > abs (x1 - x0);
+   if steep then
+      do; call swap (x0, y0); call swap (x1, y1); end;
+   if x0 > x1 then
+      do; call swap (x0, x1); call swap (y0, y1); end;
+   deltax = x1 - x0; deltay = abs(y1 - y0);
+   delta_error = deltay/deltax;
+   if y0 < y1 then ystep = 1; else ystep = -1;
+   do x = x0 to x1;
+       if steep then image(y, x) = color; else image(x, y) = color;
+       if steep then put skip list (y, x); else put skip list (x, y);
+       error = error + delta_error;
+       if error >= 0.5 then do; y = y + ystep; error = error - 1; end;
+   end;
+
+swap: procedure (a, b);
+   declare (a, b) fixed binary (31);
+   declare t fixed binary (31);
+   t = a; a = b; b = t;
+end swap;
+
+end draw_line;

Task/Bitmap-Bresenhams-line-algorithm/PL-I/bitmap-bresenhams-line-algorithm-2.pli

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+..........|..........
+..........|..........
+..........|..........
+..........|..........
+..........|..........
+..........|..........
+..........|.........*
+..........|.......**.
+..........|.....**...
+..........|...**.....
+----------+-**-------
+..........**.........
+........**|..........
+.......*..|..........
+..........|..........
+..........|..........
+..........|..........
+..........|..........
+..........|..........
+..........|..........
+..........|..........

Task/Bitmap-Bresenhams-line-algorithm/PL-I/bitmap-bresenhams-line-algorithm-3.pli

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+*process source xref or(!);
+ brbn:Proc Options(main);
+ /*********************************************************************
+ * 21.05.2014  Walter Pachl
+ * Implementing the pseudo code of
+ *    http://en.wikipedia.org/wiki/Bresenham%27s_line_algorithm
+ * under 'Simplification' (see also REXX version 2)
+ *********************************************************************/
+grid.=
+ dcl image(-2:7,-4:11) char(1);
+ image='.';
+ image(*,0)='-';
+ image(0,*)='|';
+ image(0,0)='+';
+ call draw_line(-1,-3,6,10);
+ Dcl (i,j) Bin Fixed(31);
+ Do j=11 To -4 By -1;
+   Put Edit(j,' ')(Skip,f(2),a);
+   Do i=-2 To 7;
+     Put Edit(image(i,j))(a);
+     End;
+   End;
+ Put Edit('   2101234567')(Skip,a);
+
+ draw_line: procedure (x0,y0,x1,y1);
+ dcl (x0,y0,x1,y1) fixed binary(31);
+ dcl (dx,dy,sx,sy,err,e2) fixed binary(31);
+
+ dx = abs(x1-x0);
+ dy = abs(y1-y0);
+ if x0 < x1 then sx = 1;
+            else sx = -1;
+ if y0 < y1 then sy = 1;
+            else sy = -1;
+ err = dx-dy;
+
+ Do Until(x0=x1&y0=y1);
+   image(x0,y0)='X';
+   e2=err*2;
+   if e2>-dy then do;
+     err=err-dy;
+     x0=x0+sx;
+     End;
+   if e2<dx then do;
+     err=err+dx;
+     y0=y0+sy;
+     End;
+   End;
+ image(x0,y0)='X';
+ end;
+ end;