sascha@360: package de.intevation.gnv.math;
sascha@360:
sascha@361: import com.vividsolutions.jts.geom.Coordinate;
sascha@360:
sascha@779: import java.util.Iterator;
sascha@360: import java.util.List;
sascha@360: import java.util.NoSuchElementException;
sascha@360:
sascha@360: /**
sascha@805: * Given a list of line segments instances of this class are able
sascha@805: * to span a metric system between a start and an end point
sascha@805: * represented as scalar values to 2D coordinate on the
sascha@805: * course of the segments.
sascha@805: *
sascha@798: * @author <a href="mailto:sascha.teichmann@intevation.de">Sascha L. Teichmann</a>
sascha@360: */
sascha@360: public class LinearToMap
sascha@360: {
sascha@805: /**
sascha@805: * Represents a segment of the line string.
sascha@805: */
sascha@360: public static final class Range {
sascha@360: private Range next;
sascha@360:
sascha@360: private double from;
sascha@360: private double to;
sascha@360: private double b;
sascha@360:
sascha@361: private Coordinate p1;
sascha@361: private Coordinate p2;
sascha@360:
sascha@360: private Interpolator interpolator;
sascha@360:
sascha@805: /**
sascha@805: * Default constructor.
sascha@805: */
sascha@360: public Range() {
sascha@360: }
sascha@360:
sascha@805: /**
sascha@805: * Constructor to create a segment that maps
sascha@805: * a coordinate pair to two scalar values.
sascha@805: * Interpolations inside this segment are done with
sascha@805: * a given interpolator.
sascha@805: * @param from Start point of the segment.
sascha@805: * @param to End point of the segment.
sascha@805: * @param interpolator The interpolator.
sascha@805: * @param p1 The scalar value mapped to the start point.
sascha@805: * @param p2 The scalar value mappend to the end point.
sascha@805: */
sascha@360: public Range(
sascha@778: double from,
sascha@360: double to,
sascha@360: Interpolator interpolator,
sascha@361: Coordinate p1,
sascha@361: Coordinate p2
sascha@360: ) {
sascha@360: this.from = from;
sascha@360: this.to = to;
sascha@360: this.interpolator = interpolator;
sascha@360: this.p1 = p1;
sascha@360: this.p2 = p2;
sascha@360:
sascha@360: b = from == to
sascha@360: ? 0d
sascha@360: : 1.0d/(to - from);
sascha@360: }
sascha@360:
sascha@805: /**
sascha@805: * Interpolated a coordinate on the segment given a scalar value
sascha@805: * between the start and end point of the range.
sascha@805: * @param x The scalar value.
sascha@805: * @param v The interpolated value is stored here.
sascha@805: */
sascha@361: public void eval(double x, Coordinate v) {
sascha@360: interpolator.interpolate((x - from)*b, v);
sascha@360: }
sascha@360:
sascha@805: /**
sascha@805: * Checks if a given value is inside this segment.
sascha@805: * @param x The value to test
sascha@805: * @return true if inside, else false.
sascha@805: */
sascha@360: public boolean inside(double x) {
sascha@360: return x >= from && x <= to;
sascha@360: }
sascha@360:
sascha@805: /**
sascha@805: * Returns the start point of this segment.
sascha@805: * @return The start point.
sascha@805: */
sascha@361: public Coordinate startPoint() {
sascha@360: return p1;
sascha@360: }
sascha@360:
sascha@805: /**
sascha@805: * Return the end point of this segment.
sascha@805: * @return The end point.
sascha@805: */
sascha@361: public Coordinate endPoint() {
sascha@360: return p2;
sascha@360: }
sascha@360: } // class Range
sascha@360:
sascha@805: /**
sascha@805: * The head of the internal range list.
sascha@805: */
sascha@360: protected Range head;
sascha@805:
sascha@805: /**
sascha@805: * The last accessed segment. Used to accelerate
sascha@805: * the access of the right segment.
sascha@805: */
sascha@360: protected Range last;
sascha@360:
sascha@805: /**
sascha@805: * Default constructor.
sascha@805: */
sascha@360: public LinearToMap() {
sascha@360: }
sascha@360:
sascha@805: /**
sascha@805: * Constructor to create a LinearToMap that maps
sascha@805: * given scalar values to coordinates of a given
sascha@805: * list of line segments.
sascha@805: * @param path The list of line segments.
sascha@805: * @param from The start value mapped to the start point
sascha@805: * of the first line segment.
sascha@805: * @param to The end value mapped to the end point of
sascha@805: * the last line segment.
sascha@805: * @param metrics The metric used to span the 2D space.
sascha@805: */
sascha@360: public LinearToMap(
sascha@778: List<? extends Coordinate> path,
sascha@778: double from,
sascha@361: double to,
sascha@361: Metrics metrics
sascha@360: ) {
sascha@360: double diagramLength = Math.abs(to - from);
sascha@360:
sascha@360: double worldLength = length(path, metrics);
sascha@360:
sascha@360: double rangeStart = from;
sascha@360:
sascha@360: Range last = null;
sascha@360:
sascha@360: for (int i = 1, N = path.size(); i < N; ++i) {
sascha@361: Coordinate p1 = path.get(i-1);
sascha@361: Coordinate p2 = path.get(i);
sascha@360: double segmentLength = metrics.distance(p1, p2);
sascha@360:
sascha@360: double relativeLength = segmentLength / worldLength;
sascha@360:
sascha@360: double rangeLength = diagramLength * relativeLength;
sascha@360:
sascha@360: double rangeEnd = rangeStart + rangeLength;
sascha@360:
sascha@360: Range range = new Range(
sascha@360: rangeStart, rangeEnd,
sascha@360: metrics.getInterpolator(p1, p2),
sascha@360: p1, p2);
sascha@360:
sascha@360: if (last == null) {
sascha@360: last = head = range;
sascha@360: }
sascha@360: else {
sascha@360: last.next = range;
sascha@360: last = range;
sascha@360: }
sascha@360: rangeStart = rangeEnd;
sascha@360: }
sascha@360: }
sascha@360:
sascha@805: /**
sascha@805: * Returns a segment on which a given value is found.
sascha@805: * @param diagramX The value.
sascha@805: * @return The segment or null if no matching segment was found.
sascha@805: */
sascha@360: protected Range locateRange(double diagramX) {
sascha@360:
sascha@360: if (last != null && last.inside(diagramX)) {
sascha@360: return last;
sascha@360: }
sascha@360:
sascha@360: Range current = head;
sascha@360: while (current != null) {
sascha@360: if (current.inside(diagramX)) {
sascha@360: return last = current;
sascha@360: }
sascha@360: current = current.next;
sascha@360: }
sascha@360:
sascha@360: return null;
sascha@360: }
sascha@360:
sascha@805: /**
sascha@805: * Interpolates a coordinate at a given scalar position.
sascha@805: * @param diagramX The scalar position.
sascha@805: * @param v The interpolated coordinate is stored here.
sascha@805: * @return true if the scalar position is inside the
sascha@805: * spanned range of the line string, else false.
sascha@805: */
sascha@361: public boolean locate(double diagramX, Coordinate v) {
sascha@360: Range range = locateRange(diagramX);
sascha@360: if (range == null) {
sascha@360: return false;
sascha@360: }
sascha@360: range.eval(diagramX, v);
sascha@360: return true;
sascha@360: }
sascha@360:
sascha@805: /**
sascha@805: * Returns the length of a given line string using
sascha@805: * a given metric.
sascha@805: * @param path The line string.
sascha@805: * @param metrics The used metric.
sascha@805: * @return The length of the line string.
sascha@805: */
sascha@361: public static double length(
sascha@778: List<? extends Coordinate> path,
sascha@361: Metrics metrics
sascha@361: ) {
sascha@360: double sum = 0d;
sascha@360: for (int i = path.size()-1; i >= 1; --i) {
sascha@361: Coordinate p1 = path.get(i);
sascha@361: Coordinate p2 = path.get(i-1);
sascha@360: sum += metrics.distance(p1, p2);
sascha@360: }
sascha@360: return sum;
sascha@360: }
sascha@360:
sascha@805: /**
sascha@805: * Return the number of segments in this map.
sascha@805: * @return the number of segments.
sascha@805: */
sascha@360: public int numRanges() {
sascha@360: int count = 0;
sascha@360: Range current = head;
sascha@360: while (current != null) {
sascha@360: ++count;
sascha@360: current = current.next;
sascha@360: }
sascha@360: return count;
sascha@360: }
sascha@360:
sascha@805: /**
sascha@805: * Returns an iterator over all segments of this map.
sascha@805: * @return The iterator.
sascha@805: */
sascha@360: public Iterator ranges() {
sascha@360: return new Iterator() {
sascha@360:
sascha@360: Range current = head;
sascha@360:
sascha@360: public boolean hasNext() {
sascha@360: return current != null;
sascha@360: }
sascha@360:
sascha@360: public Object next() {
sascha@360: if (!hasNext()) {
sascha@360: throw new NoSuchElementException();
sascha@360: }
sascha@360: Range x = current;
sascha@360: current = current.next;
sascha@360: return x;
sascha@360: }
sascha@360:
sascha@360: public void remove() {
sascha@360: throw new UnsupportedOperationException();
sascha@360: }
sascha@360: };
sascha@360: }
sascha@360: }
sascha@798: // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :