Problem with XMLExporter/XMLImporter and objects containing physics nodes

Troubleshooting physics
1

Hello



I’m trying to load a model exported from blender (HottBj), attach some physic to it (jME Physics 2) and export it, so i could use it in game without having to set up physic again (it will be some kind of modeler for my game), but im gettings some errors ( i wrote it already http://www.jmonkeyengine.com/forum/index.php?topic=11898.0 ). If i use some thing like in following piece of code (with some Box)

PhysicsSpace pSpace = PhysicsSpace.create();

      pSpace.setupBinaryClassLoader(BinaryImporter.getInstance());

      

      DynamicPhysicsNode pNode = pSpace.createDynamicNode();

      Box some_box = new Box( “some_box”, new Vector3f(), 5, 0.25f, 5 );

      pNode.attachChild(some_box);

      pNode.generatePhysicsGeometry();



      File phys_file = new File("/home/users/pablo/phys_model.xml");

      try {

         XMLExporter.getInstance().save(pNode, phys_file);

         //Node tmpNode = (Node)XMLImporter.getInstance().load(phys_file);

      } catch (IOException e) {

         e.printStackTrace();

      }

exports works without any exception, but in phys_file.xml i can see many things like (with NaN)

     <MapEntry>

                                 <Key class=‘com.jmex.physics.material.Material’ density=‘0.9’ name=‘ice’ reference_ID=‘com.jmex.physics.material.Material@14982605’>

                                        <contactHandlingDetails>

                                            <MapEntry>

                                                <Value bounce=‘0.2’ class=‘com.jmex.physics.contact.MutableContactInfo’ dampingCoefficient=‘NaN’ minimumBounceVelocity=‘1.0’ mu=‘0.0020’ muOrthogonal=‘NaN’ springConstant=‘NaN’>

                                                    <sufaceMotion class=‘com.jme.math.Vector2f’/>

                                                    <slip class=‘com.jme.math.Vector2f’ x=‘NaN’ y=‘NaN’/>

                                                    <frictionDirection class=‘com.jme.math.Vector3f’ x=‘NaN’ y=‘NaN’ z=‘NaN’/>

                                                </Value>

                                            </MapEntry>

And if i try to load this file with something like in this piece of code

PhysicsSpace pSpace = PhysicsSpace.create();

      pSpace.setupBinaryClassLoader(BinaryImporter.getInstance());

      File phys_file = new File("/home/users/pablo/phys_model.xml");

      try {

         Node tmpNode = (Node)XMLImporter.getInstance().load(phys_file);

      } catch (IOException e) {

         e.printStackTrace();

      }

I will get following exception

java.io.IOException: java.lang.InstantiationException: com.jmex.physics.impl.ode.DynamicPhysicsNodeImpl

   at com.jme.util.export.xml.DOMInputCapsule.readSavable(DOMInputCapsule.java:978)

   at com.jme.util.export.xml.XMLImporter.load(XMLImporter.java:75)

   at com.jme.util.export.xml.XMLImporter.load(XMLImporter.java:119)

   at gProject0.samples.PhysicExportTest.simpleInitGame(PhysicExportTest.java:36)

   at com.jme.app.BaseSimpleGame.initGame(BaseSimpleGame.java:545)

   at com.jme.app.BaseGame.start(BaseGame.java:74)

   at gProject0.samples.PhysicExportTest.main(PhysicExportTest.java:21)

Caused by: java.lang.InstantiationException: com.jmex.physics.impl.ode.DynamicPhysicsNodeImpl

   at java.lang.Class.newInstance0(Class.java:340)

   at java.lang.Class.newInstance(Class.java:308)

   at com.jme.util.export.xml.DOMInputCapsule.readSavableFromCurrentElem(DOMInputCapsule.java:1005)

   at com.jme.util.export.xml.DOMInputCapsule.readSavable(DOMInputCapsule.java:969)

   … 6 more

Where PhysicExportTest.java is my class file. Tests for jME2 and jME Physics 2 works. How can i do it correctly?? I will be grateful for help :slight_smile:



PS:

Sorry for my English.

2

there are no active jmephysics developers.



I guess since DynamicPhysicsNodeImpl has no default constructor, it cannot be exprted/imported?

3
Core-Dump said:

there are no active jmephysics developers.

I guess since DynamicPhysicsNodeImpl has no default constructor, it cannot be exprted/imported?


I'm not looking at the class, so I don't know, but if it has no constructor at all then the implied default constructor will work.  If any non-default contructor is implemented, then the no-param constructor must be implemented too.
4

There could be other problems, but it's pretty obvious that there are bugs with some Savable.write() implementations in the Physics classes.  You need to get the attention of the Physics 2 developers.  Perhaps make a new Topic in the Physics forum here…  or maybe ask a moderator to move this Topic there.

5

If i use BinaryImporter/BinaryExporter all works fine.



Today i updated a jME2 and jME Physics 2 jar’s (build from source) and now i’m getting

INFO: PhysicsNode (null) has been added

java.io.IOException: java.lang.NullPointerException

   at com.jme.util.export.xml.DOMInputCapsule.readSavableArrayList(DOMInputCapsule.java:1143)

   at com.jme.scene.Node.read(Node.java:683)

   at com.jmex.physics.PhysicsNode.read(PhysicsNode.java:633)

   at com.jmex.physics.DynamicPhysicsNode.read(DynamicPhysicsNode.java:254)

   at com.jmex.physics.impl.ode.DynamicPhysicsNodeImpl.read(DynamicPhysicsNodeImpl.java:450)

   at com.jme.util.export.xml.DOMInputCapsule.readSavableFromCurrentElem(DOMInputCapsule.java:986)

   at com.jme.util.export.xml.DOMInputCapsule.readSavable(DOMInputCapsule.java:946)

   at com.jme.util.export.xml.XMLImporter.load(XMLImporter.java:75)

   at com.jme.util.export.xml.XMLImporter.load(XMLImporter.java:119)

   at gProject0.samples.PhysicExportTest.simpleInitGame(PhysicExportTest.java:41)

   at com.jme.app.BaseSimpleGame.initGame(BaseSimpleGame.java:545)

   at com.jme.app.BaseGame.start(BaseGame.java:74)

   at gProject0.samples.PhysicExportTest.main(PhysicExportTest.java:50)

Caused by: java.lang.NullPointerException

   at com.jmex.physics.PhysicsCollisionGeometry.readPhysicsNodeFromInputCapsule(PhysicsCollisionGeometry.java:126)

   at com.jmex.physics.util.binarymodules.BinaryPhysicsBoxModule.load(BinaryPhysicsBoxModule.java:50)

   at com.jme.util.export.binary.BinaryClassLoader.fromName(BinaryClassLoader.java:125)

   at com.jme.util.export.xml.DOMInputCapsule.readSavableFromCurrentElem(DOMInputCapsule.java:981)

   at com.jme.util.export.xml.DOMInputCapsule.readSavableArrayList(DOMInputCapsule.java:1128)

   … 12 more

Where gProject0.samples.PhysicExportTest is my file. Here is a result of exporting using XMLExporter http://wklej.org/id/144354/ (i pasted a piece of it in first post). Thanks :slight_smile: