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J3D: How to get VW coordinates from mouse?

 
Kevin Jaffe
Greenhorn
Posts: 15
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hi!
how do i map a mouse motion to the virtual coordinate space?
i have tried to use getPixelLocationInImagePlate, but i get
the results that seem wrong to me, although this may be
because i am confused about things such as "image plate",
"center eye", "screen"...
i set the ViewPlatform transform to:
1.0, 0.0, 0.0, 0.0
0.0, 1.0, 0.0, 0.0
0.0, 0.0, 1.0, 1.0
0.0, 0.0, 0.0, 1.0
(i.e. put the image plate at z=1.0), and I make a Box with dimensions (0.1, 0.1, 2.0). my understanding was that this
would put the corners of the box that are at z=1.0 right at
the image plate, and therefore that if i clicked at, say, the upper righthand corner with the mouse and converted to virtual world coordinates, i should recover (using getPixelLocationInImagePlate and getImagePlateToVworld) i would recover (0.5, 0.5, 1.), but i don't. i get
(0.5546875, 0.5234375, -1.4142135623730954)
the z-coordinate is not a worry (getPixelLocationInImagePlate always returns a z-coordinate of 0. for some reason). but i can't figure out why the x and y coordinates are not both much closer to 0.5.
strangely, the transform returned by getImagePlateToVworld() is
27.68208661417323, 0.0, 0.0, -6.4140625
0.0, 27.68208661417323, 0.0, -5.210937500000001
0.0, 0.0, 27.68208661417323, -1.4142135623730954
0.0, 0.0, 0.0, 1.0
which makes no sense to me; i expected the m23
component to be 0.0 instead of -1.414... besides
there is no reason for this factor of sqrt(2) to
crop up, since i set the image plate to z=1.0, not
to the "nominal" z of 1+sqrt(2).
the only think that is clear is that i am thoroughly
confused!
any help would be greatly appreciated!
thanks!
kj
 
John M. Gabriele
Ranch Hand
Posts: 232
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you might try this question at http://www.javagaming.org
good luck.
 
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