Another question related to rotations.  I am planning to use Interact2D.reproject2D3D(Camera camera, FrameBuffer buffer, int x, int y, float z) for interacting with the world via the mouse.  I assume the returned SimpleVector is in Camera space, so I would need to apply the camera's rotations (inverted I assume) and translations to it to get a SimpleVector in world space.  Translations are a simple matter of addition, but what methods do I use for rotations?  I'm guessing I would start with this:

Matrix m = myCamera.getBack().cloneMatrix().invert3x3();
Then what method do I use to apply this matrix to the SimpleVector?

Thanks for the help, BTW.  I know I am asking questions that have been asked before.  I just have trouble finding things in the forums occasionally.

I am sure this question has been answered before, but I am having trouble locating a previous thread about it.  I am generating a terrain which is made up of a grid of squares.  Each square consists of two polygons and four vertices:

(1)---------(3)
 | \              |
 |     \          |
 |         \      |
 |             \  |
(2)---------(0)

(the numbers represent the index of each vertex).

Each square in the terrain has its own GridVertexController (which extends GenericVertexController and implements IVertexController).  The GridVertexController class has four SimpleVectors:
    SimpleVector vertex0, vertex1, vertex2, vertex3;
My program changes these four SimpleVectors to represent the new values for the square's vertices.

In the apply() method, I update the getDestinationMesh() array, and then attempt to update the getDestinationNormals() array:

    public void apply()
    {
        SimpleVector dstVertex[] = getDestinationMesh();
        SimpleVector dstNormal[] = getDestinationNormals();
        SimpleVector A, B, C, D;
       
        dstVertex[0].set( vertex0 );
        dstVertex[1].set( vertex1 );
        dstVertex[2].set( vertex2 );
        dstVertex[3].set( vertex3 );
       
        A = vertex1.calcSub( vertex2 );
        B = vertex0.calcSub( vertex2 );
        C = A.calcCross( B ).normalize();
        dstNormal[2].set( C );
       
        A = vertex0.calcSub( vertex3 );
        B = vertex1.calcSub( vertex3 );
        D = A.calcCross( B ).normalize();
        dstNormal[3].set( D );
       
        D.add( C );
        D = D.normalize();
        dstNormal[0].set( D );
        dstNormal[1].set( D );
    }

The vertices are changed correctly, but there seems to be a problem in the algorithm I'm using to calculate the normals, because lighting on the terrain is not correct.  For example, if I generate a flat terrain on the x/z plane with a light source directly overhead, the terrain still appears dark.

I noticed that returned vectors for the Camera's default orientation are:

getDirection() returns: (0, 0, 1)
getUpVector() returns: (0, 1, 0)

This should mean the camera is facing into the screen and upside down (since -y is "up" in jPCT).  I am not sure if this is a bug or not, but I thought I would bring it up just in case.  It seems possible that the returned y-coordinate for the camera's up-vector is signed incorrectly.  Reason I say that is because when converting the returned values for direction and up into OpenAL coordinates, sounds are playing backwards (i.e. coordinates for an Object3D to the left create sources to the right when the listener's orientation is synced with the camera).  This is what one would expect if the listener were facing the same direction but upside down in relation to the camera.  Of course the most likely cause for this odd behavior is a bug in my code and not a bug in jPCT, but it does seem possible that the camera's actual default up-vector is really (0,-1,0) and the method Camera.getUpVector() is somehow returning an incorrectly signed value for y.

My wife's birthday is in a couple of weeks (May 3).  She likes personalized things like home-made cards, crafts, etc.  She prefers gifts that you have to spend a little time to make, rather than taking the easy way out and buying her something.  So I decided to make her sort of a 3D "E-Card" using jPCT.  (She never reads these forums, so it's safe to talk here )  I'm thinking a 3D animation of a guy and a girl who embrace, music in the background, and a message popping up.  I've already finished the man character and am almost done with the woman character.  I am using photos of my wife and me to texture them.  They don't look a lot like us, but it is an acceptable approximation.  I'll post my progress here, as well as the finished applet (after her birthday, of course, so she sees it first).  Any ideas are welcome, although I may not be able to implement them since I have a pretty tight deadline for this project.

This question is not about a particular problem, but more for some general advice.  I've gone through the tutorials in Autodesk 3DS Max for modeling biped humanoids and animating them, and I believe I now have a pretty good grasp on how to model and animate characters from within the Autodesk program.  My question now is, what is the next step?  How do I take this new knowledge and begin animating a 3D character in a jPCT program?  I'd like to start with something simple like a walking animation or waving or something like that.  I know that a few of you have character animation experience.  Do you happen to have any good pointers for someone like me who is just starting out?  Thanks in advance!

Could anyone direct me to a good guide (or three) for learning how to model 3D humanoid characters in 3D Studio Max?  I am a pretty good sketch artest, but 3D modeling is a whole 'nother beast.  My initial attempts have been disasterous! 

Hey, I was wondering if there is a method in Object3D that gets called from a child object when it's parent gets translated.

I want to bind to an object to know when it gets moved.  The way I was thinking of doing this, is to create a class that extends Object3D and registering it as a child to the object in question.  Then, I would just need a way to be tipped of that a translation has taken place, and then figure out what that translation is ( I could use getTranslation() for the later, right? )

I am having a little trouble getting my applet to run in SAMPLINGMODE_HARDWARE_ONLY.
The Sun Java Console shows:
Java version is: 1.6.0_03
-> support for BufferedImage
Version helper for 1.2+ initialized!
-> using BufferedImage
Software renderer (OpenGL mode) initialized
java.lang.NoClassDefFoundError: org/lwjgl/opengl/Display
at com.threed.jpct.GLHelper.findMode(Unknown Source)
at com.threed.jpct.GLHelper.init(Unknown Source)
at com.threed.jpct.GLRenderer.init(Unknown Source)
at com.threed.jpct.FrameBuffer.enableRenderer(Unknown Source)
at com.threed.jpct.FrameBuffer.enableRenderer(Unknown Source)
at com.threed.jpct.FrameBuffer.enableRenderer(Unknown Source)
at jPCTGears.init(jPCTGears.java:48)
at sun.applet.AppletPanel.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

Here is the code in question:
    // Initialize all components of the applet
    @Override
    public void init()
    {
        // sign the applet up to receive mouse messages:
        addMouseListener( this );
        addMouseMotionListener( this );
       
        world = new World();  // create a new world
       
        World.setDefaultThread(Thread.currentThread());

        // create a new buffer to draw on:
        buffer = new FrameBuffer( width, height, FrameBuffer.SAMPLINGMODE_HARDWARE_ONLY );
        buffer.enableRenderer( IRenderer.RENDERER_OPENGL );
        buffer.disableRenderer( IRenderer.RENDERER_SOFTWARE );

        // load some 3D objects and make sure they have the correct orientation:
        redGear = loadMeshFile( "RedGear.3ds" );
        redGear.rotateY( (float)Math.PI / 2.0f );
        redGear.rotateMesh();
        redGear.setRotationMatrix( new Matrix() );
        redGear.setOrigin( new SimpleVector( 0, 0, 0 ) );
        redGear.build();
        greenGear = loadMeshFile( "GreenGear.3ds" );
        greenGear.rotateY( (float)Math.PI / 2.0f );
        greenGear.rotateZ( 0.35f );
        greenGear.rotateMesh();
        greenGear.setRotationMatrix( new Matrix() );
        greenGear.setOrigin( new SimpleVector( -145.0f, 0, 0 ) );
        greenGear.build();
        blueGear = loadMeshFile( "BlueGear.3ds" );
        blueGear.rotateY( (float)Math.PI / 2.0f );
        blueGear.rotateZ( 0.40f );
        blueGear.rotateMesh();
        blueGear.setRotationMatrix( new Matrix() );
        blueGear.setOrigin( new SimpleVector( 0, 135.0f, 0 ) );
        blueGear.build();

        // Set up a pivot point for the entire gear assembly:
        //assemblyPivot = new Object3D(1);
        assemblyPivot = Object3D.createDummyObj();
        assemblyPivot.setOrigin( new SimpleVector( 0, 0, 0 ) );
        // Make the gears children to assemblyPivot.
        // Translations and rotations to assemblyPivot
        // will affect the entire gear assembly:
        assemblyPivot.addChild( redGear );
        assemblyPivot.addChild( greenGear );
        assemblyPivot.addChild( blueGear );
               
        // add the objects our world:
        world.addObject( redGear );
        world.addObject( greenGear );
        world.addObject( blueGear );
        world.buildAllObjects();
       
        lookAt( redGear );  // make sure the camera is facing towards the object
        letThereBeLight();  // create light sources for the scene
    }

The applet only works when I use SAMPLINGMODE_NORMAL and RENDERER_SOFTWARE.  I am sure it is something simple I am doing incorrectly.  I am just having a little trouble figuring out what.