Sorry, I didn't really mean it to be that sarcastic -- more educational with a humorous note. But I was a bit rushed, so I kind of skipped over the explanation part, and the humor, well, my humor is of a hit-or-miss variety...but usually I have the good sense to not apply it in online discussions like that.
You'll notice that Robert's code does exactly what I said -- an odd number of axis in the scaling are negative. Think about what that does -- it mirrors it across the plane formed by the other two axis. Any odd number of mirrorings will leave you with the handedness of the coordinate system flipped. This can be across ANY planes. But you can decompose any set of linear transformations to be a scaling times every everything else, so you can flip, then move that plane around, to achieve mirroring across any plane whatsoever. There's no other way to do it, this is the complete set. See, I really was giving you a complete solution -- in condensed form! Now, I was slightly careless in my description. If you scale any axis by zero, you reduce the number of dimensions by one. Do it once, and you have Flatland -- and you no longer have a concept of "handedness" at all. Do it twice, and you get a linear world. Not very interesting. Do it three times, and you've got a point -- but I can't see it! On Apr 29, 8:24 am, Juan Aranda-Alvarez <juan.arandaalva...@gmail.com> wrote: > Thanks, wow, it really was simple. Thanks for the sane answer. > > Juan > > > > > > On Wed, Apr 28, 2010 at 11:02 PM, Robert Green <rbgrn....@gmail.com> wrote: > > Juan, their sarcasm is well-founded. It's not only possible but > > trivial. > > > One easy way to change the coordinate system: > > > // start drawing > > gl.glMatrixMode(GL10.GL_MODELVIEW); > > gl.glLoadIdentity(); > > gl.glScalef (1, 1, -1); > > GLU.gluLookAt(gl, pos.x, pos.y, pos.z, lookAt.x, lookAt.y, lookAt.z, > > upVec.x, upVec.y, upVec.z); > > > Enjoy your new left-handed coordinate system. > > > On Apr 28, 7:39 pm, Bob Kerns <r...@acm.org> wrote: > > > You mean, other than any affine transform that decomposes to include > > > scaling of an odd number of axis by a negative value? Nope, other than > > > that infinite number of ways, nope, no way. > > > > On Apr 27, 7:13 pm, Juan Aranda-Alvarez <juan.arandaalva...@gmail.com> > > > wrote: > > > > > OpenGL works in 3D space, so if you would like another orientation you > > could > > > > rotate the scene moving the POV (camera) position. But there is no way > > to > > > > move from a right-hand coordinate system to a Left-side one. > > > > -- > > > You received this message because you are subscribed to the Google > > > Groups "Android Developers" group. > > > To post to this group, send email to android-developers@googlegroups.com > > > To unsubscribe from this group, send email to > > > android-developers+unsubscr...@googlegroups.com<android-developers%2Bunsubs > > > cr...@googlegroups.com> > > > For more options, visit this group athttp:// > > groups.google.com/group/android-developers?hl=en > > > -- > > You received this message because you are subscribed to the Google > > Groups "Android Developers" group. > > To post to this group, send email to android-developers@googlegroups.com > > To unsubscribe from this group, send email to > > android-developers+unsubscr...@googlegroups.com<android-developers%2Bunsubs > > cr...@googlegroups.com> > > For more options, visit this group at > >http://groups.google.com/group/android-developers?hl=en > > -- > You received this message because you are subscribed to the Google > Groups "Android Developers" group. > To post to this group, send email to android-developers@googlegroups.com > To unsubscribe from this group, send email to > android-developers+unsubscr...@googlegroups.com > For more options, visit this group > athttp://groups.google.com/group/android-developers?hl=en -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
