>>434
OpenGL, the most popular graphics library in the world, requires that z value in
homogeneous clipping space be within the range between -w and w, as is the case
with your platform. Historically, I believe, this type of projection matrices
rather than DirectX-style projection matrices (0 < z < w) has been widly used.

>>437
You can use the upper-left 3x3 matrix of your transform matrix (from world space
to object space) to transform a direction vector into object space if and only if
the 3x3 matrix is orthonormal, which means the 3x3 matrix represents pure rotation
without any scaling or shearing. Otherwise (if the 3x3 matrix is not orthonormal),
you need to use the inverse transpose of the upper-left 3x3 matrix instead.

>>438
I agree. No Japanese translation is needed for us.
327, we hope you meet our request. Thanks in advance.