how to get the projection of a point on a plane?

[AndyLau]

I  have a point on a plane and want to get its projection on the other. How can I?
Thanks!

[Guoshima]

don't really know what you mean .. the projection of a point on a place to what .. and why do you need it ?

[zingbat]

There is some math to do that but i dont know any way to do it directly in java3d. You need to use the vecmath libs and do the calcs yourself.

I supose you want to find the vector from the view to the point and then use that vector to project the point into any surface that gets on the way. You could use parallel projection or perpective but you probably need to do the calculations point by point if you want to project an entire shape of points. For that you need to read the about picking in the tutorial and in the specification.

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[Guoshima]

euh .. from your explenation I would think that this is defently a parallel projection and there are some quick ways to do this. I think there are some trick to this in the OpenGL Red Book 'cause OpenGL uses this to project the scene to the screen. Or just search the net for Parallel Projection and you'll find something ..

[AndyLau]

Thanks you all!