* move the focus distance from DofOptions to Camera
The DofOption parameter is now deprecated, but will still work if the
focus distance is not set on Camera.
* A few new helper APIs on Camera
- getFocalLength() which returns the focal length used internally for
DoF computations.
- computeEffectiveFov() and computeEffectiveFocalLength() which can be
used to better simulate a real camera's FOV changes with the
focus distance.
Modified gltf_viewer so it uses the effective fov/focallendth when
DoF is active.
* simplify setLensProjection
We can call setProjection directly instead of converting to a fov
first, which ends up performing atan(tan(x)).
Also improve parameters names.
- Add a "shift" parameter to Camera. This has the effect of translating
the viewport, without changing its size.
This is an effect similar to using a shift lens.
- Camera::setScaling() now takes a double2 instead of double4, this is
because scaling the result of the projection in the Z direction
can lead to very confusing problems -- it will essentially move the
near/far planes, and we don't want to expose that as a public API.
- setCustomProjection() now allows to set a different projection for
rendering and culling (useful for e.g. for using an infinite far
rendering projection matrix).
math/mathwfd.h forward declares all {mat|vec}{2|3|4}<> classes,
which allows us to remove their respective #include in a lot of
our public headers.
Our math headers are full of templates, so this should help build times
a bit.
Also we want to keep the public headers as minimalist as possible.
