diff --git a/tests/src/java/com/threerings/geom/WhichSideViz.java b/tests/src/java/com/threerings/geom/WhichSideViz.java
new file mode 100644
index 000000000..0879b286b
--- /dev/null
+++ b/tests/src/java/com/threerings/geom/WhichSideViz.java
@@ -0,0 +1,95 @@
+//
+// $Id: WhichSideViz.java,v 1.1 2002/06/28 01:29:32 mdb Exp $
+
+package com.threerings.geom;
+
+import java.awt.BorderLayout;
+import java.awt.Color;
+import java.awt.Graphics;
+import java.awt.Point;
+
+import java.awt.event.MouseEvent;
+import java.awt.event.MouseMotionListener;
+
+import javax.swing.JFrame;
+import javax.swing.JPanel;
+
+import com.samskivert.swing.util.SwingUtil;
+
+/**
+ * Renders the nearest point on a line just for kicks.
+ */
+public class WhichSideViz extends JPanel
+    implements MouseMotionListener
+{
+    public WhichSideViz ()
+    {
+        addMouseMotionListener(this);
+    }
+
+    public void doLayout ()
+    {
+        super.doLayout();
+        _center = new Point(getWidth() / 2, getHeight() / 2);
+    }
+
+    public void paintComponent (Graphics g)
+    {
+        super.paintComponent(g);
+
+        int dx = (int)Math.round(Math.cos(_theta) * 200);
+        int dy = (int)Math.round(Math.sin(_theta) * 200);
+
+        g.setColor(Color.blue);
+        g.drawLine(_center.x, _center.y, _center.x + dx, _center.y + dy);
+        g.setColor(Color.white);
+        g.drawLine(_center.x, _center.y, _center.x - dx, _center.y - dy);
+
+        int nx = (int)Math.round(1000*Math.cos(_theta + Math.PI/2)),
+            ny = (int)Math.round(1000*Math.sin(_theta + Math.PI/2));
+        g.setColor(Color.pink);
+        g.drawLine(_center.x, _center.y, nx, ny);
+
+        // figure out which side the line is on
+        String str;
+        int side = GeomUtil.whichSide(_center, _theta, _spot);
+        if (side > 0) {
+            str = "R";
+        } else if (side < 0) {
+            str = "L";
+        } else {
+            str = "O";
+        }
+
+        g.setColor(Color.black);
+        g.drawString(str, _spot.x, _spot.y);
+
+        // kick theta along for the next tick because it's fun
+//         _theta += (float)(Math.PI/100);
+    }
+
+    public void mouseDragged (MouseEvent event)
+    {
+    }
+
+    public void mouseMoved (MouseEvent event)
+    {
+        _spot.x = event.getX();
+        _spot.y = event.getY();
+        repaint();
+    }
+
+    public static void main (String[] args)
+    {
+        JFrame frame = new JFrame();
+        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+        frame.getContentPane().add(new WhichSideViz(), BorderLayout.CENTER);
+        frame.setSize(300, 300);
+        SwingUtil.centerWindow(frame);
+        frame.show();
+    }
+
+    protected float _theta = (float)(3 * Math.PI / 5);
+    protected Point _center;
+    protected Point _spot = new Point();
+}