Sierpinski curve: Difference between revisions

Content added Content deleted
(Added Algol W)
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[https://gitlab.com/amarok8bit/action-rosetta-code/-/raw/master/images/Sierpinski_curve.png Screenshot from Atari 8-bit computer]
[https://gitlab.com/amarok8bit/action-rosetta-code/-/raw/master/images/Sierpinski_curve.png Screenshot from Atari 8-bit computer]

=={{header|ALGOL W}}==
Using code from the [[Sierpinski arrowhead curve]] task.<br>
Curve algorithm based on the XPL0 sample.
<syntaxhighlight lang="algolw">
begin % draw sierpinski curves using ascii art %
integer CANVAS_WIDTH;
CANVAS_WIDTH := 200;
begin
% the ascii art canvas and related items %
string(1) array canvas ( 1 :: CANVAS_WIDTH, 1 :: CANVAS_WIDTH );
integer heading, asciiX, asciiY, width, maxX, maxY, minX, minY;
% draw a line using ascii art - the length is ignored and the heading determines the %
% character to use %
% the position is updated %
procedure drawLine( real value length ) ;
begin
% stores the min and max coordinates %
procedure updateCoordinateRange ;
begin
if asciiX > maxX then maxX := asciiX;
if asciiY > maxY then maxY := asciiY;
if asciiX < minX then minX := asciiX;
if asciiY < minY then minY := asciiY
end updateCoordinateRange ;
if heading = 0 then begin
updateCoordinateRange;
canvas( asciiX, asciiY ) := "_";
asciiX := asciiX + 1
end
else if heading = 45 then begin
updateCoordinateRange;
canvas( asciiX, asciiY ) := "/";
asciiY := asciiY - 1;
asciiX := asciiX + 1
end
else if heading = 90 then begin
updateCoordinateRange;
canvas( asciiX, asciiY ) := "|";
asciiY := asciiY - 1
end
else if heading = 135 then begin
asciiX := asciiX - 1;
updateCoordinateRange;
canvas( asciiX, asciiY ) := "\";
asciiY := asciiY - 1
end
else if heading = 180 then begin
asciiX := asciiX - 1;
updateCoordinateRange;
canvas( asciiX, asciiY ) := "_"
end
else if heading = 225 then begin
asciiX := asciiX - 1;
asciiY := asciiY + 1;
updateCoordinateRange;
canvas( asciiX, asciiY ) := "/"
end
else if heading = 270 then begin
asciiY := asciiY + 1;
updateCoordinateRange;
canvas( asciiX - 1, asciiY ) := "|";
end
else if heading = 315 then begin
asciiY := asciiY + 1;
updateCoordinateRange;
canvas( asciiX, asciiY ) := "\";
asciiX := asciiX + 1
end if_various_headings
end drawLine ;
% changes the heading by the specified angle ( in degrees ) - angle must be +/- 45 %
procedure turn( integer value angle ) ;
if angle > 0
then heading := ( heading + angle ) rem 360
else begin
heading := heading + angle;
if heading < 0 then heading := heading + 360
end tuen ;
% initialises the ascii art canvas %
procedure initArt ;
begin
heading := 0;
asciiX := CANVAS_WIDTH div 2;
asciiY := asciiX;
maxX := asciiX;
maxY := asciiY;
minX := asciiX;
minY := asciiY;
for x := 1 until CANVAS_WIDTH do for y := 1 until CANVAS_WIDTH do canvas( x, y ) := " "
end initArt ;
% shows the used parts of the canvas %
procedure drawArt ;
begin
for y := minY until maxY do begin
write();
for x := minX until maxX do writeon( canvas( x, y ) )
end for_y ;
write()
end drawIArt ;
% draws a sierpinski curve of the specified order and line length %
procedure sierpinskiCurve( integer value order ) ;
begin
% recursively draws a segment of the sierpinski curve %
procedure curve( integer value order; integer value angle ) ;
if 0 not = order then begin
turn( + angle );
curve( order - 1, - angle );
turn( - angle );
drawline( 1 );
if heading rem 180 = 0 then drawline( 1 );
turn( - angle );
curve( order - 1, - angle );
turn( + angle );
end curve ;
for Quad := 1 until 4 do begin
curve( order * 2, 45 );
turn( 45 );
drawline( 1 );
if heading rem 180 = 0 then drawline( 1 );
turn( 45 );
end for_Quad
end sierpinskiCurve ;
% draw curves %
i_w := 1; s_w := 0; % set output formatting %
for order := 3 do begin
write( "Sierpinski curve of order ", order );
write( "===========================" );
write();
initArt;
sierpinskiCurve( order );
drawArt
end for_order
end
end.
</syntaxhighlight>
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<pre>
Sierpinski curve of order 3
===========================

/\__/\ /\__/\ /\__/\ /\__/\
\ / \ / \ / \ /
| | | | | | | |
/ __ \__/ __ \ / __ \__/ __ \
\/ \ / \/ \/ \ / \/
| | | |
/\__/ __ \__/\ /\__/ __ \__/\
\ / \ / \ / \ /
| | | | | | | |
/ __ \ / __ \__/ __ \ / __ \
\/ \/ \/ \ / \/ \/ \/
| |
/\__/\ /\__/ __ \__/\ /\__/\
\ / \ / \ / \ /
| | | | | | | |
/ __ \__/ __ \ / __ \__/ __ \
\/ \ / \/ \/ \ / \/
| | | |
/\__/ __ \__/\ /\__/ __ \__/\
\ / \ / \ / \ /
| | | | | | | |
/ __ \ / __ \ / __ \ / __ \
\/ \/ \/ \/ \/ \/ \/ \/
</pre>


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