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Bitmap/Bresenham's line algorithm: Difference between revisions
m
→{{header|REXX}}: changed some comments, used faster assignments, made the drawLine procedure simpler.
m (→version 1: changed indentation for subroutine, split do/end groups, added/changed whitespace and comments, used template for the output section.) |
m (→{{header|REXX}}: changed some comments, used faster assignments, made the drawLine procedure simpler.) |
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Line 3,327:
if data='' then data= "(1,8) (8,16) (16,8) (8,1) (1,8)" /* ◄──── a rhombus.*/
data= translate(data, , '()[]{}/,:;') /*elide chaff from the data points. */
@.= '·' /*
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. */
Line 3,352:
exit /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
drawLine: procedure expose @.;
dx= abs(xf-x); if x<xf then sx=
dy= abs(yf-y); if y<yf then sy= 1 /* " Y
else sy= -1 /* negative slope. */▼
err= dx - dy /*calculate error between adjustments. */
do forever; @.x.y=
if x=xf & y=yf then return /*are the plot points at the finish? */
err2= err + err /*calculate double the error
if err2 > -dy then do; err= err - dy; x= x + sx; end
if err2 < dx then do; err= err + dx; y= y + sy; end
Line 3,389 ⟶ 3,387:
</pre>
=== version 2 ===
<lang rexx>/* REXX ***************************************************************
* 21.05.2014 Walter Pachl
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