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Action:
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Evaluates an edge or a curve at the specified parameter and number of derivatives.
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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:eval edge-or-curve parameter [integer-type])
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Arg Types:
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edge-or-curve
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curve | edge
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parameter
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real
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integer-type
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integer
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Returns:
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(position) | (position gvector) | (position gvector gvector)
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Errors:
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EDGE with no
CURVE
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Description:
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The parameterization of all curves is normalized to lie in the interval 0 to 1; therefore, evaluating at
parameter=0 indicates the start point of the curve.
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edge-or-curve specifies an edge or a curve.
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parameter specifies the length of the curve to evaluate. If the specified parameter lies outside the range 0 to 1, this extension returns an implicit position. A spline can only reliably be evaluated for parametric values from 0 to 1; if
parameter is outside of this range for a spline edge, the returned value is meaningless.
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integer-type is 0, 1, or 2 and specifies how many derivatives to compute. 0 evaluates only the position on the curve; 1 evaluates the position and first derivative [tangent]; or 2 evaluates the position and the first and second derivatives.
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Example:
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; curve:eval
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; Create a circular edge.
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(define edge1
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(edge:circular
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(position 0 0 0) 25 0 185))
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;; edge1
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; Evaluate the edge at various
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; parameters and derivatives.
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(curve:eval edge1 0.45 0)
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;; (#[position 2.93843493644595 24.8267114238732 0])
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(curve:eval edge1 0.45 1)
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;; (#[position 2.93843493644595 24.8267114238732 0]
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;; #[gvector -80.1619535059791 9.48779243187324 0])
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(curve:eval edge1 0.45 2)
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;; (#[position 2.93843493644595 24.8267114238732 0]
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;; #[gvector -80.1619535059791 9.48779243187324 0]
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;; #[gvector -30.6347450861677 -258.83165434934 0])
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