ConvexPolytope and HyperPlane affine transforms in n dimensions.

Author: tpietzsch

src/main/java/net/imglib2/algorithm/kdtree/ConvexPolytope.java

@@ -39,7 +39,7 @@
 import java.util.Collection;
 
 import net.imglib2.AbstractEuclideanSpace;
-import net.imglib2.realtransform.AffineTransform3D;
+import net.imglib2.realtransform.AffineGet;
 import net.imglib2.util.LinAlgHelpers;
 
 public class ConvexPolytope extends AbstractEuclideanSpace
@@ -63,27 +63,29 @@ public ConvexPolytope( final HyperPlane... hyperplanes )
 	}
 
 	/**
-	 * Apply an {@link AffineTransform3D} to a 3D {@link ConvexPolytope}.
+	 * Apply an {@link AffineGet affine transformation} to a {@link HyperPlane}.
 	 *
 	 * @param polytope
-	 *            a 3D polytope.
+	 *            a polytope.
 	 * @param transform
 	 *            affine transformation to apply to the polytope.
 	 * @return the transformed polytope.
 	 */
-	public static ConvexPolytope transform( final ConvexPolytope polytope, final AffineTransform3D transform )
+	public static ConvexPolytope transform( final ConvexPolytope polytope, final AffineGet transform )
 	{
-		assert polytope.numDimensions() == 3;
+		assert polytope.numDimensions() == transform.numDimensions();
 
-		final double[] O = new double[ 3 ];
-		final double[] tO = new double[ 3 ];
-		final double[] tN = new double[ 3 ];
-		final double[][] m = new double[3][3];
-		for ( int r = 0; r < 3; ++r )
-			for ( int c = 0; c < 3; ++c )
+		final int n = transform.numDimensions();
+
+		final double[] O = new double[ n ];
+		final double[] tO = new double[ n ];
+		final double[] tN = new double[ n ];
+		final double[][] m = new double[n][n];
+		for ( int r = 0; r < n; ++r )
+			for ( int c = 0; c < n; ++c )
 				m[r][c] = transform.inverse().get( c, r );
 
-		final ArrayList< HyperPlane > transformedPlanes = new ArrayList< HyperPlane >();
+		final ArrayList< HyperPlane > transformedPlanes = new ArrayList<>();
 		for ( final HyperPlane plane : polytope.getHyperplanes() )
 		{
 			LinAlgHelpers.scale( plane.getNormal(), plane.getDistance(), O );

src/main/java/net/imglib2/algorithm/kdtree/HyperPlane.java

@@ -35,7 +35,7 @@
 package net.imglib2.algorithm.kdtree;
 
 import net.imglib2.AbstractEuclideanSpace;
-import net.imglib2.realtransform.AffineTransform3D;
+import net.imglib2.realtransform.AffineGet;
 import net.imglib2.util.LinAlgHelpers;
 
 public class HyperPlane extends AbstractEuclideanSpace
@@ -72,28 +72,30 @@ public double getDistance()
 	}
 
 	/**
-	 * Apply an {@link AffineTransform3D} to a 3D {@link HyperPlane}.
+	 * Apply an {@link AffineGet affine transformation} to a {@link HyperPlane}.
 	 *
 	 * @param plane
-	 *            a 3D plane.
+	 *            a plane.
 	 * @param transform
 	 *            affine transformation to apply to the plane.
 	 * @return the transformed plane.
 	 */
-	public static HyperPlane transform( final HyperPlane plane, final AffineTransform3D transform )
+	public static HyperPlane transform( final HyperPlane plane, final AffineGet transform )
 	{
-		assert plane.numDimensions() == 3;
+		assert plane.numDimensions() == transform.numDimensions();
 
-		final double[] O = new double[ 3 ];
-		final double[] tO = new double[ 3 ];
+		final int n = transform.numDimensions();
+
+		final double[] O = new double[ n ];
+		final double[] tO = new double[ n ];
 		LinAlgHelpers.scale( plane.getNormal(), plane.getDistance(), O );
 		transform.apply( O, tO );
 
-		final double[][] m = new double[ 3 ][ 3 ];
-		for ( int r = 0; r < 3; ++r )
-			for ( int c = 0; c < 3; ++c )
+		final double[][] m = new double[ n ][ n ];
+		for ( int r = 0; r < n; ++r )
+			for ( int c = 0; c < n; ++c )
 				m[ r ][ c ] = transform.inverse().get( c, r );
-		final double[] tN = new double[ 3 ];
+		final double[] tN = new double[ n ];
 		LinAlgHelpers.mult( m, plane.getNormal(), tN );
 		LinAlgHelpers.normalize( tN );
 		final double td = LinAlgHelpers.dot( tN, tO );