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Action:
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Evaluates the straight line, which is tangent to a planar bs3curve, and passes it through the given point.
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Filename:
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kern/kern_scm/crv_scm.cxx
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Syntax:
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(curve:bs3-eval-tan-pt curve point guess-param)
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Arg Types:
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curve
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edge
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point
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position
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guess-param
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real
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Returns:
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position
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Description:
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Determines a position on a bs3_curve where a line from a given position is tangent to the curve. Uses a guess parameter value to aid the solution (especially where there are multiple solutions).
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curve is the input bs3curve whose tangent position has to be determined.
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point is the input position that lies on the required line.
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guess-param is the guess parameter value to aid the solution (especially where there are multiple solutions).
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Example:
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; curve:bs3-eval-tan-pt
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; Create a spline edge.
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(define spl (edge:spline (list
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(position 0 0 0) (position 5 5 0)
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(position 10 15 0) (position 15 20 0)
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(position 20 15 0) (position 25 5 0)
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(position 30 0 0))))
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;; spl
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; Determine the tangent point on the curve that
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; passes through the position (0 25 0).
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(curve:bs3-eval-tan-pt spl (position 0 25 0) 20)
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;; #[position 15.6785064292946 19.8870807275491 0]
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