OpenSolid.Frame3d

Frame3d

A Frame3d has an origin point and a set of X, Y and Z directions (which are always perpendicular to each other). It can be thought of as:

A local coordinate system: Most geometric types have associated relativeTo and placeIn functions that convert values of that type from global coordinates to local coordinates in a particular frame, and vice versa.
A set of axes and planes: It is often convenient to (for example) rotate around the Z axis of a frame, or mirror across its XY plane. Frames can also themselves be translated, rotated and mirrored!
A combined 3D position and orientation: For example, a Frame3d could be used to define the position and orientation of a spaceship in a 3D game. Movement of the ship would then be done by translating and rotating the frame.

Frames can by constructed by passing a record with originPoint, xDirection, yDirection and zDirection fields to the Frame3d constructor, for example:

frame =
    Frame3d
        { originPoint = Point3d ( 2, 1, 3 )
        , xDirection = Direction3d ( 0.8, 0.6, 0 )
        , yDirection = Direction3d ( -0.6, 0.8, 0 )
        , zDirection = Direction3d ( 0, 0, 1)
        }

In this case you must be careful to ensure that the X, Y and Z directions are perpendicular. (You will likely also want to make sure that they form a right-handed coordinate system.)

Predefined frames

xyz : Frame3d

The global XYZ frame.

Frame3d.xyz
--> Frame3d
-->     { originPoint = Point3d.origin
-->     , xDirection = Direction3d.x
-->     , yDirection = Direction3d.y
-->     , zDirection = Direction3d.z
-->     }

Constructors

at : Point3d -> Frame3d

Construct a frame aligned with the global XYZ frame but with the given origin point.

Frame3d.at (Point3d ( 2, 1, 3 ))
--> Frame3d
-->     { originPoint = Point3d ( 2, 1, 3 )
-->     , xDirection = Direction3d.x
-->     , yDirection = Direction3d.y
-->     , zDirection = Direction3d.z
-->     }

Accessors

originPoint : Frame3d -> Point3d

Get the origin point of a given frame.

Frame3d.originPoint Frame3d.xyz
--> Point3d.origin

xDirection : Frame3d -> Direction3d

Get the X direction of a given frame.

Frame3d.xDirection Frame3d.xyz
--> Direction3d.x

yDirection : Frame3d -> Direction3d

Get the Y direction of a given frame.

Frame3d.yDirection Frame3d.xyz
--> Direction3d.y

zDirection : Frame3d -> Direction3d

Get the Z direction of a given frame.

Frame3d.zDirection Frame3d.xyz
--> Direction3d.z

Axes

xAxis : Frame3d -> Axis3d

Get the X axis of a given frame (the axis formed from the frame's origin point and X direction).

Frame3d.xAxis Frame3d.xyz
--> Axis3d.x

yAxis : Frame3d -> Axis3d

Get the Y axis of a given frame (the axis formed from the frame's origin point and Y direction).

Frame3d.yAxis Frame3d.xyz
--> Axis3d.y

zAxis : Frame3d -> Axis3d

Get the Z axis of a given frame (the axis formed from the frame's origin point and Z direction).

Frame3d.zAxis Frame3d.xyz
--> Axis3d.z

Planes

The following functions all return planes with the same origin point as the given plane, but with varying normal directions. In each case the normal direction of the resulting plane is given by the cross product of the two indicated basis directions (assuming a right-handed frame); for example,

Frame3d.xyPlane Frame3d.xyz
--> Plane3d
-->     { originPoint = Point3d.origin
-->     , normalDirection = Direction3d.z
-->     }

since the cross product of the X and Y basis directions of a frame is equal to its Z basis direction. And since reversing the order of arguments in a cross product reverses the sign of the result,

Frame3d.yxPlane Frame3d.xyz
--> Plane3d
-->     { originPoint = Point3d.origin
-->     , normalDirection = Direction3d.flip Direction3d.z
-->     }

xyPlane : Frame3d -> Plane3d

Get a plane with normal direction equal to the frame's positive Z direction.

yxPlane : Frame3d -> Plane3d

Get a plane with normal direction equal to the frame's negative Z direction.

yzPlane : Frame3d -> Plane3d

Get a plane with normal direction equal to the frame's positive X direction.

zyPlane : Frame3d -> Plane3d

Get a plane with normal direction equal to the frame's negative X direction.

zxPlane : Frame3d -> Plane3d

Get a plane with normal direction equal to the frame's positive Y direction.

xzPlane : Frame3d -> Plane3d

Get a plane with normal direction equal to the frame's negative Y direction.

Sketch planes

These functions all form a SketchPlane3d from two axes of the given frame. The X and Y axes of the sketch plane will correspond to the two indicated axes. For example,

Frame3d.yzSketchPlane Frame3d.xyz
--> SketchPlane3d
-->     { originPoint = Point3d.origin
-->     , xDirection = Direction3d.y
-->     , yDirection = Direction3d.z
-->     }

Note that this can be confusing - for example, a local X coordinate in the above sketch plane corresponds to a global Y coordinate, and a local Y coordinate corresponds to a global Z coordinate!

xySketchPlane : Frame3d -> SketchPlane3d

Form a sketch plane from the given frame's X and Y axes.

yxSketchPlane : Frame3d -> SketchPlane3d

Form a sketch plane from the given frame's Y and X axes.

yzSketchPlane : Frame3d -> SketchPlane3d

Form a sketch plane from the given frame's Y and Z axes.

zySketchPlane : Frame3d -> SketchPlane3d

Form a sketch plane from the given frame's Z and Y axes.

zxSketchPlane : Frame3d -> SketchPlane3d

Form a sketch plane from the given frame's Z and X axes.

xzSketchPlane : Frame3d -> SketchPlane3d

Form a sketch plane from the given frame's X and Z axes.

Transformations

flipX : Frame3d -> Frame3d

Reverse the X direction of a frame.

Frame3d.flipX Frame3d.xyz
--> Frame3d
-->     { originPoint = Point3d.origin
-->     , xDirection = Direction3d.flip Direction3d.x
-->     , yDirection = Direction3d.y
-->     , zDirection = Direction3d.z
-->     }

flipY : Frame3d -> Frame3d

Reverse the Y direction of a frame.

Frame3d.flipY Frame3d.xyz
--> Frame3d
-->     { originPoint = Point3d.origin
-->     , xDirection = Direction3d.x
-->     , yDirection = Direction3d.flip Direction3d.y
-->     , zDirection = Direction3d.z
-->     }

flipZ : Frame3d -> Frame3d

Reverse the Z direction of a frame.

Frame3d.flipZ Frame3d.xyz
--> Frame3d
-->     { originPoint = Point3d.origin
-->     , xDirection = Direction3d.x
-->     , yDirection = Direction3d.y
-->     , zDirection = Direction3d.flip Direction3d.z
-->     }

moveTo : Point3d -> Frame3d -> Frame3d

Move a frame so that it has the given origin point but same orientation.

point =
    Point3d ( 2, 1, 3 )


Frame3d.at point
--> Frame3d
-->     { originPoint = Point3d ( 2, 1, 3 )
-->     , xDirection = Direction3d.x
-->     , yDirection = Direction3d.y
-->     , zDirection = Direction3d.z
-->     }

rotateAround : Axis3d -> Float -> Frame3d -> Frame3d

Rotate a frame around an axis by a given angle (in radians). The frame's origin point and basis directions will all be rotated around the given axis.

frame =
    Frame3d.at (Point3d ( 2, 1, 3 ))


Frame3d.rotateAround Frame3d.zAxis (degrees 90) frame
--> Frame3d
-->     { originPoint = Point3d ( -1, 2, 3 )
-->     , xDirection = Direction3d.y
-->     , yDirection = Direction3d.flip Direction3d.x
-->     , zDirection = Direction3d.z
-->     }

rotateAroundOwn : (Frame3d -> Axis3d) -> Float -> Frame3d -> Frame3d

Rotate a frame around one of its own axes by a given angle (in radians).

The first argument is a function that returns the axis to rotate around, given the current frame. The majority of the time this will be either Frame3d.xAxis, Frame3d.yAxis or Frame3d.zAxis. Compare the following to the above example for rotateAround:

frame =
    Frame3d.at (Point3d ( 2, 1, 3 ))


Frame3d.rotateAroundOwn Frame3d.zAxis (degrees 90) frame
--> Frame3d
-->     { originPoint = Point3d ( 2, 1, 3 )
-->     , xDirection = Direction3d.y
-->     , yDirection = Direction3d.flip Direction3d.x
-->     , zDirection = Direction3d.z
-->     }

Since the rotation is done around the frame's own Z axis (which passes through the frame's origin point), the origin point remains the same after rotation.

In this example the frame's Z axis has the same orientation as the global Z axis so the frame's basis directions are rotated the same way, but in more complex examples involving rotated frames a rotation around (for example) the frame's own Z axis may be completely different from a rotation around the global Z axis.

translateBy : Vector3d -> Frame3d -> Frame3d

Translate a frame by a given displacement.

frame =
    Frame3d.at (Point3d ( 2, 1, 3 ))


displacement =
    Vector3d ( 1, 1, 1 )


Frame3d.translateBy displacement frame
--> Frame3d.at (Point3d ( 3, 2, 4 ))

translateAlongOwn : (Frame3d -> Axis3d) -> Float -> Frame3d -> Frame3d

Translate a frame along one of its own axes by a given distance.

The first argument is a function that returns the axis to translate along, given the current frame. The majority of the time this will be either Frame3d.xAxis, Frame3d.yAxis or Frame3d.zAxis.

This function is convenient when constructing frames via a series of transformations. For example,

Frame3d.at (Point3d ( 2, 0, 0 ))
    |> Frame3d.rotateAroundOwn Frame3d.zAxis (degrees 45)
    |> Frame3d.translateAlongOwn Frame3d.xAxis 2

means "construct a frame at the point (2, 0, 0), rotate it around its own Z axis by 45 degrees, then translate it along its own (rotated) X axis by 2 units", resulting in

Frame3d
    { originPoint = Point3d ( 3.4142, 1.4142, 0 )
    , xDirection = Direction3d ( 0.7071, 0.7071, 0 )
    , yDirection = Direction3d ( -0.7071, 0.7071, 0)
    , zDirection = Direction3d.z
    }

mirrorAcross : Plane3d -> Frame3d -> Frame3d

Mirror a frame across a plane.

frame =
    Frame3d.at (Point3d ( 2, 1, 3 ))


Frame3d.mirrorAcross Plane3d.xy frame
--> Frame3d
-->     { originPoint = Point3d ( 2, 1, -3 )
-->     , xDirection = Direction3d.x
-->     , yDirection = Direction3d.y
-->     , zDirection = Direction3d.flip Direction3d.z
-->     }

Note that this will switch the handedness of the frame.

Coordinate frames

relativeTo : Frame3d -> Frame3d -> Frame3d

Take two frames defined in global coordinates, and return the second one expressed in local coordinates relative to the first.

placeIn : Frame3d -> Frame3d -> Frame3d

Take one frame defined in global coordinates and a second frame defined in local coordinates relative to the first frame, and return the second frame expressed in global coordinates.

opensolid/geometry/1.0.0