forward

Gets the basis vector representing the Z-axis of the coordinate system after this matrix's transformation. This is commonly referred to as the "forward" vector.

For a row-major matrix, this vector is extracted directly from the first three elements of the third row: (m20, m21, m22).

If the matrix includes scaling, this vector's length will reflect that scaling, and it is not guaranteed to be a unit vector. To get a pure direction, normalize this vector.

The interpretation of this vector as "forward" (e.g., pointing into the screen) depends on the coordinate system's handedness (right-handed vs. left-handed).