transform method
Transforms this vector by matrix o.
Applies the 2D affine transformation encoded in the top-left 2x2 portion
of o plus the translation column (m12, m13). The Z component is
treated as 0.
Implementation
Vector2 transform(Matrix o) => .vec2(
o.m0*x + o.m4*y + o.m8*0 + o.m12,
o.m1*x + o.m5*y + o.m9*0 + o.m13
);