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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