The rotation pivot is what I was looking for, thank you. Now I use a dummy object to rotate around the other object and place and align the camera to this object.

May I ask why the camera, object3d and light does not have a common interface? If they had a common interface, all could be used the same way with the same code.

Thank you for the quick response, I will keep the inverse matrix in mind, it seems to be realy important. But sadly I don't get it to work. I think it would be great if it would be possible to set the up-orientation as a second parameter to the lookAt - method like it is possible in direct x, what do you think?

I integrated the code you showed me, and it works for the x axis, but funnily not for the other axes. But ok, that may be just my lack of understanding.

I tried to understand my problem from the root, and a lot of it is just my own stupidity. So instead of rotating the camera I tried a simpler task: rotating an object around another. But even this is something I don't get to work. Please have a look at the following code:


     // pointer is a little pyramid that should rotate around an object
     SimpleVector p = pointer.getTransformedCenter();
     // object is the rotation center
     SimpleVector o = object.getTransformedCenter();
     // v is the vector from the object to the pointer
     SimpleVector v = p.calcSub(o);
     // this shows that v.length is not constant!
     System.out.println(p+" "+v.length());
     // make a copy of v
     SimpleVector w = new SimpleVector(v);
     // rotate the copy a little bit
     w.rotateY(dy);
     // set the pointer to the new position = move it the difference
     // between old and new position
     pointer.translate(v.calcSub(w));


I let this code run every time I move the mouse. The problem is that it is not stable - the pointer rotates around the object, but it is also moving away from it (length of v is increasing). If I comment the rotation line out, than it is stable (ok, it does nothing then). Can this be a number precision error? What would be the best way to do this task? Another question is how to set an object to a new Position. A camera has a position, but an object does not have a setTransformedCenter-Method or something like that, and that is the reason I came to this translation construct.

Thanks for your help for this bloody beginner

Sebastian

Hi,

a camera in 3d space can be defined by position, direction and up (the orientation). I found no way to access this up information in JPCT, and this is especially missing in the camera.lookAt(obj) method.

I need this for implementing a camera that can be rotated around a given object with the mouse. I wrote the following code for rotating around a object at the x axis:


     SimpleVector obj = object.getTransformedCenter();
     SimpleVector cam = camera.getPosition();
     SimpleVector v = cam.calcSub(obj);      
     Matrix m = new Matrix();
     m.rotateX(dx);
     v.matMul(m);
     v.add(obj);
     camera.setPosition(v);
     camera.lookAt(obj);


When I rotate around an object this way, the orientation flips around (upside-down) when I get close to a 180 degree rotation.

I think that this information is somehow stored in the camera.getBack() rotation matrix, but the math part of my has been shrunken since school  :oops:

By the way, did anyone use quaternions? I found some nice articles in the web about this, but I don't know how to integrate this with JPCT right know, I think there wait a lot of little traps like the column-or-row matrix question and such things when converting those examples from DirectX to the java JPCT world.

Thanks for any help

Sebastian[/code][/quote]

Is it possible to use any kind of isometric projection (or axonometric projection) in JPCT, that means a non perspective view of an object? I don't need a perfect isometric view but it should allmost look like it. I know that this could be done in reality by setting the camera position practical to infinity and use a very high zoom factor, but I don't see how to get this in JPCT.

Thanks for any help

Sebastian

Ok, I believe that would be possible. But if you could show by example the code of the M2 - Loader, it would be much easyer :-)

Hi,

first I must say "thank you" for this great library. We think about using it in a commercial system. Would it be possible to see the source? I think about writing a additional loader for other formats or for retrieving more information (like texture and animation) from the files.

Best Regards,

Sebastian