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The OpenTripPlanner multimodal journey planning system

There is a newer version: 2.6.0

package org.opentripplanner.ext.traveltime.geometry;

/**
 * A ZMetric is a metric for some generic TZ value.
 * 
 * By metric here we understand:
 * 

 * Cutting detection on a range, z0 in [Za, Zb] (rely on TZ to be an ordered set)
 * Interpolation on a range, z0 in [Za, Zb].
 * 
 * Cutting detection could be easily implemented using interpolation, but usually interpolating
 * is rather more expansive than cutting detection, so we split the two operations.
 *
 * @author laurent
 */
public interface ZMetric {
  /**
   * Check if the edge [AB] between two samples A and B "intersect" the zz0 plane.
   *
   * @param zA z value for the A sample
   * @param zB z value for the B sample
   * @param z0 z value for the intersecting plane
   * @return 0 if no intersection, -1 or +1 if intersection (depending on which is lower, A or B).
   */
  int cut(TZ zA, TZ zB, TZ z0);

  /**
   * Interpolate a crossing point on an edge [AB].
   *
   * @param zA z value for the A sample
   * @param zB z value for the B sample
   * @param z0 z value for the intersecting plane
   * @return k value between 0 and 1, where the crossing occurs. 0=A, 1=B.
   */
  double interpolate(TZ zA, TZ zB, TZ z0);
}