X-Git-Url: http://gitweb.fperrin.net/?p=GpsPrune.git;a=blobdiff_plain;f=tim%2Fprune%2Fthreedee%2FTerrainPatch.java;fp=tim%2Fprune%2Fthreedee%2FTerrainPatch.java;h=10f0b6ee1c4c1fb3492a20e9537950c5c92d13ba;hp=0000000000000000000000000000000000000000;hb=0a2480df5845e2d7190dfdec9b2653b1609e853d;hpb=2154b1969ac2995cca46546f217f53c066b0b749

diff --git a/tim/prune/threedee/TerrainPatch.java b/tim/prune/threedee/TerrainPatch.java
new file mode 100644
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--- /dev/null
+++ b/tim/prune/threedee/TerrainPatch.java
@@ -0,0 +1,116 @@
+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];
+	}
+}