pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / contrib / spatial / src / java / org / apache / lucene / spatial / geometry / shape / LineSegment.java

diff --git a/lucene-java-3.5.0/lucene/contrib/spatial/src/java/org/apache/lucene/spatial/geometry/shape/LineSegment.java b/lucene-java-3.5.0/lucene/contrib/spatial/src/java/org/apache/lucene/spatial/geometry/shape/LineSegment.java
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+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.lucene.spatial.geometry.shape;
+
+
+/**
+ * 2d line segment.
+ *
+ * <p><font color="red"><b>NOTE:</b> This API is still in
+ * flux and might change in incompatible ways in the next
+ * release.</font>
+ */
+public class LineSegment {
+  public final Point2D A = new Point2D();
+  public final Point2D B = new Point2D();
+
+  public LineSegment() {
+    A.set(0, 0);
+    B.set(0, 0);
+  }
+
+  public LineSegment(Point2D p1, Point2D p2) {
+    A.set(p1);
+    B.set(p2);
+  }
+
+  /**
+   * Finds the distance of a specified point from the line segment and the
+   * closest point on the segment to the specified point.
+   * 
+   * @param P
+   *            Test point.
+   * @param closestPt
+   *            (Return) Closest point on the segment to c.
+   * 
+   * @return Returns the distance from P to the closest point on the segment.
+   */
+  public double distance(Point2D P, Point2D /* out */closestPt) {
+    if (closestPt == null)
+      closestPt = new Point2D();
+
+    // Construct vector v (AB) and w (AP)
+    Vector2D v = new Vector2D(A, B);
+    Vector2D w = new Vector2D(A, P);
+
+    // Numerator of the component of w onto v. If <= 0 then A
+    // is the closest point. By separating into the numerator
+    // and denominator of the component we avoid a division unless
+    // it is necessary.
+    double n = w.dot(v);
+    if (n <= 0.0f) {
+      closestPt.set(A);
+      return w.norm();
+    }
+
+    // Get the denominator of the component. If the component >= 1
+    // (d <= n) then point B is the closest point
+    double d = v.dot(v);
+    if (d <= n) {
+      closestPt.set(B);
+      return new Vector2D(B, P).norm();
+    }
+
+    // Closest point is along the segment. The point is the projection of
+    // w onto v.
+    closestPt.set(v.mult(n / d));
+    closestPt.add(A);
+    return new Vector2D(closestPt, P).norm();
+  }
+
+  @Override
+  public int hashCode() {
+    final int prime = 31;
+    int result = 1;
+    result = prime * result + ((A == null) ? 0 : A.hashCode());
+    result = prime * result + ((B == null) ? 0 : B.hashCode());
+    return result;
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj)
+      return true;
+    if (obj == null)
+      return false;
+    if (getClass() != obj.getClass())
+      return false;
+    LineSegment other = (LineSegment) obj;
+    if (A == null) {
+      if (other.A != null)
+        return false;
+    } else if (!A.equals(other.A))
+      return false;
+    if (B == null) {
+      if (other.B != null)
+        return false;
+    } else if (!B.equals(other.B))
+      return false;
+    return true;
+  }
+  
+}