Multiple Patch Surface (SM)

##
Multiple Patch Surface(SM)

    Purpose:  To cover a rectangular region with surface patches.

    Card:

            SM  I1  I2   F1    F2    F3    F4    F5    F6    blank

                NX  NY   X1    Y1    Z1    X2    Y2    Z2

            A second card with the following format must immediately follow
            a SM card:

            SC           F1    F2    F3    F4    F5    F6    blank

                         X3    Y3    Z3

    Parameters:

            Integers:
                NX    (I1)  \ The rectangular surface is divided into NX patches
                            | from corner 1 to corner 2 and NY patches from
                NY    (I2)  / corner 2 to corner 3.

    	Decimal Numbers:
    	    X1    (F1) \
    	    Y1    (F2) | X, Y, Z coordinates of corner 1
    	    Z1    (F3) /

    	    X2    (F4) \
    	    Y2    (F5) | X, Y, Z coordinates of corner 2
    	    Z2    (F6) /

    	    X3    (F7) \
    	    Y3    (F8) | X, Y, Z coordinates of corner 3
    	    Z3    (F9) /

    Notes:

          o  The division of the rectangle into patches is as illustrated in
    	 figure 6 "Rectangular Surface Covered by Multiple Patches".

          o  The direction of the outward normals ^n of the patches is determined
    	 by the ordering of corners 1, 2, and 3 and the right-hand rule.  The
    	 vectors ^t1 are parallel to the side from corner 1 to corner 2 and
    	 ^t2 = ^n x ^t1.  The patch may have arbitrary orientation.

          o  If the sides between corners 1 and 2 and between corners 2 and 3 are
    	 not perpendicular, the complete surface and the individual patches
    	 will be parallelograms.

          o  Multiple SC cards are not allowed with SM.

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