Fun with geometry.

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@1535 542714f4-19e9-0310-aa3c-eee0fc999fb1
2002-06-25 00:22:44 +00:00
parent c467da448a
commit c6878853e5
2 changed files with 133 additions and 0 deletions
@@ -0,0 +1,80 @@
+//
+// $Id: NearestViz.java,v 1.1 2002/06/25 00:22:44 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;
+
+/**
+ * Renders the nearest point on a line just for kicks.
+ */
+public class NearestViz extends JPanel
+    implements MouseMotionListener
+{
+    public NearestViz ()
+    {
+        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.drawLine(_center.x, _center.y, _center.x - dx, _center.y + dy);
+
+        // locate the point nearest the spot
+        Point p2 = new Point(_center.x + dx, _center.y - dy);
+        Point n = new Point();
+        GeomUtil.nearestToLine(_center, p2, _spot, n);
+
+        g.setColor(Color.red);
+        g.drawOval(n.x - 4, n.y - 4, 8, 8);
+
+        // 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 NearestViz(), BorderLayout.CENTER);
+        frame.setSize(300, 300);
+        frame.show();
+    }
+
+    protected float _theta = (float)(3 * Math.PI / 5);
+    protected Point _center;
+    protected Point _spot = new Point();
+}