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[KyroMaster]

I work for an university project which is using java3d, and we'll like to switch to another engine because j3d sucks 
I'd like to use xith as I want to get into this engine for my own projects, too.
The problem is, we use a head tracker, and therefor we need to set an arbitrary frustrum ("view") matrix for the projection. Is this possible in xith? And if it is, will overlays still work correctly. In j3d, you have to go into a "compatibility mode" when setting a custom frustrum matrix, and then overlays stop to work.

[Marvin Fröhlich]

Are you really sure, you want to modify the projection matrix? I assume you actually want to modify the camera (view matrix). And this is perfectly possible in Xith3D and it won't affect overlays or the HUD in any way.

Marvin

[KyroMaster]

Are you really sure, you want to modify the projection matrix?

Yes, unfortunately 
We do augmented reality (aka "Heads-Up-Display") and we use a calibration algorithm which gives us the raw projection matrix. AFAIK in general 3D engines do this

glMatrixMode( GL_PROJECTION );
glFrustrum(left, right, bottom, top, near, far)

which calculated a standard perspective projection matrix and we'd need to use

glMatrixMode( GL_PROJECTION );
glLoadMatrixf( &customMatrix);

do you think this could work in xith? Does xith support orthogonal projection together with HUD, because if it does it should be no problem and I could just try to implement it 

Thanks for your help!

[Marvin Fröhlich]

Yes, unfortunately 
We do augmented reality (aka "Heads-Up-Display") and we use a calibration algorithm which gives us the raw projection matrix. AFAIK in general 3D engines do this

glMatrixMode( GL_PROJECTION );
glFrustrum(left, right, bottom, top, near, far)

which calculated a standard perspective projection matrix and we'd need to use

glMatrixMode( GL_PROJECTION );
glLoadMatrixf( &customMatrix);

do you think this could work in xith?

Well, I guess, you could simply use a little trick. Just compose the view matrix with the inverse of the projection matrix (from the left). This should neutralize the projection matrix and you could use your own custom projection matrix as the regular view matrix. I guess, this should work. But we could also provide the possibility to apply a custom projection matrix. But I would need to check, what would have to be done.

I guess, the simplest solution would be to setup the view and the canvas/viewport in a way, that the automatic internal calculation does exactly, what you need.

In any case, it is possible.

Does xith support orthogonal projection together with HUD, because if it does it should be no problem and I could just try to implement it 

Yes. Definitely. Xith supports orthogonal or perspective projection for each RenderPass separately. It also has a complete HUD implementation ready to be used out of the box. And it of can course be rendered on top of anything without being affected by it.

Marvin

['n ddrylliog]

I don't see the point of forcing users to circumvent high-level APIs with computing tricks in order to access low-level ones. What is simpler than allowing setting the raw matrix ?  Am I missing something here ?

[Marvin Fröhlich]

I don't see the point of forcing users to circumvent high-level APIs with computing tricks in order to access low-level ones. What is simpler than allowing setting the raw matrix ?  Am I missing something here ?

I said, that is is abolutely possible. I just wan't sure, if this really was, what he wanted. Allowing to set the raw matrix is simple and can be done.

Marvin

[KyroMaster]

If it would be possible and simple to implement, it would be very cool, for sure 

[Marvin Fröhlich]

Please update from SVN and use View.setProjection().

Enjoy.

Marvin