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Action:
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Creates a law that returns the positions of the defining surface.
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Derivation:
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surface_law_data : base_surface_law_data : law_data : ACIS_OBJECT : -
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Syntax:
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SURF
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Description:
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surf returns the positions of the defining surface at the parameter value. This law symbol is a way to pass a surface into a law for other purposes, such as evaluation. The dimension of the input,
my_surface_law_data, is two, but when
surf is evaluated, it returns an item in three dimensions.
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ACIS defines its own parameter range for a surface which is used by this law.
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Example:
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; law "SURF"
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; Create a surface to evaluate. (define my_sphere (solid:sphere (position 0 0 0) 10))
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;; my_sphere
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; => #[entity 2 1]
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(define my_surflaw (law "surf(surf1)"
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(car (entity:faces my_sphere))))
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;; my_surflaw
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; => #[law "SURF(SURF1)"]
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(define my_sveclaw (law "surfvec(law1,
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vec(x,y,z), vec(a4, a5))" my_surflaw))
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;; my_sveclaw
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; my_sveclaw =>
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; [SURFVEC(SURF(SURF1),VEC(X,Y,Z), VEC(A4,A5))" ]
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(law:eval my_sveclaw (list 0 0 1 0 0))
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;; (1 0 0 0)
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; The law created takes an xyz vector and a uv
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; position on the surface. It returns a uv vector
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; in the direction of the given xyz vector at the
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; given uv position on the surface. It also returns
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; as the last two arguments the uv positions. The uv
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; position is echoed.
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; Here is an example at the pole.
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(law:eval my_sveclaw
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(list 1 1 0 (law:eval "pi/2") 0))
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;; (-1 0 1.5707963267949 0.785398163401155)
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; At the pole, this response means that you have to
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; turn v by pi/4 to get the correct vector.
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