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Action:
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Creates visible vector field lines along an edge or wire.
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Filename:
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kern/kern_scm/law_scm.cxx
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APIs:
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api_hedgehog
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Syntax:
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(law:hedgehog
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{path vector-list [number-hair [size]]} |
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{hair-law base-law start-x end-x
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{[number-hair] | [start-y end-y [number-hair]] |
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[start-y end-y start-z end-z [number-hair]]}})
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Arg Types:
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path
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entity
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vector-list
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law | (law ...)
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number-hair
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integer
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size
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real
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hair-law
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law | string | gvector
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base-law
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law | string | position
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start-x
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real
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end-x
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real
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start-y
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real
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end-y
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real
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start-z
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real
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end-z
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real
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Returns:
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boolean
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Description:
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The
law:hedgehog extension defines vector fields that are attached to a curve. They are useful for defining orientation when sweeping along a non-planar path. There are two major ways to use this command. The determination as to which method is used is based on the first argument type.
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If the first argument is an
entity, as would be the case for a wire body or edge, then that argument is assumed to be thepath and should be followed by a Scheme list of laws,
vector-list Optionally, the number of hairs on the hedgehog and its size can be specified.
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If the first argument is not an
entity, then it is assumed to be a
hair-law, which can be a
law,
string, or
gvector.
hair-law specifies the direction for the hair vectors. This is followed by
base-law., which specifies what is to receive the vector field. Thereafter, this can be followed by 0 or up to 5 arguments.
number-hair specifies the number of vectors to use. The
start and
end parameters limit the range for displaying the vector field.
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Example:
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; law:hedgehog
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; The edge is not required, but is useful
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; for visualization purposes. It is defined
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; the same as base-law.
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(define edge1
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(edge:law "vec(cos(x),sin(x),x/10)" 0 50))
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;; edge1
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(define base-law
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(law "vec(cos(x),sin(x),x/10)"))
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;; base-law
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(define vector-law (law "vec(cos(x),sin(x),0)"))
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;; vector-law
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(define hedgehog1 (law:hedgehog vector-law
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base-law 0 50 200 ))
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;; hedgehog1
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; Another example.
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; Clear out the result of the previous example
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(part:clear)
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;; #t
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; The face is not required, but is useful
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; for visualization purposes. It is defined
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; the same as base-law.
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(define face1
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(face:law "vec(x,y,cos(x)*sin(y))" -5 5 -5 5))
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;; face1
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(define base-law1(law "vec(x,y,cos(x)*sin(y))"))
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;; base-law1
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(define dx (law:derivative base-law))
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;; dx
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(define dy(law:derivative base-law1 "y"))
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;; dy
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(define norm (law "cross(law1,law2)" dx dy))
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;; norm
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(define hedgehog2 (law:hedgehog norm
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base-law -5 5 -5 5 20 ))
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;; hedgehog2
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; Another example.
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; Clear out the previous example
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(part:clear)
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;; #t
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(dl-item:erase hedgehog2)
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;; ()
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(define base-law2 (law "vec(x,y,z)"))
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;; base-law2
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(define hair-law (law "norm(vec(x,y,z))"))
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;; hair-law
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(define hedgehog3 (law:hedgehog hair-law
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base-law -10 10 -10 10 -10 10))
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;; hedgehog3
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; Clean up the DL items.
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;(dl-item:erase hedgehog3)
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; ()
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