3 files changed, 90 insertions, 0 deletions
diff --git a/src/tesseract/TesseractUI.java b/src/tesseract/TesseractUI.java
index b2b010e..de765f7 100644
--- a/src/tesseract/TesseractUI.java
+++ b/src/tesseract/TesseractUI.java
@@ -28,6 +28,8 @@ import tesseract.forces.CircularXY;
 import tesseract.forces.CircularXZ;
 import tesseract.forces.Force;
 import tesseract.forces.Gravity;
+import tesseract.forces.LinearOrigin;
+import tesseract.forces.QuadradicOrigin;
 import tesseract.menuitems.ChainLinkMenuItem;
 import tesseract.menuitems.DonutMenuItem;
 import tesseract.menuitems.EllipsoidMenuItem;
@@ -230,6 +232,44 @@ public class TesseractUI extends JFrame {
 			});
 		forcesMenu.add(circularXY);
 		
+		final JMenuItem originLinear = new JCheckBoxMenuItem("Linear proportional force towards the origin", false);
+		originLinear.addActionListener(new ActionListener() {
+				private Force me;
+				
+				// Constructor 
+				{
+					me = new LinearOrigin(.5f);
+				}
+				
+				public void actionPerformed(ActionEvent e) {
+					if (((JCheckBoxMenuItem) e.getSource()).isSelected()) {
+						myWorld.addForce(me);
+					} else {
+						myWorld.removeForce(me);
+					}
+				}			
+			});
+		forcesMenu.add(originLinear);
+		
+		final JMenuItem originQuadradic = new JCheckBoxMenuItem("Quadratic proportional force towards the origin", false);
+		originQuadradic.addActionListener(new ActionListener() {
+				private Force me;
+				
+				// Constructor 
+				{
+					me = new QuadradicOrigin(.5f);
+				}
+				
+				public void actionPerformed(ActionEvent e) {
+					if (((JCheckBoxMenuItem) e.getSource()).isSelected()) {
+						myWorld.addForce(me);
+					} else {
+						myWorld.removeForce(me);
+					}
+				}			
+			});
+		forcesMenu.add(originQuadradic);
+		
 		menuBar.add(forcesMenu);
 		
 		// Add reset Simulator menu item
diff --git a/src/tesseract/forces/LinearOrigin.java b/src/tesseract/forces/LinearOrigin.java
new file mode 100644
index 0000000..ca4651d
--- /dev/null
+++ b/src/tesseract/forces/LinearOrigin.java
@@ -0,0 +1,25 @@
+package tesseract.forces;
+
+import javax.vecmath.Vector3f;
+
+import tesseract.objects.PhysicalObject;
+
+@SuppressWarnings("restriction")
+public class LinearOrigin extends Force {
+	private float scale;
+	
+	public LinearOrigin(float scale) {
+		this.scale = scale;
+	}
+
+	public Vector3f calculateForce(PhysicalObject obj) {
+		Vector3f position = obj.getPosition();
+		Vector3f force = new Vector3f(-position.x, -position.y, -position.z);
+		force.scale(scale);
+		return force;
+	}
+	
+	public String toString() {
+		return "Linear proportional force towards the origin";
+	}
+}
diff --git a/src/tesseract/forces/QuadradicOrigin.java b/src/tesseract/forces/QuadradicOrigin.java
new file mode 100644
index 0000000..81cbea2
--- /dev/null
+++ b/src/tesseract/forces/QuadradicOrigin.java
@@ -0,0 +1,25 @@
+package tesseract.forces;
+
+import javax.vecmath.Vector3f;
+
+import tesseract.objects.PhysicalObject;
+
+@SuppressWarnings("restriction")
+public class QuadradicOrigin extends Force {
+	private float scale;
+	
+	public QuadradicOrigin(float scale) {
+		this.scale = scale;
+	}
+
+	public Vector3f calculateForce(PhysicalObject obj) {
+		Vector3f position = obj.getPosition();
+		Vector3f force = new Vector3f(-position.x * Math.abs(position.x), -position.y * Math.abs(position.y), -position.z * Math.abs(position.z));
+		force.scale(scale);
+		return force;
+	}
+	
+	public String toString() {
+		return "Quadratic proportional force towards the origin";
+	}
+}