--- /dev/null
+package tim.prune.threedee;
+
+public class TerrainPatch
+{
+ private int _gridSize = 0;
+ private double[] _altitudes = null;
+ private int[] _tempDists = null;
+
+ /**
+ * Constructor
+ * @param inGridSize size of grid edge
+ */
+ public TerrainPatch(int inGridSize)
+ {
+ _gridSize = inGridSize;
+ int numNodes = inGridSize * inGridSize;
+ _altitudes = new double[numNodes];
+ _tempDists = new int[numNodes];
+ }
+
+ /**
+ * Add an altitude interpolation to the mix
+ * @param inPointIndex point index to array
+ * @param inValue altitude value in metres
+ * @param inGapIndex index of point within gap, from 1 to gapLength-1
+ * @param inGapLength length of gap, minimum 2
+ */
+ public void addAltitude(int inPointIndex, double inValue, int inGapIndex, int inGapLength)
+ {
+ final int dist = Math.min(inGapIndex, inGapLength-inGapIndex);
+ if (_tempDists[inPointIndex] == 0)
+ {
+ if (_altitudes[inPointIndex] > 0.0) System.err.println("Altitude shouldn't be 0 if dist is 0!");
+ // first point
+ _altitudes[inPointIndex] = inValue;
+ _tempDists[inPointIndex] = dist;
+ }
+ else
+ {
+ // second point
+ final double firstValue = _altitudes[inPointIndex];
+ final int firstDist = _tempDists[inPointIndex];
+ final double firstWeight = dist * 1.0 / (dist + firstDist);
+ final double secondWeight= firstDist * 1.0 / (dist + firstDist);
+ _altitudes[inPointIndex] = firstWeight * firstValue + secondWeight * inValue;
+ _tempDists[inPointIndex] = 0;
+ }
+ }
+
+ /**
+ * Smooth the patch to reduce blockiness
+ */
+ public void smooth()
+ {
+ double[] altCopy = new double[_altitudes.length];
+ for (int i=0; i<_gridSize; i++)
+ {
+ for (int j=0; j<_gridSize; j++)
+ {
+ if (hasAltitude(i, j) && hasAltitude(i-1, j) && hasAltitude(i+1, j)
+ && hasAltitude(i, j+1) && hasAltitude(i-1, j+1) && hasAltitude(i+1, j+1)
+ && hasAltitude(i, j-1) && hasAltitude(i-1, j-1) && hasAltitude(i+1, j-1))
+ {
+ // got a 3x3 square, can do a blur
+ double alt = (getAltitude(i, j) + getAltitude(i-1, j) + getAltitude(i+1, j)
+ + getAltitude(i, j+1) + getAltitude(i-1, j+1) + getAltitude(i+1, j+1)
+ + getAltitude(i, j-1) + getAltitude(i-1, j-1) + getAltitude(i+1, j-1)) / 9.0;
+ altCopy[i * _gridSize + j] = alt;
+ }
+ }
+ }
+ // Copy results back
+ for (int k=0; k<altCopy.length; k++)
+ {
+ if (altCopy[k] > 0.0)
+ {
+ _altitudes[k] = altCopy[k];
+ }
+ }
+ }
+
+ /**
+ * @param inI first index
+ * @param inJ second index
+ * @return true if there is an altitude in the patch in this position
+ */
+ private boolean hasAltitude(int inI, int inJ)
+ {
+ return inI >= 0 && inI < _gridSize && inJ >= 0 && inJ < _gridSize
+ && _altitudes[inI * _gridSize + inJ] > 0.0;
+ }
+
+ /**
+ * @param inI first index
+ * @param inJ second index
+ * @return true if there is an altitude in the patch in this position
+ */
+ private double getAltitude(int inI, int inJ)
+ {
+ if (inI >= 0 && inI < _gridSize && inJ >= 0 && inJ < _gridSize)
+ {
+ return _altitudes[inI * _gridSize + inJ];
+ }
+ return 0.0;
+ }
+
+ /**
+ * @param inPointIndex point index
+ * @return altitude value
+ */
+ public double getAltitude(int inPointIndex)
+ {
+ if (_tempDists[inPointIndex] != 0) System.err.println("Dists should be 0 if we're retrieving!");
+ return _altitudes[inPointIndex];
+ }
+}