add a test for JME issue #877

jme3-examples/src/main/java/jme3test/bullet/TestIssue877.java

@@ -0,0 +1,148 @@
+/*
+ * Copyright (c) 2018 jMonkeyEngine
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * * 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.
+ *
+ * * Neither the name of 'jMonkeyEngine' 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 OWNER 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 jme3test.bullet;
+
+/**
+ * Test case for JME issue #877: multiple hinges. Based on code submitted by
+ * Daniel Martensson.
+ *
+ * If successful, all pendulums will swing at the same frequency, and all the
+ * free-falling objects will fall straight down.
+ */
+import com.jme3.app.SimpleApplication;
+import com.jme3.bullet.BulletAppState;
+import com.jme3.bullet.collision.shapes.BoxCollisionShape;
+import com.jme3.bullet.collision.shapes.CollisionShape;
+import com.jme3.bullet.control.RigidBodyControl;
+import com.jme3.bullet.joints.HingeJoint;
+import com.jme3.math.Quaternion;
+import com.jme3.math.Vector3f;
+import com.jme3.scene.Node;
+
+public class TestIssue877 extends SimpleApplication {
+
+    BulletAppState bulletAppState = new BulletAppState();
+    int numPendulums = 6;
+    int numFalling = 6;
+    Node pivots[] = new Node[numPendulums];
+    Node bobs[] = new Node[numPendulums];
+    Node falling[] = new Node[numFalling];
+    float timeToNextPrint = 1f; // in seconds
+
+    public static void main(String[] args) {
+        TestIssue877 app = new TestIssue877();
+        app.start();
+    }
+
+    @Override
+    public void simpleInitApp() {
+        flyCam.setEnabled(false);
+        cam.setLocation(new Vector3f(-4.77f, -7.55f, 16.52f));
+        cam.setRotation(new Quaternion(-0.103433f, 0.889420f, 0.368792f, 0.249449f));
+
+        stateManager.attach(bulletAppState);
+        bulletAppState.setDebugEnabled(true);
+
+        float pivotY = 14.6214f;
+        float bobStartY = 3f;
+        float length = pivotY - bobStartY;
+        for (int i = 0; i < numPendulums; i++) {
+            float x = 6f - 2.5f * i;
+            Vector3f pivotLocation = new Vector3f(x, pivotY, 0f);
+            pivots[i] = createTestNode(0f, pivotLocation);
+
+            Vector3f bobLocation = new Vector3f(x, bobStartY, 0f);
+            bobs[i] = createTestNode(1f, bobLocation);
+        }
+
+        for (int i = 0; i < numFalling; i++) {
+            float x = -6f - 2.5f * (i + numPendulums);
+            Vector3f createLocation = new Vector3f(x, bobStartY, 0f);
+            falling[i] = createTestNode(1f, createLocation);
+        }
+
+        for (int i = 0; i < numPendulums; i++) {
+            HingeJoint joint = new HingeJoint(
+                    pivots[i].getControl(RigidBodyControl.class),
+                    bobs[i].getControl(RigidBodyControl.class),
+                    new Vector3f(0f, 0f, 0f),
+                    new Vector3f(length, 0f, 0f),
+                    Vector3f.UNIT_Z.clone(),
+                    Vector3f.UNIT_Z.clone());
+            bulletAppState.getPhysicsSpace().add(joint);
+        }
+    }
+
+    Node createTestNode(float mass, Vector3f location) {
+        float size = 0.1f;
+        Vector3f halfExtents = new Vector3f(size, size, size);
+        CollisionShape shape = new BoxCollisionShape(halfExtents);
+        RigidBodyControl control = new RigidBodyControl(shape, mass);
+        Node node = new Node();
+        node.addControl(control);
+        rootNode.attachChild(node);
+        bulletAppState.getPhysicsSpace().add(node);
+        control.setPhysicsLocation(location);
+
+        return node;
+    }
+
+    @Override
+    public void simpleUpdate(float tpf) {
+        if (timeToNextPrint > 0f) {
+            timeToNextPrint -= tpf;
+            return;
+        }
+
+        if (numFalling > 0) {
+            Vector3f fallingLocation = falling[0].getWorldTranslation();
+            System.out.printf("  falling[0] location(x=%f, z=%f)",
+                    fallingLocation.x, fallingLocation.z);
+            /*
+             * If an object is falling vertically, its X- and Z-coordinates 
+             * should not change.
+             */
+        }
+        if (numPendulums > 0) {
+            Vector3f bobLocation = bobs[0].getWorldTranslation();
+            Vector3f pivotLocation = pivots[0].getWorldTranslation();
+            float distance = bobLocation.distance(pivotLocation);
+            System.out.printf("  bob[0] distance=%f", distance);
+            /*
+             * If the hinge is working properly, the distance from the
+             * pivot to the bob should remain roughly constant.
+             */
+        }
+        System.out.println();
+        timeToNextPrint = 1f;
+    }
+}