B-spline: Difference between revisions
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* [https://www.cl.cam.ac.uk/teaching/2000/AGraphHCI/SMEG/node4.html B-splines]
<br><br>
=={{header|ALGOL 68}}==
{{Trans|Lua}}Which is {{Trans|Wren}}Suppresses unused parts of the plot.
<syntaxhighlight lang="algol68">
# mode to hold a B Spline #
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[ lb : ub ]INT range;
FOR n FROM lb TO ub DO range[ n ] := n OD;
END # uniform knot vector # ;
PROC calculate bspline = ( REF BSPLINE bs, INT i, k, x )REAL:
THEN ABS ( ( t OF bs )[ i ] <= x AND x < ( t OF bs )[ i + 1 ] )
PROC helper = ( REF BSPLINE bs, INT i, k, x )REAL:
IF ( t OF bs )[ i + k ] /= ( t OF bs )[ i ]
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REAL sum x := 0;
REAL sum y := 0;
REAL f = calculate bspline( bs, i, k OF bs, x );
sum x +:= f * ( control points OF bs )[ i, 1 ];
sum y +:= f * ( control points OF bs )[ i, 2 ]
OD;
points[ x, 2 ] := round( sum y )
OD;
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INT x := x0;
INT y := y0;
INT dy := ABS ( y2 - y );
INT dir y = IF y2 > y THEN 1 ELSE -1 FI;
dx *:= 2;
dy *:= 2;
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PROC plot line = ( REF[,]BOOL plot, INT x1, y1, x2, y2 )VOID:
, ( REF[,]BOOL plot, INT x, INT y )VOID: IF x >= 0
AND y >= 0
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AND y < 2 UPB plot
THEN plot[ x + 1, y + 1 ] := TRUE
);
PROC plot bspline = ( REF BSPLINE bs, REF[,]BOOL plot, REAL scale x, scale y )VOID:
IF k OF bs > n OF bs OR k OF bs < 1 THEN
print( ( "k (= ", whole( k OF bs, 0 ), ") can't be more than ", whole( n OF bs, 0 )
print( ( " or less than 1.", newline ) );
stop
ELSE
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)
OD
# print the plot - outputs @ or blank depending on whether the point is plotted or not #
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);
INT k = 4; # Polynomial degree is one less than this i.e. cubic. #
BSPLINE bs := ( control points
, UPB control points
, k
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plot bspline( bs, plot, scale x, scale y );
print plot( plot )
END
</syntaxhighlight>
{{out}}
leading blank lines removed...
<pre>
@@@@
@@@@
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=={{header|Julia}}==
Choose BSpline D of 2, ie degree 1.
<
Point(t::Tuple) = Vec2(Float64(t[1]), Float64(t[2]))
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(208, 254), (241, 330), (164,252), (69, 278), (139, 208), (72, 148), (168, 172)])
plt = plot(map(a -> a.x, controlpoints), map(a -> a.y, controlpoints))
savefig(plt, "BSplineplot.png")</
=={{header|Lua}}==
{{trans|Wren}}
<
local range = {}
for n = from, to do table.insert(range, n) end
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plotBspline(bspline, plot)
printPlot(plot)</
{{out}}
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@@@
</pre>
=={{header|Mathematica}}/{{header|Wolfram Language}}==
<
BSplineCurve[{{171, 171}, {185, 111}, {202, 109}, {202, 189}, {328,
160}, {208, 254}, {241, 330}, {164, 252}, {69, 278}, {139,
208}, {72, 148}, {168, 172}}, SplineClosed -> True,
SplineDegree -> 2]]</
{{out}}
Outputs a graphical representation of a B-spline.
=={{header|Perl}}==
{{trans|Raku}}
<
use warnings;
use Class::Struct;
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}
$cr->stroke;
$surf->write_to_png($OUTPUT);</
Output: [https://raw.githubusercontent.com/SqrtNegInf/Rosettacode-Perl-Smoke/master/ref/b-spline.png b-spline.png] (offsite image)
=={{header|Phix}}==
{{trans|Wren}}
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{{libheader|Phix/online}}
You can run this online [http://phix.x10.mx/p2js/bspline.htm here].
<!--<
<span style="color: #000080;font-style:italic;">--
-- demo\rosetta\B-spline.exw
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<span style="color: #000000;">main</span><span style="color: #0000FF;">()</span>
<!--</
=={{header|Processing}}==
<syntaxhighlight lang="java">
//Aamrun, 26th June 2022
int abscissae[]={171,185,202,202,328,208,241,164,69,139,72,168};
int ordinates[] = {171,111,109,189 ,160,254 ,330 ,252,278 ,208 ,148 ,172};
void setup() {
size(450, 450);
background(255);
smooth();
noFill();
stroke(0);
beginShape();
for(int i=0;i<abscissae.length;i++){
curveVertex(abscissae[i], ordinates[i]);
}
endShape();
fill(255, 0, 0);
noStroke();
for (int i = 0; i < abscissae.length; i ++) {
ellipse(abscissae[i], ordinates[i], 3, 3);
}
}
</syntaxhighlight>
=={{header|Raku}}==
A minimal translation of [https://www.cypherpunk.at/download/bspline/bspline_1.1.tbz2 this C program], by [https://github.com/rahra Bernhard R. Fischer].
<syntaxhighlight lang="raku"
use Cairo;
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};
.write_png(OUTPUT) and die # C return
}</
Output: [https://drive.google.com/file/d/1dInRJeecA18meybDF2D0usEaWMGFqoBj/view (Offsite image file) ]
=={{header|Wren}}==
{{libheader|DOME}}
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If one uses a value for k of 1, then the script will simply plot the control points as in the Julia example.
<
import "graphics" for Canvas, Color
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]
var k = 4 // polynomial degree is one less than this i.e. cubic
var Game = BSpline.new(400, 400, cpoints, k)</
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