DGP - added DensityType parsing for recovery devices

[debian/openrocket] / src / net / sf / openrocket / file / rocksim / RecoveryDeviceHandler.java

diff --git a/src/net/sf/openrocket/file/rocksim/RecoveryDeviceHandler.java b/src/net/sf/openrocket/file/rocksim/RecoveryDeviceHandler.java
new file mode 100644 (file)
index 0000000..387e29b
--- /dev/null
+++ b/src/net/sf/openrocket/file/rocksim/RecoveryDeviceHandler.java
@@ -0,0 +1,114 @@
+/*
+ * RecoveryDeviceHandler.java
+ */
+package net.sf.openrocket.file.rocksim;
+
+import net.sf.openrocket.aerodynamics.WarningSet;
+import net.sf.openrocket.material.Material;
+import net.sf.openrocket.rocketcomponent.RecoveryDevice;
+import net.sf.openrocket.rocketcomponent.RocketComponent;
+import org.xml.sax.SAXException;
+
+import java.util.HashMap;
+
+/**
+ * A handler specific to streamers and parachutes.  This is done because Rocksim allows any type of material to be
+ * used as a recovery device, which causes oddities with respect to densities.  Density computation is overridden
+ * here to try to correctly compute a material's density in OpenRocket units.
+ *
+ * @param <C>  either a Streamer or Parachute
+ */
+public abstract class RecoveryDeviceHandler<C extends RecoveryDevice> extends PositionDependentHandler<C> {
+
+    /**
+     * The thickness.  Not used by every component, and some component handlers may parse it for their own purposes.
+     */
+    private double thickness = 0d;
+    /**
+     * The Rocksim calculated mass.  Used only when not overridden and when Rocksim says density == 0 (Rocksim bug).
+     */
+    private Double calcMass = 0d;
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public void closeElement(String element, HashMap<String, String> attributes, String content, WarningSet warnings)
+            throws SAXException {
+        super.closeElement(element, attributes, content, warnings);
+
+        try {
+            if ("Thickness".equals(element)) {
+                thickness = Double.parseDouble(content) / RocksimHandler.ROCKSIM_TO_OPENROCKET_LENGTH;
+            }
+            if ("CalcMass".equals(element)) {
+                calcMass = Math.max(0d, Double.parseDouble(content) / RocksimHandler.ROCKSIM_TO_OPENROCKET_MASS);
+            }
+        }
+        catch (NumberFormatException nfe) {
+            warnings.add("Could not convert " + element + " value of " + content + ".  It is expected to be a number.");
+        }
+    }
+
+
+    /**
+     * Compute the density.  Rocksim does strange things with densities.  For some streamer material it's in cubic,
+     * rather than square, units.  In those cases it needs to be converted to an appropriate SURFACE material density.
+     *
+     * @param type       the rocksim density
+     * @param rawDensity the density as specified in the Rocksim design file
+     * @return a value in OpenRocket SURFACE density units
+     */
+    protected double computeDensity(RocksimDensityType type, double rawDensity) {
+
+        double result;
+
+        if (rawDensity > 0d) {
+            //ROCKSIM_SURFACE is a square area density; compute normally
+            //ROCKSIM_LINE is a single length dimension (kg/m) but Rocksim ignores thickness for this type and treats
+            //it like a SURFACE.
+            if (RocksimDensityType.ROCKSIM_SURFACE.equals(type) || RocksimDensityType.ROCKSIM_LINE.equals(type)) {
+                result = rawDensity / RocksimDensityType.ROCKSIM_SURFACE.asOpenRocket();
+            }
+            //ROCKSIM_BULK is a cubic area density; multiple by thickness to make per square area; the result, when
+            //multiplied by the area will then equal Rocksim's computed mass.
+            else {
+                result = (rawDensity / type.asOpenRocket()) * thickness;
+            }
+        }
+        else {
+            result = calcMass / getComponent().getArea();
+            //A Rocksim bug on streamers/parachutes results in a 0 density at times.  When that is detected, try
+            //to compute an approximate density from Rocksim's computed mass.
+            if (RocksimDensityType.ROCKSIM_BULK.equals(type)) {
+                //ROCKSIM_BULK is a cubic area density; multiple by thickness to make per square area
+                result *= thickness;
+            }
+        }
+        return result;
+    }
+
+    /**
+     * Set the relative position onto the component.  This cannot be done directly because setRelativePosition is not
+     * public in all components.
+     *
+     * @param position the OpenRocket position
+     */
+    @Override
+    public void setRelativePosition(RocketComponent.Position position) {
+        getComponent().setRelativePosition(position);
+    }
+
+    /**
+     * Get the required type of material for this component.  This is the OpenRocket type, which does NOT always
+     * correspond to Rocksim.  Some streamer material is defined as BULK in the Rocksim file.  In those cases
+     * it is adjusted in this handler.
+     *
+     * @return SURFACE
+     */
+    @Override
+    public Material.Type getMaterialType() {
+        return Material.Type.SURFACE;
+    }
+
+}