From 7f14ad18c7f925d5d850fa8963fbecb229f757e8 Mon Sep 17 00:00:00 2001
From: Stephen Gold <sgold@sonic.net>
Date: Fri, 7 Sep 2018 15:28:48 -0700
Subject: [PATCH] test case and fix for issue #883

---
 .../java/com/jme3/bullet/BulletAppState.java  | 30 +++++--
 .../java/jme3test/bullet/TestIssue883.java    | 87 +++++++++++++++++++
 2 files changed, 108 insertions(+), 9 deletions(-)
 create mode 100644 jme3-examples/src/main/java/jme3test/bullet/TestIssue883.java

diff --git a/jme3-bullet/src/common/java/com/jme3/bullet/BulletAppState.java b/jme3-bullet/src/common/java/com/jme3/bullet/BulletAppState.java
index addea7a5e..55b614904 100644
--- a/jme3-bullet/src/common/java/com/jme3/bullet/BulletAppState.java
+++ b/jme3-bullet/src/common/java/com/jme3/bullet/BulletAppState.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2009-2012 jMonkeyEngine
+ * Copyright (c) 2009-2018 jMonkeyEngine
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -150,20 +150,32 @@ public class BulletAppState implements AppState, PhysicsTickListener {
     }
 
     /**
-     * The physics system is started automatically on attaching, if you want to
-     * start it before for some reason, you can use this method.
+     * Allocate a physics space and start physics.
+     * <p>
+     * Physics starts automatically after the state is attached. To start it
+     * sooner, invoke this method.
      */
     public void startPhysics() {
         if (initialized) {
             return;
         }
-        //start physics thread(pool)
-        if (threadingType == ThreadingType.PARALLEL) {
-            startPhysicsOnExecutor();
-        } else {
-            pSpace = new PhysicsSpace(worldMin, worldMax, broadphaseType);
+
+        switch (threadingType) {
+            case PARALLEL:
+                boolean success = startPhysicsOnExecutor();
+                assert success;
+                assert pSpace != null;
+                break;
+
+            case SEQUENTIAL:
+                pSpace = new PhysicsSpace(worldMin, worldMax, broadphaseType);
+                pSpace.addTickListener(this);
+                break;
+
+            default:
+                throw new IllegalStateException(threadingType.toString());
         }
-        pSpace.addTickListener(this);
+
         initialized = true;
     }
 
diff --git a/jme3-examples/src/main/java/jme3test/bullet/TestIssue883.java b/jme3-examples/src/main/java/jme3test/bullet/TestIssue883.java
new file mode 100644
index 000000000..f4e794fea
--- /dev/null
+++ b/jme3-examples/src/main/java/jme3test/bullet/TestIssue883.java
@@ -0,0 +1,87 @@
+/*
+ * 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 #883: extra physicsTicks in ThreadingType.PARALLEL.
+ *
+ * If successful, physics time and frame time will advance at the same rate.
+ */
+import com.jme3.app.SimpleApplication;
+import com.jme3.bullet.BulletAppState;
+import com.jme3.bullet.PhysicsSpace;
+
+public class TestIssue883 extends SimpleApplication {
+
+    boolean firstPrint = true;
+    float timeToNextPrint = 1f; // in seconds
+    double frameTime; // in seconds
+    double physicsTime; // in seconds
+
+    public static void main(String[] args) {
+        TestIssue883 app = new TestIssue883();
+        app.start();
+    }
+
+    @Override
+    public void simpleInitApp() {
+
+        BulletAppState bulletAppState = new BulletAppState() {
+            @Override
+            public void physicsTick(PhysicsSpace space, float timeStep) {
+                physicsTime += timeStep;
+            }
+        };
+        bulletAppState.setThreadingType(BulletAppState.ThreadingType.PARALLEL);
+        stateManager.attach(bulletAppState);
+    }
+
+    @Override
+    public void simpleUpdate(float tpf) {
+        frameTime += tpf;
+
+        if (timeToNextPrint > 0f) {
+            timeToNextPrint -= tpf;
+            return;
+        }
+
+        if (firstPrint) { // synchronize
+            frameTime = 0.;
+            physicsTime = 0.;
+            firstPrint = false;
+        }
+
+        System.out.printf(" frameTime= %s   physicsTime= %s%n",
+                frameTime, physicsTime);
+        timeToNextPrint = 1f;
+    }
+}