Total circles area: Difference between revisions
New post using the scanline method, in addition to an existing post using the recursive subdivision of space method.
m (Minor code improvement.) |
(New post using the scanline method, in addition to an existing post using the recursive subdivision of space method.) |
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}</syntaxhighlight>
Alternative example using the Scanline method.
<syntaxhighlight lang="java">
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
public final class CirclesTotalArea {
public static void main(String[] args) {
final double precision = 0.000_001;
System.out.println(String.format("%s%.8f", "Approximate area = ", areaScan(precision)));
}
private static double areaScan(double precision) {
List<Double> valuesY = new ArrayList<Double>();
for ( Circle circle : circles ) {
valuesY.add(circle.centreY + circle.radius);
}
for ( Circle circle : circles ) {
valuesY.add(circle.centreY - circle.radius);
}
final double min = valuesY.stream().min(Double::compare).get();
final double max = valuesY.stream().max(Double::compare).get();
final long minY = (long) Math.floor(min / precision);
final long maxY = (long) Math.ceil(max / precision);
double totalArea = 0.0;
for ( long i = minY; i <= maxY; i++ ) {
final double y = i * precision;
double right = Double.NEGATIVE_INFINITY;
List<PairX> pairsX = new ArrayList<PairX>();
for ( Circle circle : circles ) {
if ( Math.abs(y - circle.centreY) < circle.radius ) {
pairsX.add(horizontalSection(circle, y));
}
}
Collections.sort(pairsX, (one, two) -> Double.compare(one.x1, two.x1) );
for ( PairX pairX : pairsX ) {
if ( pairX.x2 > right ) {
totalArea += pairX.x2 - Math.max(pairX.x1, right);
right = pairX.x2;
}
}
}
return totalArea * precision;
}
private static PairX horizontalSection(Circle circle, double y) {
final double value = circle.radius * circle.radius - ( y - circle.centreY ) * ( y - circle.centreY );
final double deltaX = Math.sqrt(value);
return new PairX(circle.centreX - deltaX, circle.centreX + deltaX);
}
private static record PairX(double x1, double x2) {}
private static record Circle(double centreX, double centreY, double radius) {}
private static final List<Circle> circles = List.of(
new Circle( 1.6417233788, 1.6121789534, 0.0848270516),
new Circle(-1.4944608174, 1.2077959613, 1.1039549836),
new Circle( 0.6110294452, -0.6907087527, 0.9089162485),
new Circle( 0.3844862411, 0.2923344616, 0.2375743054),
new Circle(-0.2495892950, -0.3832854473, 1.0845181219),
new Circle( 1.7813504266, 1.6178237031, 0.8162655711),
new Circle(-0.1985249206, -0.8343333301, 0.0538864941),
new Circle(-1.7011985145, -0.1263820964, 0.4776976918),
new Circle(-0.4319462812, 1.4104420482, 0.7886291537),
new Circle( 0.2178372997, -0.9499557344, 0.0357871187),
new Circle(-0.6294854565, -1.3078893852, 0.7653357688),
new Circle( 1.7952608455, 0.6281269104, 0.2727652452),
new Circle( 1.4168575317, 1.0683357171, 1.1016025378),
new Circle( 1.4637371396, 0.9463877418, 1.1846214562),
new Circle(-0.5263668798, 1.7315156631, 1.4428514068),
new Circle(-1.2197352481, 0.9144146579, 1.0727263474),
new Circle(-0.1389358881, 0.1092805780, 0.7350208828),
new Circle( 1.5293954595, 0.0030278255, 1.2472867347),
new Circle(-0.5258728625, 1.3782633069, 1.3495508831),
new Circle(-0.1403562064, 0.2437382535, 1.3804956588),
new Circle( 0.8055826339, -0.0482092025, 0.3327165165),
new Circle(-0.6311979224, 0.7184578971, 0.2491045282),
new Circle( 1.4685857879, -0.8347049536, 1.3670667538),
new Circle(-0.6855727502, 1.6465021616, 1.0593087096),
new Circle( 0.0152957411, 0.0638919221, 0.9771215985)
);
}
</syntaxhighlight>
{{ out }}
<pre>
Approximate area = 21.56503660
</pre>
=={{header|jq}}==
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