/*
* WorldEdit, a Minecraft world manipulation toolkit
* Copyright (C) sk89q <http://www.sk89q.com>
* Copyright (C) WorldEdit team and contributors
*
* This program 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 3 of the License, or
* (at your option) any later version.
*
* This program 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 program. If not, see <http://www.gnu.org/licenses/>.
*/
package com.sk89q.worldedit.regions;
import com.sk89q.worldedit.LocalWorld;
import com.sk89q.worldedit.Vector;
import com.sk89q.worldedit.regions.polyhedron.Edge;
import com.sk89q.worldedit.regions.polyhedron.Triangle;
import com.sk89q.worldedit.world.World;
import javax.annotation.Nullable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
import static com.google.common.base.Preconditions.checkNotNull;
public class ConvexPolyhedralRegion extends AbstractRegion {
/**
* Vertices that are contained in the convex hull.
*/
private final Set<Vector> vertices = new LinkedHashSet<Vector>();
/**
* Triangles that form the convex hull.
*/
private final List<Triangle> triangles = new ArrayList<Triangle>();
/**
* Vertices that are coplanar to the first 3 vertices.
*/
private final Set<Vector> vertexBacklog = new LinkedHashSet<Vector>();
/**
* Minimum point of the axis-aligned bounding box.
*/
private Vector minimumPoint;
/**
* Maximum point of the axis-aligned bounding box.
*/
private Vector maximumPoint;
/**
* Accumulator for the barycenter of the polyhedron. Divide by vertices.size() to get the actual center.
*/
private Vector centerAccum = Vector.ZERO;
/**
* The last triangle that caused a {@link #contains(Vector)} to classify a point as "outside". Used for optimization.
*/
private Triangle lastTriangle;
/**
* Constructs an empty mesh, containing no vertices or triangles.
*
* @param world the world
*/
public ConvexPolyhedralRegion(@Nullable World world) {
super(world);
}
/**
* @deprecated cast {@code world} to {@link World}
*/
@Deprecated
public ConvexPolyhedralRegion(LocalWorld world) {
super(world);
}
/**
* Constructs an independent copy of the given region.
*
* @param region the region to copy
*/
public ConvexPolyhedralRegion(ConvexPolyhedralRegion region) {
this(region.world);
vertices.addAll(region.vertices);
triangles.addAll(region.triangles);
vertexBacklog.addAll(region.vertexBacklog);
minimumPoint = region.minimumPoint;
maximumPoint = region.maximumPoint;
centerAccum = region.centerAccum;
lastTriangle = region.lastTriangle;
}
/**
* Clears the region, removing all vertices and triangles.
*/
public void clear() {
vertices.clear();
triangles.clear();
vertexBacklog.clear();
minimumPoint = null;
maximumPoint = null;
centerAccum = Vector.ZERO;
lastTriangle = null;
}
/**
* Add a vertex to the region.
*
* @param vertex the vertex
* @return true, if something changed.
*/
public boolean addVertex(Vector vertex) {
checkNotNull(vertex);
lastTriangle = null; // Probably not necessary
if (vertices.contains(vertex)) {
return false;
}
if (vertices.size() == 3) {
if (vertexBacklog.contains(vertex)) {
return false;
}
if (containsRaw(vertex)) {
return vertexBacklog.add(vertex);
}
}
vertices.add(vertex);
centerAccum = centerAccum.add(vertex);
if (minimumPoint == null) {
minimumPoint = maximumPoint = vertex;
} else {
minimumPoint = Vector.getMinimum(minimumPoint, vertex);
maximumPoint = Vector.getMaximum(maximumPoint, vertex);
}
switch (vertices.size()) {
case 0:
case 1:
case 2:
// Incomplete, can't make a mesh yet
return true;
case 3:
// Generate minimal mesh to start from
final Vector[] v = vertices.toArray(new Vector[vertices.size()]);
triangles.add((new Triangle(v[0], v[1], v[2])));
triangles.add((new Triangle(v[0], v[2], v[1])));
return true;
}
// Look for triangles that face the vertex and remove them
final Set<Edge> borderEdges = new LinkedHashSet<Edge>();
for (Iterator<Triangle> it = triangles.iterator(); it.hasNext(); ) {
final Triangle triangle = it.next();
// If the triangle can't be seen, it's not relevant
if (!triangle.above(vertex)) {
continue;
}
// Remove the triangle from the mesh
it.remove();
// ...and remember its edges
for (int i = 0; i < 3; ++i) {
final Edge edge = triangle.getEdge(i);
if (borderEdges.remove(edge)) {
continue;
}
borderEdges.add(edge);
}
}
// Add triangles between the remembered edges and the new vertex.
for (Edge edge : borderEdges) {
triangles.add(edge.createTriangle(vertex));
}
if (!vertexBacklog.isEmpty()) {
// Remove the new vertex
vertices.remove(vertex);
// Clone, clear and work through the backlog
final List<Vector> vertexBacklog2 = new ArrayList<Vector>(vertexBacklog);
vertexBacklog.clear();
for (Vector vertex2 : vertexBacklog2) {
addVertex(vertex2);
}
// Re-add the new vertex after the backlog.
vertices.add(vertex);
}
return true;
}
public boolean isDefined() {
return !triangles.isEmpty();
}
@Override
public Vector getMinimumPoint() {
return minimumPoint;
}
@Override
public Vector getMaximumPoint() {
return maximumPoint;
}
@Override
public Vector getCenter() {
return centerAccum.divide(vertices.size());
}
@Override
public void expand(Vector... changes) throws RegionOperationException {
}
@Override
public void contract(Vector... changes) throws RegionOperationException {
}
@Override
public void shift(Vector change) throws RegionOperationException {
shiftCollection(vertices, change);
shiftCollection(vertexBacklog, change);
for (int i = 0; i < triangles.size(); ++i) {
final Triangle triangle = triangles.get(i);
final Vector v0 = change.add(triangle.getVertex(0));
final Vector v1 = change.add(triangle.getVertex(1));
final Vector v2 = change.add(triangle.getVertex(2));
triangles.set(i, new Triangle(v0, v1, v2));
}
minimumPoint = change.add(minimumPoint);
maximumPoint = change.add(maximumPoint);
centerAccum = change.multiply(vertices.size()).add(centerAccum);
lastTriangle = null;
}
private static void shiftCollection(Collection<Vector> collection, Vector change) {
final List<Vector> tmp = new ArrayList<Vector>(collection);
collection.clear();
for (Vector vertex : tmp) {
collection.add(change.add(vertex));
}
}
@Override
public boolean contains(Vector position) {
if (!isDefined()) {
return false;
}
final int x = position.getBlockX();
final int y = position.getBlockY();
final int z = position.getBlockZ();
final Vector min = getMinimumPoint();
final Vector max = getMaximumPoint();
if (x < min.getBlockX()) return false;
if (x > max.getBlockX()) return false;
if (y < min.getBlockY()) return false;
if (y > max.getBlockY()) return false;
if (z < min.getBlockZ()) return false;
if (z > max.getBlockZ()) return false;
return containsRaw(position);
}
private boolean containsRaw(Vector pt) {
if (lastTriangle != null && lastTriangle.above(pt)) {
return false;
}
for (Triangle triangle : triangles) {
if (lastTriangle == triangle) {
continue;
}
if (triangle.above(pt)) {
lastTriangle = triangle;
return false;
}
}
return true;
}
public Collection<Vector> getVertices() {
if (vertexBacklog.isEmpty()) {
return vertices;
}
final List<Vector> ret = new ArrayList<Vector>(vertices);
ret.addAll(vertexBacklog);
return ret;
}
public Collection<Triangle> getTriangles() {
return triangles;
}
@Override
public AbstractRegion clone() {
return new ConvexPolyhedralRegion(this);
}
}