Nope.... this isn't what I've said. I have as a starting point, a pair of points in space that define the orientation of an object. Think of them as the endpoints of a cylinder. The goal is to rotate that cylinder so that the ends of the cylinder are at the pair of points.
Notice that we do NOT have any rotational angles to work with. Only a pair of points in 3space. Obviously what I'm describing is to transform a pair of points in 3space to a set of rotational angles. Now, if you're thinking "just read the angles off of the cylinder's transform", remember that the cylinder has not been rotated yet. I don't have those rotations. I have a pair of endpoints. This problem could like be solved with my own custom code, but I wonder if Java3d has any implicit tools (Matrix, Vector) which can facilitate this conversion from points in 3space to the transform. -- John On Sun, 30 Sep 2001, Eric Reiss wrote: > Date: Sun, 30 Sep 2001 22:30:28 -0400 > From: Eric Reiss <[EMAIL PROTECTED]> > Reply-To: Discussion list for Java 3D API <[EMAIL PROTECTED]> > To: [EMAIL PROTECTED] > Subject: Re: [JAVA3D] How to rotate objects? > > I think we still need to clear some things up here. First you said you > wanted to rotate an object to a known rotation value, so I showed you how > to use the setRotation method to set the object to an exact orientation > about the XYZ axises. In this case, we just did a SET, we didn't care how > the object was originally orientated (rotation wise). > > If you want to rotate an object by an additional amount then all you have > to do is to do a GET on the rotation and put that into a Matrix3d instead > of creating a Matrix3d and setting it to the identity matrix, you set it to > the existing rotation matrix of the object. Next you create a new rotation > matrix3d and do the rotX, rotY and rotZ with the angles on this > matrix. Finally you multiple the two matrices together and then to the > setRotation method with this resulting matrix. > > This is how you would add a rotation to an object's current rotation. > > > > > > At 09:41 PM 09/30/2001 -0400, you wrote: > >Well, the rotations that we had discussed before assume that you know the > >component angles for each coordinate. In some cases, I know the endpoints > >of a cylinder. Don't know the angle that this cylinder makes with any > >particular axis. Just know the endpoints. So how would I transform a > >pair of endpoints into angles that allow me to rotate that cylinder? > > > >-- John > > > >On Sun, 30 Sep 2001, Eric Reiss wrote: > > > > > Date: Sun, 30 Sep 2001 20:42:22 -0400 > > > From: Eric Reiss <[EMAIL PROTECTED]> > > > Reply-To: Discussion list for Java 3D API <[EMAIL PROTECTED]> > > > To: [EMAIL PROTECTED] > > > Subject: Re: [JAVA3D] How to rotate objects? > > > > > > I think you need to explain this a little more. Getting a rotation from > > > points would require a little more explanation. > > > > > > At 08:37 PM 09/30/2001 -0400, you wrote: > > > >Thanks... > > > > > > > >I tried something similar to this but I instantiated the Transform3d with > > > >the rotation matrix as one of the constructor's parameters. The API > > > >reference says you can do this but it didn't work. I'll try your > > > >suggestion (using setRotation) and see if that does the trick. > > > > > > > >Oh, one more question... is there an easy way to create a rotation matrix > > > >based on a pair of Points or Vectors describing two endpoints? I don't > > > >necessarily know the angle for rotations. Sometimes I start with the > > > >endpoints. > > > > > > > >-- John > > > >-- > >_____________________________________________________ > > > >John T. Nelson > >President | Computation.com Inc > >mail: | [EMAIL PROTECTED] > >company: | http://www.computation.com/ > >journal of computation: | http://www.computation.org/ > >_____________________________________________________ > >"Providing quality IT consulting services since 1992" > > > >=========================================================================== > >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". > > *********************************************************************** > Eric N. Reiss > MEMS Manager > Swanson Center for Product Innovation > Department of Mechanical Engineering > School of Engineering - University of Pittsburgh > > 3700 O'Hara Street > 647 Benedum Hall > Pittsburgh, Pennsylvania 15261 > Phone: 412-624-9696 > FAX: 412-624-7701 > Email: [EMAIL PROTECTED] > http://www.sigda.org/Eric/ > *********************************************************************** > > =========================================================================== > 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". > -- _____________________________________________________ John T. Nelson President | Computation.com Inc mail: | [EMAIL PROTECTED] company: | http://www.computation.com/ journal of computation: | http://www.computation.org/ _____________________________________________________ "Providing quality IT consulting services since 1992" =========================================================================== 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".
