/*
 * #%L
 * Image processing operations for SciJava Ops.
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package org.scijava.ops.image.geom.geom3d;

import net.imglib2.mesh.Mesh;
import net.imglib2.mesh.Triangle;
import net.imglib2.type.numeric.real.DoubleType;

import org.apache.commons.math3.geometry.euclidean.threed.Vector3D;
import org.scijava.function.Computers;

/**
 * Generic implementation of {@code geom.boundarySize}.
 *
 * @author Tim-Oliver Buchholz (University of Konstanz)
 * @implNote op names='geom.boundarySize', label='Geometric (3D): Surface Area',
 *           priority='10000.'
 */
public class DefaultSurfaceArea implements Computers.Arity1<Mesh, DoubleType> {

	/**
	 * TODO
	 *
	 * @param input
	 * @param boundarySize
	 */
	@Override
	public void compute(final Mesh input, final DoubleType boundarySize) {
		double total = 0;
		for (final var tri : input.triangles()) {
			final var v0 = new Vector3D(tri.v0x(), tri.v0y(), tri.v0z());
			final var v1 = new Vector3D(tri.v1x(), tri.v1y(), tri.v1z());
			final var v2 = new Vector3D(tri.v2x(), tri.v2y(), tri.v2z());

			final var cross = v0.subtract(v1).crossProduct(v2.subtract(v0));
			final var norm = cross.getNorm();
			if (norm > 0) total += norm * 0.5;
		}
		boundarySize.set(total);
	}

}
