Meshes: Add boundingBoxMesh

Author: gselzer

src/main/java/net/imglib2/mesh/Meshes.java

@@ -75,7 +75,7 @@ public static RealPoint center( final Mesh m )
 	/**
 	 * Computes and returns an <b>oriented</b> bounding box {@link RealInterval}
 	 *
-	 * @param input
+	 * @param mesh
 	 * @return the output {@link Mesh}
 	 * @implNote op names="geom.boundingBox"
 	 */
@@ -103,6 +103,49 @@ public static RealInterval boundingBox( final net.imglib2.mesh.Mesh mesh )
 		return Intervals.createMinMaxReal( boundingBox[ 0 ], boundingBox[ 1 ], boundingBox[ 2 ], boundingBox[ 3 ], boundingBox[ 4 ], boundingBox[ 5 ] );
 	}
 
+	/**
+	 * Computes and returns an <b>oriented</b> bounding box {@link Mesh}
+	 *
+	 * @param input
+	 * @return the output {@link Mesh}
+	 * @implNote op names="geom.boundingBox"
+	 */
+	public static Mesh boundingBoxMesh(final Mesh input) {
+		RealInterval interval = boundingBox(input);
+		Mesh m = new NaiveDoubleMesh();
+		// BOTTOM VERTICES
+		long bbl = m.vertices().add(interval.realMin(0), interval.realMin(1), interval.realMin(2));
+		long bbr = m.vertices().add(interval.realMax(0), interval.realMin(1), interval.realMin(2));
+		long bfl = m.vertices().add(interval.realMin(0), interval.realMax(1), interval.realMin(2));
+		long bfr = m.vertices().add(interval.realMax(0), interval.realMax(1), interval.realMin(2));
+		// TOP VERTICES
+		long tbl = m.vertices().add(interval.realMin(0), interval.realMin(1), interval.realMax(2));
+		long tbr = m.vertices().add(interval.realMax(0), interval.realMin(1), interval.realMax(2));
+		long tfl = m.vertices().add(interval.realMin(0), interval.realMax(1), interval.realMax(2));
+		long tfr = m.vertices().add(interval.realMax(0), interval.realMax(1), interval.realMax(2));
+
+		// BOTTOM TRIANGLES
+		m.triangles().add(bbl, bfr, bbr);
+		m.triangles().add(bbl, bfl, bfr);
+		// FRONT TRIANGLES
+		m.triangles().add(tfl, bfr, bfl);
+		m.triangles().add(tfl, tfr, bfr);
+		// TOP TRIANGLES
+		m.triangles().add(tbl, tfr, tfl);
+		m.triangles().add(tbl, tbr, tfr);
+		// BACK TRIANGLES
+		m.triangles().add(tbl, bbl, bbr);
+		m.triangles().add(tbl, tbr, tfr);
+		// LEFT TRIANGLES
+		m.triangles().add(tfl, bfl, bbl);
+		m.triangles().add(tfl, bbl, tbr);
+		// RIGHT TRIANGLES
+		m.triangles().add(tfr, tbr, bbr);
+		m.triangles().add(tfr, bbr, tfr);
+
+		return m;
+	}
+
 	/**
 	 * Copies a mesh into another mesh.
 	 *

src/test/java/net/imglib2/mesh/MeshesTest.java

@@ -28,9 +28,6 @@
  */
 package net.imglib2.mesh;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
-
 import javax.imageio.ImageIO;
 import javax.imageio.ImageReader;
 import java.awt.image.BufferedImage;
@@ -39,11 +36,7 @@
 import java.net.URISyntaxException;
 import java.nio.file.Files;
 import java.nio.file.Paths;
-import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.Iterator;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 
 import gnu.trove.list.array.TLongArrayList;
 import org.apache.commons.math3.geometry.euclidean.threed.Vector3D;
@@ -67,6 +60,8 @@
 import net.imglib2.util.Fraction;
 import net.imglib2.view.RandomAccessibleIntervalCursor;
 
+import static org.junit.Assert.*;
+
 public class MeshesTest
 {
 
@@ -161,6 +156,34 @@ public void testMarchingCubesRealType()
 		assertTrue( !expectedFacets.hasNext() && !actualFacets.hasNext() );
 	}
 
+	@Test
+	public void testBoundingBoxMesh() {
+		final Mesh mesh = new NaiveDoubleMesh();
+		// Create a pyramid between the points
+		long bbl = mesh.vertices().add(0, 0, 0);
+		long bbr = mesh.vertices().add(1, 0, 0);
+		long bfl = mesh.vertices().add(0, 1, 0);
+		long t = mesh.vertices().add(0, 0, 1);
+		mesh.triangles().add(bbl, bfl, bbr);
+		mesh.triangles().add(t, bbr, bfl);
+		mesh.triangles().add(t, bbl, bbr);
+		mesh.triangles().add(t, bfl, bbl);
+
+		// Get the bounding box
+		final Mesh bounding = Meshes.boundingBoxMesh(mesh);
+		// Assert expected points and number of vertices
+		Iterator<Vertex> itr = bounding.vertices().iterator();
+		assertArrayEquals(new double[] {0, 0, 0}, itr.next().positionAsDoubleArray(), 0);
+		assertArrayEquals(new double[] {1, 0, 0}, itr.next().positionAsDoubleArray(), 0);
+		assertArrayEquals(new double[] {0, 1, 0}, itr.next().positionAsDoubleArray(), 0);
+		assertArrayEquals(new double[] {1, 1, 0}, itr.next().positionAsDoubleArray(), 0);
+		assertArrayEquals(new double[] {0, 0, 1}, itr.next().positionAsDoubleArray(), 0);
+		assertArrayEquals(new double[] {1, 0, 1}, itr.next().positionAsDoubleArray(), 0);
+		assertArrayEquals(new double[] {0, 1, 1}, itr.next().positionAsDoubleArray(), 0);
+		assertArrayEquals(new double[] {1, 1, 1}, itr.next().positionAsDoubleArray(), 0);
+		assertFalse(itr.hasNext());
+	}
+
 	private static Mesh createMeshWithNoise()
 	{
 		final Mesh mesh = new NaiveDoubleMesh();