toVector4
Converts this 3D vector into a 4D vector, treating it as a point in homogeneous coordinates.
The w-component of the resulting Vector4 is set to 1.0f. This is the standard representation for a point in 3D space when using 4x4 matrices for affine transformations (like translation, rotation, and scale). A w-component of 1.0f ensures that translations are correctly applied.
Return
A Vector4 with the same x, y, z components as this vector and a w-component of 1.0f.