-----Original Message----- From: Derek Augustus Ruths <[EMAIL PROTECTED]> To: Syrus Mesdaghi <[EMAIL PROTECTED]> Cc: [EMAIL PROTECTED] <[EMAIL PROTECTED]> Date: Thursday, June 01, 2000 8:56 AM Subject: Re: [JAVA3D] BUG!?: non-congruent transform above ViewPlatfor whena VALID matrix is applied ... > I recently dealt with a similar problem. I found that I received >non-congruent transform exceptions when I set the transform3D to a >rotation of zero about any axis. In code, this would look like: > > Transform3D t=new Transform3D(); > > t.rotX(0); > or > t.rotY(0); > or > t.rotZ(0); > > Any one of these seems to produce 'bad' results. I can't >charaterize the problem better because I don't really understand >it. However, you might check your code and check any cases where you >might rotate by zero. Once I ensured I wasn't rotating by zero, the >problem vanished. Hope this helps. > > DereK > >On Thu, 1 Jun 2000, Syrus Mesdaghi wrote: > >> Hello everyone, >> >> I've been having difficulty writing Behaviors that Manipulate the View's Transform. I use such behaviors extensively in order to manage the camera's movement in our games that are written for one of our Java3D based Engines. The problem is that if I run some of my demos for a little while, eventually the engine crashes and I get the following error: >> >> Exception occurred during Behavior execution: >> javax.media.j3d.BadTransformException: non-congruent transform above ViewPlatform >> at javax.media.j3d.TransformGroupRetained.setTransform(TransformGroupRetained.j ava:118) >> at javax.media.j3d.TransformGroup.setTransform(TransformGroup.java:111) >> >> As I mentioned can happen at any point. As a matter of fact, some of my demos can run perfectly without any problem. I have noticed that this occurs when the camera transform is rotating. For this matter, I left a small chance that the difficulty is related to floating point miscalculations. I finally got the chance to try to troubleshoot this problem and after testing many different cases, I realize that in some cases, there can be a Matrix4f that can be applied to an object without any difficulty, but when the very same Matrix (4f) is applied to the View Platform, the exception is thrown. In order to illustrate this scenario, I have implemented a sample app named TestUniverse that can apply a matrix to an Object's transform, or the ViewPlatform's transform. Pressing the key "S" cause the app to set the object's transform, and "C" cause the app to the ViewPlatform's transform. As you will be able to see, only the second scenario causes an exception to be thrown. >> >> In order to get a Matrix with these special values, I ran one of my demos for about 5 min and recorded the transform's data that cause the Engine to crash. Here is the transform: >> >> >> >> 1.0, 0.0, 0.0, 0 >> 0.0, 0.20792245864868164, 0.9781964421272278, 0 >> 0.0, -0.9781964421272278, 0.20792245864868164, 0 >> 0.0, 0.0, 0.0, 1.0 >> >> If the above data reveal an obvious problem, please let me know what is going on. If the problem is not too obvious, you should run the attached app. >> >> Please let me know if this is a BUG (or maybe floating point miscalculation, or ....). We are intending to show some of our student's projects at E3, so this problem has the highest priority on my list. >> >> I thank you in advanced, Take Care, >> >> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - >> Syrus Mesdaghi Full Sail Real World Education >> 3D Gaming Instructor 3300 University BLVD >> [EMAIL PROTECTED] Winter Park FL 32792 >> http://www.fullsail.com >> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - >> >> >> >> > thank you for the info, that is a good thing to know. Yet, the strange thing is that the values above are caused by using Vecmath calls and it has some rotation other than zero. if you run the TestUniverse.java and press "O" you will see the object rotate but the same matrix causes problem when applied to ViewPlatform's transform. Take Care, - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Syrus Mesdaghi Full Sail Real World Education 3D Gaming Instructor 3300 University BLVD [EMAIL PROTECTED] Winter Park FL 32792 http://www.fullsail.com - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - =========================================================================== To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff JAVA3D-INTEREST". For general help, send email to [EMAIL PROTECTED] and include in the body of the message "help".
