committed Doug's Rocksim loader

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

diff --git a/src/net/sf/openrocket/file/rocksim/MassObjectHandler.java b/src/net/sf/openrocket/file/rocksim/MassObjectHandler.java
new file mode 100644 (file)
index 0000000..31ddef7
--- /dev/null
+++ b/src/net/sf/openrocket/file/rocksim/MassObjectHandler.java
@@ -0,0 +1,110 @@
+/*
+ * MassObjectHandler.java
+ */
+package net.sf.openrocket.file.rocksim;
+
+import net.sf.openrocket.aerodynamics.WarningSet;
+import net.sf.openrocket.file.simplesax.ElementHandler;
+import net.sf.openrocket.file.simplesax.PlainTextHandler;
+import net.sf.openrocket.material.Material;
+import net.sf.openrocket.rocketcomponent.MassComponent;
+import net.sf.openrocket.rocketcomponent.RocketComponent;
+import org.xml.sax.SAXException;
+
+import java.util.HashMap;
+
+/**
+ * A SAX handler for Rocksim's MassObject XML type.
+ */
+class MassObjectHandler extends PositionDependentHandler<MassComponent> {
+
+    /** 
+     * The Rocksim Mass length fudge factor.  Rocksim completely exaggerates the length of a mass object to the point
+     * that it looks ridiculous in OpenRocket.  This fudge factor is here merely to get the typical mass object to
+     * render in the OpenRocket UI with it's bounds mostly inside it's parent.  The odd thing about it is that 
+     * Rocksim does not expose the length of a mass object in the UI and actually treats mass objects as point objects -
+     * not 3 or even 2 dimensional.
+     */
+    public static final int MASS_LEN_FUDGE_FACTOR = 100;
+
+    /**
+     * The OpenRocket MassComponent - counterpart to the RS MassObject.
+     */
+    private final MassComponent mass;
+
+    /**
+     * Constructor.
+     *l
+     * @param c the parent component
+     * 
+     * @throws IllegalArgumentException  thrown if <code>c</code> is null
+     */
+    public MassObjectHandler(RocketComponent c) throws IllegalArgumentException {
+        if (c == null) {
+            throw new IllegalArgumentException("The parent component of a mass component may not be null.");
+        }
+        mass = new MassComponent();
+        c.addChild(mass);
+    }
+
+    @Override
+    public ElementHandler openElement(String element, HashMap<String, String> attributes, WarningSet warnings) {
+        return PlainTextHandler.INSTANCE;
+    }
+
+    @Override
+    public void closeElement(String element, HashMap<String, String> attributes, String content, WarningSet warnings)
+            throws SAXException {
+        super.closeElement(element, attributes, content, warnings);
+        try {
+            if ("Len".equals(element)) {
+                mass.setLength(Double.parseDouble(content) / (RocksimHandler.ROCKSIM_TO_OPENROCKET_LENGTH * MASS_LEN_FUDGE_FACTOR));
+            }
+            if ("KnownMass".equals(element)) {
+                mass.setComponentMass(Double.parseDouble(content) / RocksimHandler.ROCKSIM_TO_OPENROCKET_MASS);
+            }
+            if ("KnownCG".equals(element)) {
+                //Setting the CG of the Mass Object to 0 is important because of the different ways that Rocksim and
+                //OpenRocket treat mass objects.  Rocksim treats them as points (even though the data file contains a
+                //length) and because Rocksim sets the CG of the mass object to really be relative to the front of
+                //the parent.  But that value is already assumed in the position and position value for the component.
+                //Thus it needs to be set to 0 to say that the mass object's CG is at the point of the mass object.
+                super.setCG(0); 
+            }
+        }
+        catch (NumberFormatException nfe) {
+            warnings.add("Could not convert " + element + " value of " + content + ".  It is expected to be a number.");
+        }
+    }
+
+    /**
+     * Get the component this handler is working upon.
+     *
+     * @return a component
+     */
+    @Override
+    public MassComponent getComponent() {
+        return mass;
+    }
+
+    /**
+     * 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
+     */
+    public void setRelativePosition(RocketComponent.Position position) {
+        mass.setRelativePosition(position);
+    }
+
+    /**
+     * Get the required type of material for this component.  Does not apply to MassComponents.
+     *
+     * @return BULK
+     */
+    @Override
+    public Material.Type getMaterialType() {
+        return Material.Type.BULK;
+    }
+
+}