Fix RockSim fin tab import issue

core/src/net/sf/openrocket/file/rocksim/importt/FinSetHandler.java

@@ -281,8 +281,9 @@ class FinSetHandler extends AbstractElementHandler {
 		//Create the fin set and correct for overrides and actual material densities
 		FinSet finSet = asOpenRocket(warnings);
 
-		if (component instanceof Transition && shapeCode == 0)
+		if (component instanceof Transition && shapeCode == 0) {
 			finSet = FreeformFinSet.convertFinSet(finSet);
+		}
 
 		finSet.setAppearance(appearanceBuilder.getAppearance());
 
@@ -316,18 +317,18 @@ class FinSetHandler extends AbstractElementHandler {
 		FinSet result;
 
 		if (shapeCode == 0) {
-			//Trapezoidal
+			// Trapezoidal
 			result = new TrapezoidFinSet();
 			((TrapezoidFinSet) result).setFinShape(rootChord, tipChord, sweepDistance, semiSpan, thickness);
 		}
 		else if (shapeCode == 1) {
-			//Elliptical
+			// Elliptical
 			result = new EllipticalFinSet();
 			((EllipticalFinSet) result).setHeight(semiSpan);
 			((EllipticalFinSet) result).setLength(rootChord);
 		}
 		else if (shapeCode == 2) {
-
+			// Freeform
 			result = new FreeformFinSet();
 			((FreeformFinSet) result).setPoints(toCoordinates(pointList, warnings));
 
@@ -338,16 +339,25 @@ class FinSetHandler extends AbstractElementHandler {
 		result.setThickness(thickness);
 		result.setName(name);
 		result.setFinCount(finCount);
-		result.setFinish(finish);
-		//All TTW tabs in Rocksim are relative to the front of the fin.
-		result.setTabOffsetMethod( AxialMethod.TOP);
-		result.setTabHeight(tabDepth);
-		result.setTabLength(tabLength);
-		result.setTabOffset(taboffset);
-		result.setBaseRotation(radialAngle);
-		result.setCrossSection(convertTipShapeCode(tipShapeCode));
 		result.setAxialMethod(axialMethod);
 		result.setAxialOffset(location);
+		result.setBaseRotation(radialAngle);
+		result.setCrossSection(convertTipShapeCode(tipShapeCode));
+		result.setFinish(finish);
+		result.setTabOffsetMethod(AxialMethod.TOP);
+		result.setTabOffset(taboffset);
+		result.setTabLength(tabLength);
+		//All TTW tabs in Rocksim are relative to the front of the fin, so set an offset if the parent's fore radius is larger than the aft radius.
+		Double radiusFront = result.getParentFrontRadius(component);
+		Double radiusTrailing = result.getParentTrailingRadius(component);
+		if (radiusFront == null) {
+			radiusFront = 0d;
+		}
+		if (radiusTrailing == null) {
+			radiusTrailing = 0d;
+		}
+		double tabDepthOffset = Math.max(radiusFront - radiusTrailing, 0);
+		result.setTabHeight(tabDepth - tabDepthOffset);
 
 		return result;
 

core/src/net/sf/openrocket/rocketcomponent/FinSet.java

@@ -437,18 +437,60 @@ public abstract class FinSet extends ExternalComponent implements AxialPositiona
 	 * @return maximum tab height value
 	 */
 	public double getMaxTabHeight() {
-		// check tab height 
-		if (null != getParent() ){
+		Double radiusFront = getParentFrontRadius();
+		Double radiusTrailing = getParentTrailingRadius();
+		if (radiusFront != null && radiusTrailing != null) {
+			return MathUtil.min(radiusFront, radiusTrailing);
+		}
+		return Double.MAX_VALUE;
+	}
+
+	/**
+	 * Returns the radius of the parent at the front of the fin, or null if no parent is present.
+	 * @param parent the fin's parent component
+	 */
+	public Double getParentFrontRadius(RocketComponent parent) {
+		if (parent instanceof SymmetricComponent) {
 			final Coordinate finFront = this.getFinFront();
 
 			// pulls the parent-body radius at the fin-tab reference point.
 			final double xLead = this.getTabFrontEdge();
-			final double xTrail = this.getTabTrailingEdge();
-			
-			final SymmetricComponent sym = (SymmetricComponent)this.parent;
-			return MathUtil.min(sym.getRadius(finFront.x + xLead), sym.getRadius(finFront.x + xTrail));
+
+			final SymmetricComponent sym = (SymmetricComponent) parent;
+			return sym.getRadius(finFront.x + xLead);
 		}
-		return Double.MAX_VALUE;
+		return null;
+	}
+
+	/**
+	 * Returns the radius of the parent at the front of the fin, or null if no parent is present.
+	 */
+	public Double getParentFrontRadius() {
+		return getParentFrontRadius(getParent());
+	}
+
+	/**
+	 * Returns the radius of the parent at the trailing edge of the fin, or null if no parent is present.
+	 * @param parent the fin's parent component
+	 */
+	public Double getParentTrailingRadius(RocketComponent parent) {
+		if (parent instanceof SymmetricComponent) {
+			final Coordinate finFront = this.getFinFront();
+
+			// pulls the parent-body radius at the fin-tab reference point.
+			final double xTrail = this.getTabTrailingEdge();
+
+			final SymmetricComponent sym = (SymmetricComponent) parent;
+			return sym.getRadius(finFront.x + xTrail);
+		}
+		return null;
+	}
+
+	/**
+	 * Returns the radius of the parent at the trailing edge of the fin, or null if no parent is present.
+	 */
+	public Double getParentTrailingRadius() {
+		return getParentTrailingRadius(getParent());
 	}
 	
 	///////////  Calculation methods  //////////