findSpan function

dynamic findSpan(dynamic p, dynamic u, dynamic U)

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• NURBS Utils

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Implementation

/*
Finds knot vector span.

p : degree
u : parametric value
U : knot vector

returns the span
*/
findSpan( p, u, U ) {

	var n = U.length - p - 1;

	if ( u >= U[ n ] ) {

		return n - 1;

	}

	if ( u <= U[ p ] ) {

		return p;

	}

	var low = p;
	var high = n;
	var mid = Math.floor( ( low + high ) / 2 );

	while ( u < U[ mid ] || u >= U[ mid + 1 ] ) {

		if ( u < U[ mid ] ) {

			high = mid;

		} else {

			low = mid;

		}

		mid = Math.floor( ( low + high ) / 2 );

	}

	return mid;

}