Moved source into separate src directory due to popular request

[GpsPrune.git] / src / tim / prune / data / GradientCalculator.java

diff --git a/src/tim/prune/data/GradientCalculator.java b/src/tim/prune/data/GradientCalculator.java
new file mode 100644 (file)
index 0000000..04846e7
--- /dev/null
+++ b/src/tim/prune/data/GradientCalculator.java
@@ -0,0 +1,56 @@
+package tim.prune.data;
+
+/**
+ * Abstract class to hold static calculation functions
+ * for gradient (like glide slope)
+ */
+public abstract class GradientCalculator
+{
+       /**
+        * Calculate the gradient value of the track at the specified index
+        * @param inTrack track object
+        * @param inIndex index of point to calculate gradient for
+        * @param inValue object in which to place result of calculation
+        */
+       public static void calculateGradient(Track inTrack, int inIndex, SpeedValue inValue)
+       {
+               if (inValue != null)
+               {
+                       inValue.setInvalid();
+               }
+               if (inTrack == null || inIndex < 0 || inValue == null)
+               {
+                       System.err.println("Cannot calculate gradient for index " + inIndex);
+                       return;
+               }
+
+               // If no altitude or it's a waypoint then no gradient either
+               DataPoint point = inTrack.getPoint(inIndex);
+               if (point == null || !point.hasAltitude() || point.isWaypoint()) {
+                       return;
+               }
+
+               // If the point has horizontal and vertical speeds already then just use those
+               if (point.hasHSpeed() && point.hasVSpeed()) {
+                       inValue.setValue(point.getVSpeed().getValueInMetresPerSec() / point.getHSpeed().getValueInMetresPerSec());
+               }
+               else if (!point.getSegmentStart())
+               {
+                       // Use the previous track point and the next track point
+                       DataPoint p = inTrack.getPreviousTrackPoint(inIndex-1);
+                       DataPoint q = inTrack.getNextTrackPoint(inIndex+1);
+                       if (p != null && q != null && !q.getSegmentStart()
+                               && p.hasAltitude() && q.hasAltitude())
+                       {
+                               final double horizRads = DataPoint.calculateRadiansBetween(p, point) +
+                                       DataPoint.calculateRadiansBetween(point, q);
+                               final double horizDist = Distance.convertRadiansToDistance(horizRads, UnitSetLibrary.UNITS_METRES);
+                               final double heightDiff = q.getAltitude().getMetricValue() - p.getAltitude().getMetricValue();
+                               // Get gradient in radians
+                               final double gradient = Math.atan2(heightDiff, horizDist);
+                               inValue.setValue(gradient);
+                       }
+               }
+               // otherwise, just leave value as invalid
+       }
+}