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 Mouse to 3D space?  (Read 3300 times) 0 Members and 1 Guest are viewing this topic.
Varkas
 « Posted 2012-11-15 11:30:34 »

I'd assume that it should be possible to use the projection matrix "backwards", and calculate a line in 3D space from the 2D mouse coordinate on the screen. Intersecting this line with the objects it should be possible to find the object(s) which was pointed at.

Is this the way to do it? And if yes, how does one do the math? Matrix operations are nontrivial for me, so I will ned a bit of help with that. Thanks

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ra4king

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 « Reply #1 - Posted 2012-11-16 00:38:50 »

sproingie

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 « Reply #2 - Posted 2012-11-16 00:52:15 »

The term that you might find handy to google for is "ray picking".  A "simple" way to get that ray is with a couple calls to GLU.gluUnproject, using your near and far planes as Z values.  There's probably better ways to do it now though.
Agro
 « Reply #3 - Posted 2012-11-16 02:08:38 »

It is actually really easy. this function will return a vector in the direction you are pointing in, assuming you have a yaw and pitch value(you can't just get it from a single coordinate, you need some sense of direction too):

 1  2  3 `Vector3D getDirectionVector() {   return new Vector3D(-Math.cos(pitch * Math.PI / 180.0) * Math.sin(yaw * Math.PI / 180.0), Math.sin(pitch * Math.PI / 180.0), -Math.cos(pitch * Math.PI / 180.0) * Math.cos(yaw * Math.PI / 180.0));}`

Note: This is assuming yaw and pitch are in degrees.

Tell me if it didn't work, might've messed up something there.

Then after that, you can use ray tracing or some other good  method to find the object(s) you're pointing at.

ra4king

JGO Kernel

Medals: 508
Projects: 3
Exp: 5 years

I'm the King!

 « Reply #4 - Posted 2012-11-16 02:13:32 »

Try to keep pitch and yaw as radians to save performance.

/nitpicky

Agro
 « Reply #5 - Posted 2012-11-16 02:14:25 »

Oh yeah, always use radians. Degrees is just better for debugging/presentation honestly, but personally I like it better. >

Varkas
 « Reply #6 - Posted 2012-11-16 13:08:21 »