Class CurveUtility

A collection of methods for extracting information about BezierCurve types.

Inheritance
Object
CurveUtility
Inherited Members
Namespace: UnityEngine.Splines
Syntax
public static class CurveUtility

Methods

ApproximateLength(BezierCurve)

Calculate the approximate length of a BezierCurve. This is less accurate than CalculateLength(BezierCurve, Int32), but can be significantly faster. Use this when accuracy is not paramount and the curve control points are changing frequently.

Declaration
public static float ApproximateLength(BezierCurve curve)
Parameters
Type Name Description
BezierCurve curve

The BezierCurve to calculate length.
Returns
Type Description
Single

An estimate of the length of a curve.

CalculateCurveLengths(BezierCurve, DistanceToInterpolation[])

Populate a pre-allocated lookupTable array with distance to 't' values. The number of table entries is dependent on the size of the passed lookupTable.

Declaration
public static void CalculateCurveLengths(BezierCurve curve, DistanceToInterpolation[] lookupTable)
Parameters
Type Name Description
BezierCurve curve

The BezierCurve to create a distance to 't' lookup table for.
DistanceToInterpolation[] lookupTable

A pre-allocated array to populate with distance to interpolation ratio data.

CalculateLength(BezierCurve, Int32)

Calculate the length of a BezierCurve by unrolling the curve into linear segments and summing the lengths of the lines. This is equivalent to accessing GetCurveLength(Int32).

Declaration
public static float CalculateLength(BezierCurve curve, int resolution = 30)
Parameters
Type Name Description
BezierCurve curve

The BezierCurve to calculate length.
Int32 resolution

The number of linear segments used to calculate the curve length.
Returns
Type Description
Single

The sum length of a collection of linear segments fitting this curve.
See Also

EvaluateAcceleration(BezierCurve, Single)

Given a bezier curve, return an interpolated acceleration at ratio t.

Declaration
public static float3 EvaluateAcceleration(BezierCurve curve, float t)
Parameters
Type Name Description
BezierCurve curve

A cubic bezier curve.
Single t

A value between 0 and 1 representing the ratio along the curve.
Returns
Type Description
float3

An acceleration vector on the curve.

EvaluateCurvature(BezierCurve, Single)

Given a bezier curve, return an interpolated curvature at ratio t.

Declaration
public static float EvaluateCurvature(BezierCurve curve, float t)
Parameters
Type Name Description
BezierCurve curve

A cubic bezier curve.
Single t

A value between 0 and 1 representing the ratio along the curve.
Returns
Type Description
Single

A curvature value on the curve.

EvaluatePosition(BezierCurve, Single)

Given a bezier curve, return an interpolated position at ratio t.

Declaration
public static float3 EvaluatePosition(BezierCurve curve, float t)
Parameters
Type Name Description
BezierCurve curve

A cubic bezier curve.
Single t

A value between 0 and 1 representing the ratio along the curve.
Returns
Type Description
float3

A position on the curve.

EvaluateTangent(BezierCurve, Single)

Given a bezier curve, return an interpolated tangent at ratio t.

Declaration
public static float3 EvaluateTangent(BezierCurve curve, float t)
Parameters
Type Name Description
BezierCurve curve

A cubic bezier curve.
Single t

A value between 0 and 1 representing the ratio along the curve.
Returns
Type Description
float3

A tangent on the curve.

GetDistanceToInterpolation(BezierCurve, Single)

Gets the normalized interpolation, (t), that corresponds to a distance on a BezierCurve.

Declaration
public static float GetDistanceToInterpolation(BezierCurve curve, float distance)
Parameters
Type Name Description
BezierCurve curve

The BezierCurve to calculate the distance to interpolation ratio for.
Single distance

The curve-relative distance to convert to an interpolation ratio (also referred to as 't').
Returns
Type Description
Single

Returns the normalized interpolation ratio associated to distance on the designated curve.
Remarks

It is inefficient to call this method frequently. For better performance create a DistanceToInterpolation cache with CalculateCurveLengths(BezierCurve, DistanceToInterpolation[]) and use the overload of this method which accepts a lookup table.

GetDistanceToInterpolation<T>(T, Single)

Return the normalized interpolation (t) corresponding to a distance on a BezierCurve. This method accepts a look-up table (referred to in code with acronym "LUT") that may be constructed using CalculateCurveLengths(BezierCurve, DistanceToInterpolation[]). The built-in Spline class implementations (Spline and NativeSpline) cache these look-up tables internally.

Declaration
public static float GetDistanceToInterpolation<T>(T lut, float distance)
    where T : IReadOnlyList<DistanceToInterpolation>
Parameters
Type Name Description
T lut

A look-up table of distance to 't' values. See CalculateCurveLengths(BezierCurve, DistanceToInterpolation[]) for creating this collection.
Single distance

The curve-relative distance to convert to an interpolation ratio (also referred to as 't').
Returns
Type Description
Single

The normalized interpolation ratio associated to distance on the designated curve.
Type Parameters
Name Description
T

The collection type.

Split(BezierCurve, Single, out BezierCurve, out BezierCurve)

Decompose a curve into two smaller curves matching the source curve.

Declaration
public static void Split(BezierCurve curve, float t, out BezierCurve left, out BezierCurve right)
Parameters
Type Name Description
BezierCurve curve

The source curve.
Single t

A mid-point on the source curve defining where the two smaller curves control points meet.
BezierCurve left

A curve from the source curve first control point to the mid-point, matching the curvature of the source curve.
BezierCurve right

A curve from the mid-point to the source curve fourth control point, matching the curvature of the source curve.