apps: add HelloDeactivation

apps/src/main/java/com/github/stephengold/vsport/tutorial/HelloDeactivation.java

@@ -0,0 +1,164 @@
+/*
+ Copyright (c) 2020-2023, Stephen Gold
+ All rights reserved.
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are met:
+
+ 1. Redistributions of source code must retain the above copyright notice, this
+    list of conditions and the following disclaimer.
+
+ 2. Redistributions in binary form must reproduce the above copyright notice,
+    this list of conditions and the following disclaimer in the documentation
+    and/or other materials provided with the distribution.
+
+ 3. Neither the name of the copyright holder nor the names of its
+    contributors may be used to endorse or promote products derived from
+    this software without specific prior written permission.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package com.github.stephengold.vsport.tutorial;
+
+import com.github.stephengold.vsport.physics.BasePhysicsApp;
+import com.jme3.bullet.PhysicsSpace;
+import com.jme3.bullet.PhysicsTickListener;
+import com.jme3.bullet.collision.shapes.BoxCollisionShape;
+import com.jme3.bullet.collision.shapes.CollisionShape;
+import com.jme3.bullet.collision.shapes.SphereCollisionShape;
+import com.jme3.bullet.objects.PhysicsBody;
+import com.jme3.bullet.objects.PhysicsRigidBody;
+import com.jme3.math.Vector3f;
+
+/**
+ * A simple example of rigid-body deactivation.
+ * <p>
+ * Builds upon HelloStaticBody.
+ *
+ * @author Stephen Gold [email protected]
+ */
+public class HelloDeactivation
+        extends BasePhysicsApp<PhysicsSpace>
+        implements PhysicsTickListener {
+    // *************************************************************************
+    // fields
+
+    private static PhysicsRigidBody dynamicCube;
+    private static PhysicsRigidBody supportCube;
+    // *************************************************************************
+    // new methods exposed
+
+    /**
+     * Main entry point for the HelloDeactivation application.
+     *
+     * @param arguments array of command-line arguments (not null)
+     */
+    public static void main(String[] arguments) {
+        HelloDeactivation application = new HelloDeactivation();
+        application.start();
+    }
+    // *************************************************************************
+    // BasePhysicsApp methods
+
+    /**
+     * Create the PhysicsSpace. Invoked once during initialization.
+     *
+     * @return a new instance
+     */
+    @Override
+    public PhysicsSpace createSpace() {
+        PhysicsSpace result
+                = new PhysicsSpace(PhysicsSpace.BroadphaseType.DBVT);
+
+        // To enable the callbacks, register the application as a tick listener.
+        result.addTickListener(this);
+
+        return result;
+    }
+
+    /**
+     * Populate the PhysicsSpace. Invoked once during initialization.
+     */
+    @Override
+    public void populateSpace() {
+        // Create a dynamic cube and add it to the space.
+        float boxHalfExtent = 0.5f;
+        CollisionShape smallCubeShape = new BoxCollisionShape(boxHalfExtent);
+        float boxMass = 1f;
+        dynamicCube = new PhysicsRigidBody(smallCubeShape, boxMass);
+        physicsSpace.addCollisionObject(dynamicCube);
+        dynamicCube.setPhysicsLocation(new Vector3f(0f, 4f, 0f));
+
+        // Create 2 static bodies and add them to the space...
+        // The top body serves as a temporary support.
+        float cubeHalfExtent = 1f;
+        CollisionShape largeCubeShape = new BoxCollisionShape(cubeHalfExtent);
+        supportCube = new PhysicsRigidBody(
+                largeCubeShape, PhysicsBody.massForStatic);
+        physicsSpace.addCollisionObject(supportCube);
+
+        // The bottom body serves as a visual reference point.
+        float ballRadius = 0.5f;
+        CollisionShape ballShape = new SphereCollisionShape(ballRadius);
+        PhysicsRigidBody bottomBody = new PhysicsRigidBody(
+                ballShape, PhysicsBody.massForStatic);
+        bottomBody.setPhysicsLocation(new Vector3f(0f, -2f, 0f));
+        physicsSpace.addCollisionObject(bottomBody);
+
+        // Visualize the physics objects.
+        visualizeShape(dynamicCube);
+        visualizeShape(supportCube);
+        visualizeShape(bottomBody);
+    }
+
+    /**
+     * Advance the physics simulation by the specified amount. Invoked during
+     * each update.
+     *
+     * @param wallClockSeconds the elapsed wall-clock time since the previous
+     * invocation of {@code updatePhysics} (in seconds, &ge;0)
+     */
+    @Override
+    public void updatePhysics(float wallClockSeconds) {
+        physicsSpace.update(wallClockSeconds);
+    }
+    // *************************************************************************
+    // PhysicsTickListener methods
+
+    /**
+     * Callback from Bullet, invoked just before each simulation step.
+     *
+     * @param space the space that's about to be stepped (not null)
+     * @param timeStep the time per simulation step (in seconds, &ge;0)
+     */
+    @Override
+    public void prePhysicsTick(PhysicsSpace space, float timeStep) {
+        // do nothing
+    }
+
+    /**
+     * Callback from Bullet, invoked just after each simulation step.
+     *
+     * @param space the space that was just stepped (not null)
+     * @param timeStep the time per simulation step (in seconds, &ge;0)
+     */
+    @Override
+    public void physicsTick(PhysicsSpace space, float timeStep) {
+        /*
+         * Once the dynamic cube gets deactivated,
+         * remove the support cube from the PhysicsSpace.
+         */
+        if (!dynamicCube.isActive() && space.contains(supportCube)) {
+            space.removeCollisionObject(supportCube);
+        }
+    }
+}