Created a path for ballistic motion and an associated test. Yay for

physics.


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@3610 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/jme/sprite/BallisticPath.java

@@ -0,0 +1,68 @@
+//
+// $Id$
+//
+// Narya library - tools for developing networked games
+// Copyright (C) 2002-2005 Three Rings Design, Inc., All Rights Reserved
+// http://www.threerings.net/code/narya/
+//
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.threerings.jme.sprite;
+
+import com.jme.math.Vector3f;
+
+/**
+ * Moves a sprite ballistically.
+ */
+public class BallisticPath extends Path
+{
+    /**
+     * Moves the supplied sprite from the starting coordinate (which will
+     * be modified) using the starting velocity, under the specified
+     * acceleration.
+     */
+    public BallisticPath (Sprite sprite, Vector3f start, Vector3f velocity,
+                          Vector3f accel, float duration)
+    {
+        super(sprite);
+        _curpos = start;
+        _velocity = velocity;
+        _accel = accel;
+        _duration = duration;
+    }
+
+    // documentation inherited
+    public void update (float time)
+    {
+        // adjust the position
+        _velocity.mult(time, _temp);
+        _curpos.addLocal(_temp);
+        _sprite.setLocalTranslation(_curpos);
+
+        // check to see if we're done
+        _accum += time;
+        if (_accum >= _duration) {
+            _sprite.pathCompleted();
+        } else {
+            // adjust our velocity due to acceleration
+            _accel.mult(time, _temp);
+            _velocity.addLocal(_temp);
+        }
+    }
+
+    protected Vector3f _curpos, _velocity, _accel;
+    protected float _duration, _accum;
+    protected Vector3f _temp = new Vector3f(0, 0, 0);
+}

tests/src/java/com/threerings/jme/sprite/PathTest.java

@@ -0,0 +1,81 @@
+//
+// $Id$
+
+package com.threerings.jme.sprite;
+
+import java.util.logging.Level;
+
+import com.jme.math.FastMath;
+import com.jme.math.Matrix3f;
+import com.jme.math.Quaternion;
+import com.jme.math.Vector3f;
+import com.jme.util.LoggingSystem;
+import com.jme.scene.shape.Box;
+import com.jme.scene.shape.Sphere;
+
+import com.threerings.jme.JmeApp;
+
+/**
+ * Used for testing paths.
+ */
+public class PathTest extends JmeApp
+{
+    protected void initRoot ()
+    {
+        super.initRoot();
+
+        // set up the camera
+        Vector3f loc = new Vector3f(250, -600, 0);
+        _camera.setLocation(loc);
+        Matrix3f rotm = new Matrix3f();
+        rotm.fromAngleAxis(-FastMath.PI/2, _camera.getLeft());
+        rotm.multLocal(_camera.getDirection());
+        rotm.multLocal(_camera.getUp());
+        rotm.multLocal(_camera.getLeft());
+        _camera.update();
+
+        Box box = new Box("box", new Vector3f(-1, -1, -1),
+                          new Vector3f(1, 1, 1));
+        _geom.attachChild(box);
+
+        Box box2 = new Box("box2", new Vector3f(-1, -1, -1),
+                           new Vector3f(1, 1, 1));
+        box2.setLocalTranslation(new Vector3f(560, 0, 0));
+        _geom.attachChild(box2);
+
+        Sphere ball = new Sphere("ball", 10, 10, 1);
+        Sprite shot = new Sprite();
+        shot.attachChild(ball);
+        _geom.attachChild(shot);
+
+        Vector3f start = new Vector3f(0, 0, 0);
+
+        // start with the "cannon" pointed along the x axis
+        Vector3f vel = new Vector3f(1, 0, 0);
+        // rotate it up (around the y axis) the necessary elevation
+        Quaternion rot = new Quaternion();
+        rot.fromAngleAxis(-FastMath.PI*27.35f/180f, new Vector3f(0, 1, 0));
+//         rot.fromAngleAxis(-FastMath.PI*62.65f/180f, new Vector3f(0, 1, 0));
+        rot.multLocal(vel);
+        // give the cannon a "muzzle velocity"
+        vel.multLocal(82f);
+
+        System.out.println("Start: " + start);
+        System.out.println("Velocity: " + vel);
+
+        shot.move(new BallisticPath(shot, start, vel, GRAVITY, 7.7f));
+//        shot.move(new BallisticPath(shot, start, vel, GRAVITY, 15f));
+    }
+
+    public static void main (String[] args)
+    {
+        LoggingSystem.getLogger().setLevel(Level.OFF);
+        PathTest test = new PathTest();
+        if (!test.init()) {
+            System.exit(-1);
+        }
+        test.run();
+    }
+
+    protected static final Vector3f GRAVITY = new Vector3f(0, 0, -9.8f);
+}