Originally it was for more convenient usage of homogeneous coordinates
in shaders themselves, but it is actually not needed:
* When passing three-component vector (3D position) to `vec4`, the last
coordinate is implicitly set to `1`, thus there is no need to pass it
explicitly in each attribute.
* On the other hand, when passing three-component vector (2D position
in homogeneous coordinates) to `vec3` with Z explicitly set to `1`,
it still needs some swizzle magic to extend it to `vec4` gl_Position.
Passing it as two-component vector results in nearly the same magic
while saving precious memory.
Positions were originally done using Point2D/3D to simplify their
transformation using matrices and to some extent simplify their usage in
shaders. But now the disadvantages exceeded the advantages:
* They take 50% more for 2D positions and 33% more for 3D positions, as
last coordinate is always equal to 1, on the other hand when last
coordinate is errorneously not equal to 1 they have crazy behavior.
* Normalizing them or transforming them with anything else than with
matrices is PITA, as we need to strip the last component, do the
transformation, and then add the component back.
* All transformation handling classes (Complex, DualComplex,
Quaternion, DualQuaternion, Matrix3, Matrix4) now have convenience
functions for transforming points specified directly as
Vector2/Vector3 (and also for transforming vectors).
* When someone wants to use homogeneous coordinates with crazy last
component values, they can do so with plain Vector3 for 2D and
Vector4 for 3D and it will be less confusing than using Point2D/3D
which no important detail hidden.
Remaining unspecified components are set to 0, 0, 1, according to spec.
Also cleaned up and simplified the internals, added debug output
operators for attribute component count and types and tested the whole
thing.
The text will be rendered without all the nifty features like kerning
and it will most probably fail on everything non-latin, but HarfBuzz is
currently PITA on some systems.
HarfBuzz usage can be configured using USE_HARFBUZZ CMake option.
Next few commits will add requirement for "strongly typed" angles in all
function parameters, e.g.:
Matrix3::rotation(24.0_degf);
Math::sin(1.047_radf);
The purpose is to make angle entering less error-prone, e.g. not passing
degrees when radians should be etc.