Better Model Projection

[Mercotui]

In the augmentation widget, currently the model projection matrix is defined as:

_mat_projection.ortho (-2.0f, +2.0f, -2.0f, +2.0f, 1.0f, 25.0f);

This should be changed to a more realistic perspective projection, maybe using camera data if available?

[Mercotui]

So as a general improvement, a guessed FOV can be used, for example as discussed here.

On android there are also APIs to query the camera calibration, but support may vary as discussed here.