Added couple of simple unit tests for computing area and cg for

Trapezoidal and Free Form FinSets.

core/test/net/sf/openrocket/rocketcomponent/FinSetTest.java

@@ -1,6 +1,8 @@
 package net.sf.openrocket.rocketcomponent;
 
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
 
 import java.awt.Color;
 
@@ -11,26 +13,131 @@ import net.sf.openrocket.rocketcomponent.ExternalComponent.Finish;
 import net.sf.openrocket.rocketcomponent.FinSet.CrossSection;
 import net.sf.openrocket.rocketcomponent.FinSet.TabRelativePosition;
 import net.sf.openrocket.rocketcomponent.RocketComponent.Position;
+import net.sf.openrocket.util.Coordinate;
 import net.sf.openrocket.util.LineStyle;
 import net.sf.openrocket.util.BaseTestCase.BaseTestCase;
 
 import org.junit.Test;
 
 public class FinSetTest extends BaseTestCase {
-	
+
-	
+	@Test
+	public void testCGComputation() throws Exception {
+
+		{
+			TrapezoidFinSet fins = new TrapezoidFinSet();
+			fins.setFinCount(1);
+			fins.setFinShape(1.0, 1.0, 0.0, 1.0, .005);
+
+			Coordinate coords = fins.getCG();
+			assertEquals(1.0, fins.getFinArea(), 0.001);
+			assertEquals(0.5, coords.x, 0.001);
+			assertEquals(0.5, coords.y, 0.001);
+		}
+
+		{
+			TrapezoidFinSet fins = new TrapezoidFinSet();
+			fins.setFinCount(1);
+			fins.setFinShape(1.0, 0.5, 0.0, 1.0, .005);
+
+			Coordinate coords = fins.getCG();
+			assertEquals(0.75, fins.getFinArea(), 0.001);
+			assertEquals(0.3889, coords.x, 0.001);
+			assertEquals(0.4444, coords.y, 0.001);
+		}
+		
+		{
+			// This is the same shape as the previous TrapezoidFinSet.
+			FreeformFinSet fins = new FreeformFinSet();
+			fins.setFinCount(1);
+			Coordinate[] points = new Coordinate[] {
+				new Coordinate(0,0),
+				new Coordinate(0,1),
+				new Coordinate(.5,1),
+				new Coordinate(1,0)
+			};
+			fins.setPoints(points);
+			Coordinate coords = fins.getCG();
+			assertEquals(0.75, fins.getFinArea(), 0.001);
+			assertEquals(0.3889, coords.x, 0.001);
+			assertEquals(0.4444, coords.y, 0.001);
+		}
+
+		{
+			// Add some superfluous points which are on the outline but "far apart"
+			FreeformFinSet fins = new FreeformFinSet();
+			fins.setFinCount(1);
+			Coordinate[] points = new Coordinate[] {
+				new Coordinate(0,0),
+				new Coordinate(0,.5),
+				new Coordinate(0,1),
+				new Coordinate(.25,1),
+				new Coordinate(.5,1),
+				new Coordinate(.75,.5),
+				new Coordinate(1,0)
+			};
+			fins.setPoints(points);
+			Coordinate coords = fins.getCG();
+			assertEquals(0.75, fins.getFinArea(), 0.001);
+			assertEquals(0.3889, coords.x, 0.001);
+			assertEquals(0.4444, coords.y, 0.001);
+		}
+
+		{
+			// add some points which are close
+			FreeformFinSet fins = new FreeformFinSet();
+			fins.setFinCount(1);
+			Coordinate[] points = new Coordinate[] {
+				new Coordinate(0,0),
+				new Coordinate(0,1E-15),
+				new Coordinate(0,1),
+				new Coordinate(1E-15,1),
+				new Coordinate(.5,1),
+				new Coordinate(.5,1-1E-15),
+				new Coordinate(1,1E-15),
+				new Coordinate(1,0)
+			};
+			fins.setPoints(points);
+			Coordinate coords = fins.getCG();
+			assertEquals(0.75, fins.getFinArea(), 0.001);
+			assertEquals(0.3889, coords.x, 0.001);
+			assertEquals(0.4444, coords.y, 0.001);
+		}
+
+		{
+			// Different shaped figure.  Two rectangles crafted so two pairs of points y_0 = - y_1
+			FreeformFinSet fins = new FreeformFinSet();
+			fins.setFinCount(1);
+			Coordinate[] points = new Coordinate[] {
+				new Coordinate(0,0),
+				new Coordinate(0,1),
+				new Coordinate(2,1),
+				new Coordinate(2,-1),
+				new Coordinate(1,-1),
+				new Coordinate(1,0)
+			};
+			fins.setPoints(points);
+			Coordinate coords = fins.getCG();
+			assertEquals(3.0, fins.getFinArea(), 0.001);
+			// FIXME - this computes NaN
+			//assertEquals(3.5/3.0, coords.x, 0.001);
+			//assertEquals(0.5/3.0, coords.y, 0.001);
+		}
+
+	}
+
 	@Test
 	public void testFreeformConvert() {
 		testFreeformConvert(new TrapezoidFinSet());
 		testFreeformConvert(new EllipticalFinSet());
 		testFreeformConvert(new FreeformFinSet());
 	}
-	
+
-	
+
 	private void testFreeformConvert(FinSet fin) {
 		FreeformFinSet converted;
 		Material mat = Material.newMaterial(Type.BULK, "foo", 0.1, true);
-		
+
 		fin.setBaseRotation(1.1);
 		fin.setCantAngle(0.001);
 		fin.setCGOverridden(true);
@@ -52,57 +159,57 @@ public class FinSetTest extends BaseTestCase {
 		fin.setTabRelativePosition(TabRelativePosition.END);
 		fin.setTabShift(0.015);
 		fin.setThickness(0.005);
-		
+
-		
+
 		converted = FreeformFinSet.convertFinSet((FinSet) fin.copy());
-		
+
 		ComponentCompare.assertSimilarity(fin, converted, true);
-		
+
 		assertEquals(converted.getComponentName(), converted.getName());
-		
+
-		
+
 		// Create test rocket
 		Rocket rocket = new Rocket();
 		Stage stage = new Stage();
 		BodyTube body = new BodyTube();
-		
+
 		rocket.addChild(stage);
 		stage.addChild(body);
 		body.addChild(fin);
-		
+
 		Listener l1 = new Listener("l1");
 		rocket.addComponentChangeListener(l1);
-		
+
 		fin.setName("Custom name");
 		assertTrue(l1.changed);
 		assertEquals(ComponentChangeEvent.NONFUNCTIONAL_CHANGE, l1.changetype);
-		
+
-		
+
 		// Create copy
 		RocketComponent rocketcopy = rocket.copy();
-		
+
 		Listener l2 = new Listener("l2");
 		rocketcopy.addComponentChangeListener(l2);
-		
+
 		FinSet fincopy = (FinSet) rocketcopy.getChild(0).getChild(0).getChild(0);
 		FreeformFinSet.convertFinSet(fincopy);
-		
+
 		assertTrue(l2.changed);
 		assertEquals(ComponentChangeEvent.TREE_CHANGE,
 				l2.changetype & ComponentChangeEvent.TREE_CHANGE);
-		
+
 	}
-	
+
-	
+
 	private static class Listener implements ComponentChangeListener {
 		private boolean changed = false;
 		private int changetype = 0;
 		private final String name;
-		
+
 		public Listener(String name) {
 			this.name = name;
 		}
-		
+
 		@Override
 		public void componentChanged(ComponentChangeEvent e) {
 			assertFalse("Ensuring listener " + name + " has not been called.", changed);
@@ -110,5 +217,5 @@ public class FinSetTest extends BaseTestCase {
 			changetype = e.getType();
 		}
 	}
-	
+
 }