/*
* __ .__ .__ ._____.
* _/ |_ _______ __|__| ____ | | |__\_ |__ ______
* \ __\/ _ \ \/ / |/ ___\| | | || __ \ / ___/
* | | ( <_> > <| \ \___| |_| || \_\ \\___ \
* |__| \____/__/\_ \__|\___ >____/__||___ /____ >
* \/ \/ \/ \/
*
* Copyright (c) 2006-2011 Karsten Schmidt
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* http://creativecommons.org/licenses/LGPL/2.1/
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
*/
package toxi.geom.mesh.subdiv;
import java.util.ArrayList;
import java.util.List;
import toxi.geom.Vec3D;
import toxi.geom.mesh.WingedEdge;
/**
* This subdivision strategy splits an edge in three equal parts using two split
* points at 33% and 66% of the edge. The split points themselves are being
* displaced, however, in the direction of the vector going from the configured
* reference point (often the mesh centroid is used) towards each split point.
* The displacement amount is configurable as fraction of the original edge
* length. So given that:
*
* <pre>
* S = edge split point
* R = reference point
* l = edge length
* a = displacement amplification factor
*
* S' = S + (S-R) * a * l
* </pre>
*/
public class DualDisplacementSubdivision extends SubdivisionStrategy {
public Vec3D centroid;
public float ampA, ampB;
public DualDisplacementSubdivision(Vec3D centroid, float ampA, float ampB) {
this.centroid = centroid;
this.ampA = ampA;
this.ampB = ampB;
}
public List<Vec3D> computeSplitPoints(WingedEdge edge) {
List<Vec3D> mid = new ArrayList<Vec3D>(2);
float len = edge.getLength();
Vec3D a = edge.a.interpolateTo(edge.b, 0.3333f);
a.addSelf(a.sub(centroid).normalizeTo(ampA * len));
Vec3D b = edge.a.interpolateTo(edge.b, 0.6666f);
b.addSelf(b.sub(centroid).normalizeTo(ampB * len));
mid.add(a);
mid.add(b);
return mid;
}
}