toMatrix

Converts this quaternion into an equivalent 4x4 rotation matrix.

The quaternion is first normalized internally to ensure that the resulting matrix represents a pure rotation (without any scaling). If this quaternion has a near-zero length, it cannot represent a valid rotation, and an identity matrix is returned as a safe fallback.

The conversion uses the standard mathematical formula to create a 3x3 rotation matrix from the components of the unit quaternion (x, y, z, w). This 3x3 matrix is then embedded in the top-left of the final 4x4 matrix.

The resulting matrix is suitable for post-multiplying column vectors (e.g., TransformedPoint = RotationMatrix * OriginalPoint).