opensolid/geometry/2.1.0

NOTE: this package is not compatible with Elm 0.19.1

OpenSolid.QuadraticSpline3d

QuadraticSpline3d

A QuadraticSpline3d is a quadratic Bézier curve in 3D defined by three control points. This module contains functionality for

  • Evaluating points and derivatives along a spline
  • Scaling, rotating, translating or mirroring a spline
  • Converting a spline between local and global coordinates in different reference frames
type alias QuadraticSpline3d =
QuadraticSpline3d

Constructors

fromControlPoints : ( Point3d, Point3d, Point3d ) -> QuadraticSpline3d

Construct a spline from its three control points:

exampleSpline =
    QuadraticSpline3d.fromControlPoints
        ( Point3d.fromCoordinates ( 1, 1, 1 )
        , Point3d.fromCoordinates ( 3, 2, 1 )
        , Point3d.fromCoordinates ( 3, 3, 3 )
        )
on : SketchPlane3d -> QuadraticSpline2d -> QuadraticSpline3d

Construct a 3D spline lying on a sketch plane by providing a 2D spline specified in XY coordinates within the sketch plane.

QuadraticSpline3d.on SketchPlane3d.xz <|
    QuadraticSpline2d.fromControlPoints
        ( Point2d.fromCoordinates ( 1, 1 )
        , Point2d.fromCoordinates ( 3, 4 )
        , Point2d.fromCoordinates ( 5, 1 )
        )
--> QuadraticSpline3d.fromControlPoints
-->     ( Point3d.fromCoordinates ( 1, 0, 1 )
-->     , Point3d.fromCoordinates ( 3, 0, 4 )
-->     , Point3d.fromCoordinates ( 5, 0, 1 )
-->     )

Properties

controlPoints : QuadraticSpline3d -> ( Point3d, Point3d, Point3d )

Get the control points of a spline as a tuple.

( p1, p2, p3 ) =
    QuadraticSpline3d.controlPoints exampleSpline




--> p1 = Point3d.fromCoordinates ( 1, 1, 1 )
--> p2 = Point3d.fromCoordinates ( 3, 2, 1 )
--> p3 = Point3d.fromCoordinates ( 3, 3, 3 )
startPoint : QuadraticSpline3d -> Point3d

Get the start point of a spline. This is equal to the spline's first control point.

QuadraticSpline3d.startPoint exampleSpline
--> Point3d.fromCoordinates ( 1, 1, 1 )
endPoint : QuadraticSpline3d -> Point3d

Get the end point of a spline. This is equal to the spline's last control point.

QuadraticSpline3d.endPoint exampleSpline
--> Point3d.fromCoordinates ( 3, 3, 3 )
startDerivative : QuadraticSpline3d -> Vector3d

Get the start derivative of a spline. This is equal to twice the vector from the spline's first control point to its second.

QuadraticSpline3d.startDerivative exampleSpline
--> Vector3d.fromComponents ( 4, 2, 0 )
endDerivative : QuadraticSpline3d -> Vector3d

Get the end derivative of a spline. This is equal to twice the vector from the spline's second control point to its third.

QuadraticSpline3d.endDerivative exampleSpline
--> Vector3d.fromComponents ( 0, 2, 4 )

Evaluation

pointOn : QuadraticSpline3d -> Float -> Point3d

Get a point along a spline, based on a parameter that ranges from 0 to 1. A parameter value of 0 corresponds to the start point of the spline and a value of 1 corresponds to the end point.

QuadraticSpline3d.pointOn exampleSpline 0
--> Point3d.fromCoordinates ( 1, 1, 1 )


QuadraticSpline3d.pointOn exampleSpline 0.5
--> Point3d.fromCoordinates ( 2.5, 2, 1.5 )


QuadraticSpline3d.pointOn exampleSpline 1
--> Point3d.fromCoordinates ( 3, 3, 3 )
derivative : QuadraticSpline3d -> Float -> Vector3d

Get the deriative value at a point along a spline, based on a parameter that ranges from 0 to 1. A parameter value of 0 corresponds to the start derivative of the spline and a value of 1 corresponds to the end derivative.

QuadraticSpline3d.derivative exampleSpline 0
--> Vector3d.fromComponents ( 4, 2, 0 )


QuadraticSpline3d.derivative exampleSpline 0.5
--> Vector3d.fromComponents ( 2, 2, 2 )


QuadraticSpline3d.derivative exampleSpline 1
--> Vector3d.fromComponents ( 0, 2, 4 )

Note that the derivative interpolates linearly from end to end.

evaluate : QuadraticSpline3d -> Float -> ( Point3d, Vector3d )

Evaluate a spline at a given parameter value, returning the point on the spline at that parameter value and the derivative with respect to that parameter value;

QuadraticSpline3d.evaluate spline t

is equivalent to

( QuadraticSpline3d.pointOn spline t
, QuadraticSpline3d.derivative spline t
)

but is more efficient.

Transformations

reverse : QuadraticSpline3d -> QuadraticSpline3d

Reverse a spline so that the start point becomes the end point, and vice versa.

QuadraticSpline3d.reverse exampleSpline
--> QuadraticSpline3d.fromControlPoints
-->     ( Point3d.fromCoordinates ( 3, 3, 3 )
-->     , Point3d.fromCoordinates ( 3, 2, 1 )
-->     , Point3d.fromCoordinates ( 1, 1, 1 )
-->     )
scaleAbout : Point3d -> Float -> QuadraticSpline3d -> QuadraticSpline3d

Scale a spline about the given center point by the given scale.

exampleSpline
    |> QuadraticSpline3d.scaleAbout Point3d.origin 2
--> QuadraticSpline3d.fromControlPoints
-->     ( Point3d.fromCoordinates ( 2, 2, 2 )
-->     , Point3d.fromCoordinates ( 6, 4, 2 )
-->     , Point3d.fromCoordinates ( 6, 6, 6 )
-->     )
rotateAround : Axis3d -> Float -> QuadraticSpline3d -> QuadraticSpline3d

Rotate a spline counterclockwise around a given axis by a given angle (in radians).

exampleSpline
    |> QuadraticSpline3d.rotateAround Axis3d.z
        (degrees 90)
--> QuadraticSpline3d.fromControlPoints
-->     ( Point3d.fromCoordinates ( -1, 1, 1 )
-->     , Point3d.fromCoordinates ( -2, 3, 1 )
-->     , Point3d.fromCoordinates ( -3, 3, 3 )
-->     )
translateBy : Vector3d -> QuadraticSpline3d -> QuadraticSpline3d

Translate a spline by a given displacement.

displacement =
    Vector3d.fromComponents ( 2, 3, 1 )


exampleSpline
    |> QuadraticSpline3d.translateBy displacement
--> QuadraticSpline3d.fromControlPoints
-->     ( Point3d.fromCoordinates ( 3, 4, 2 )
-->     , Point3d.fromCoordinates ( 5, 5, 2 )
-->     , Point3d.fromCoordinates ( 5, 6, 4 )
-->     )
mirrorAcross : Plane3d -> QuadraticSpline3d -> QuadraticSpline3d

Mirror a spline across a plane.

QuadraticSpline3d.mirrorAcross Plane3d.xy exampleSpline
--> QuadraticSpline3d.fromControlPoints
-->     ( Point3d.fromCoordinates ( 1, 1, -1 )
-->     , Point3d.fromCoordinates ( 3, 2, -1 )
-->     , Point3d.fromCoordinates ( 3, 3, -3 )
-->     )
projectOnto : Plane3d -> QuadraticSpline3d -> QuadraticSpline3d

Find the orthographic projection of a spline onto a plane.

QuadraticSpline3d.projectOnto Plane3d.xy exampleSpline
--> QuadraticSpline3d.fromControlPoints
-->     ( Point3d.fromCoordinates ( 1, 1, 0 )
-->     , Point3d.fromCoordinates ( 3, 2, 0 )
-->     , Point3d.fromCoordinates ( 3, 3, 0 )
-->     )

Coordinate conversions

relativeTo : Frame3d -> QuadraticSpline3d -> QuadraticSpline3d

Take a spline defined in global coordinates, and return it expressed in local coordinates relative to a given reference frame.

localFrame =
    Frame3d.atPoint
        (Point3d.fromCoordinates ( 1, 2, 3 ))


QuadraticSpline3d.relativeTo localFrame exampleSpline
--> QuadraticSpline3d.fromControlPoints
-->     ( Point3d.fromCoordinates ( 0, -1, -2 )
-->     , Point3d.fromCoordinates ( 2, 0, -2 )
-->     , Point3d.fromCoordinates ( 2, 1, 0 )
-->     )
placeIn : Frame3d -> QuadraticSpline3d -> QuadraticSpline3d

Take a spline considered to be defined in local coordinates relative to a given reference frame, and return that spline expressed in global coordinates.

localFrame =
    Frame3d.atPoint
        (Point3d.fromCoordinates ( 1, 2, 3 ))


QuadraticSpline3d.placeIn localFrame exampleSpline
--> QuadraticSpline3d.fromControlPoints
-->     ( Point3d.fromCoordinates ( 2, 3, 4 )
-->     , Point3d.fromCoordinates ( 4, 4, 4 )
-->     , Point3d.fromCoordinates ( 4, 5, 6 )
-->     )

Sketch planes

projectInto : SketchPlane3d -> QuadraticSpline3d -> QuadraticSpline2d

Project a spline into a given sketch plane. Conceptually, finds the orthographic projection of the spline onto the plane and then expresses the projected spline in 2D sketch coordinates.

exampleSpline
    |> QuadraticSpline3d.projectInto SketchPlane3d.yz
--> QuadraticSpline2d.fromControlPoints
-->     ( Point2d.fromCoordinates ( 1, 1 )
-->     , Point2d.fromCoordinates ( 2, 1 )
-->     , Point2d.fromCoordinates ( 3, 3 )
-->     )

Subdivision

bisect : QuadraticSpline3d -> ( QuadraticSpline3d, QuadraticSpline3d )

Split a spline into two roughly equal halves. Equivalent to splitAt 0.5.

QuadraticSpline3d.bisect exampleSpline
--> ( QuadraticSpline3d.fromControlPoints
-->     ( Point3d.fromCoordinates ( 1, 1, 1 )
-->     , Point3d.fromCoordinates ( 2, 2.5 )
-->     , Point3d.fromCoordinates ( 3, 2.5 )
-->     )
--> , QuadraticSpline3d.fromControlPoints
-->     ( Point3d.fromCoordinates ( 3, 2.5 )
-->     , Point3d.fromCoordinates ( 4, 2.5 )
-->     , Point3d.fromCoordinates ( 3, 3, 3 )
-->     )
--> )
Float
-> QuadraticSpline3d
-> ( QuadraticSpline3d, QuadraticSpline3d )

Split a spline at a particular parameter value (in the range 0 to 1), resulting in two smaller splines.

QuadraticSpline3d.splitAt 0.75 exampleSpline
--> ( QuadraticSpline3d.fromControlPoints
-->     ( Point3d.fromCoordinates ( 1, 1, 1 )
-->     , Point3d.fromCoordinates ( 2, 1.5, 1 )
-->     , Point3d.fromCoordinates ( 2.5, 2, 1.5 )
-->     )
--> , QuadraticSpline3d.fromControlPoints
-->     ( Point3d.fromCoordinates ( 2.5, 2, 1.5 )
-->     , Point3d.fromCoordinates ( 3, 2.5, 2 )
-->     , Point3d.fromCoordinates ( 3, 3, 3 )
-->     )
--> )

Arc length parameterization

A spline that has been parameterized by arc length.

arcLengthParameterized : Float -> QuadraticSpline3d -> ArcLengthParameterized

Build an arc length parameterization of the given spline, within a given tolerance. Generally speaking, all operations on the resulting ArcLengthParameterized value will be accurate to within the given arc length tolerance.

tolerance =
    1.0e-4


parameterizedSpline =
    QuadraticSpline3d.arcLengthParameterized
        tolerance
        exampleSpline
arcLength : ArcLengthParameterized -> Float

Find the total arc length of a spline. This will be accurate to within the tolerance given when calling arcLengthParameterized.

arcLength : Float
arcLength =
    QuadraticSpline3d.arcLength parameterizedSpline


arcLength
--> 3.8175
pointAlong : ArcLengthParameterized -> Float -> Maybe Point3d

Try to get the point along a spline at a given arc length. For example, to get the point a quarter of the way along exampleSpline:

QuadraticSpline3d.pointAlong parameterizedSpline
    (arcLength / 4)
--> Just <|
-->     Point3d.fromCoordinates
-->         ( 1.8227, 1.4655, 1.1083 )

Note that this is not the same as evaulating at a parameter value of 1/4:

QuadraticSpline3d.pointOn exampleSpline 0.25
--> Point3d.fromCoordinates ( 1.875, 1.5, 1.125 )

If the given arc length is less than zero or greater than the arc length of the spline, Nothing is returned.

tangentAlong : ArcLengthParameterized -> Float -> Maybe Direction3d

Try to get the tangent direction along a spline at a given arc length. To get the tangent direction a quarter of the way along exampleSpline:

QuadraticSpline3d.tangentAlong parameterizedSpline
    (arcLength / 4)
--> Just <|
-->     Direction3d.with
-->         { azimuth = degrees 33.091
-->         , elevation = degrees 14.260
-->         }

If the given arc length is less than zero or greater than the arc length of the spline (or if the derivative of the spline happens to be exactly zero at the given arc length), Nothing is returned.

arcLengthToParameterValue : ArcLengthParameterized -> Float -> Maybe Float

Try to get the parameter value along a spline at a given arc length. If the given arc length is less than zero or greater than the arc length of the spline, returns Nothing.

QuadraticSpline3d.arcLengthToParameterValue
    parameterizedSpline
    (arcLength / 4)
--> Just 0.2328
parameterValueToArcLength : ArcLengthParameterized -> Float -> Maybe Float

Try to get the arc length along a spline at a given parameter value. If the given parameter value is less than zero or greater than one, returns Nothing.

QuadraticSpline3d.parameterValueToArcLength
    parameterizedSpline
    0.25
--> Just 1.0192

Low level

Low level functionality that you are unlikely to need to use directly.

derivativeMagnitude : QuadraticSpline3d -> Float -> Float

Find the magnitude of the derivative to a spline at a particular parameter value;

QuadraticSpline3d.derivativeMagnitude spline t

is equivalent to

Vector3d.length (QuadraticSpline3d.derivative spline t)

but more efficient since it avoids any intermediate Vector3d allocation.

secondDerivative : QuadraticSpline3d -> Vector3d

Get the second derivative of a spline (for a quadratic spline, this is a constant).