Compute the extents of the coordinate system before this {@link #isAffine() affine} transformation was applied
and store the resulting corner coordinates in <code>corner</code> and the span vectors in
<code>xDir</code>, <code>yDir</code> and <code>zDir</code>.
<p>
That means, given the maximum extents of the coordinate system between <code>[-1..+1]</code> in all dimensions,
this method returns one corner and the length and direction of the three base axis vectors in the coordinate
system before this transformation is applied, which transforms into the corner coordinates <code>[-1, +1]</code>.
<p>
This method is equivalent to computing at least three adjacent corners using {@link #frustumCorner(int, Vector3d)}
and subtracting them to obtain the length and direction of the span vectors.
@param corner
will hold one corner of the span (usually the corner {@link Matrix4d#CORNER_NXNYNZ})
@param xDir
will hold the direction and length of the span along the positive X axis
@param yDir
will hold the direction and length of the span along the positive Y axis
@param zDir
will hold the direction and length of the span along the positive z axis
@return this
Compute the extents of the coordinate system before this {@link #isAffine() affine} transformation was applied and store the resulting corner coordinates in <code>corner</code> and the span vectors in <code>xDir</code>, <code>yDir</code> and <code>zDir</code>. <p> That means, given the maximum extents of the coordinate system between <code>[-1..+1]</code> in all dimensions, this method returns one corner and the length and direction of the three base axis vectors in the coordinate system before this transformation is applied, which transforms into the corner coordinates <code>[-1, +1]</code>. <p> This method is equivalent to computing at least three adjacent corners using {@link #frustumCorner(int, Vector3d)} and subtracting them to obtain the length and direction of the span vectors.
@param corner will hold one corner of the span (usually the corner {@link Matrix4d#CORNER_NXNYNZ}) @param xDir will hold the direction and length of the span along the positive X axis @param yDir will hold the direction and length of the span along the positive Y axis @param zDir will hold the direction and length of the span along the positive z axis @return this