elm-geometry
is an Elm package for working with 2D and
3D geometry. It provides a wide variety of geometric data types such as points,
vectors, arcs, spline curves and coordinate frames, along with functions for
transforming and combining them in many different ways. You can:
- Rotate points around axes in 3D
- Mirror triangles across 3D planes
- Project 3D geometry into 2D sketch planes
- Measure distances and angles between different objects
- Convert objects between different coordinate systems
- Compose complex 2D/3D transformations
- ...and much more!
A wide variety of data types are supported:
-
Point2d
,Point3d
,Vector2d
,Vector3d
,Direction2d
,Direction3d
-
Axis2d
,Axis3d
,Plane3d
-
Frame2d
,Frame3d
,SketchPlane3d
-
BoundingBox2d
,BoundingBox3d
-
LineSegment2d
,LineSegment3d
,Triangle2d
,Triangle3d
-
Polyline2d
,Polyline3d
,Polygon2d
-
Circle2d
,Circle3d
,Arc2d
,Arc3d
-
Ellipse2d
,EllipticalArc2d
-
QuadraticSpline2d
,QuadraticSpline3d
,CubicSpline2d
,CubicSpline3d
A large range of geometric functionality is included, such as various forms of constructors...
Point3d.fromCoordinates ( 1, 4, 5 )
Direction2d.fromAngle (degrees 30)
Point3d.midpoint p1 p2
Vector2d.withLength 3 Direction2d.y
Triangle2d.fromVertices ( p1, p2, p3 )
-- fit a plane through three points
Plane3d.throughPoints p1 p2 p3
Axis3d.through Point3d.origin Direction3d.z
Arc2d.from p1 p2 (degrees 90)
QuadraticSpline3d.with
{ startPoint = p1
, controlPoint = p2
, endPoint = p3
}
CubicSpline2d.fromEndpoints
{ startPoint = p1
, startDerivative = v1
, endPoint = p2
, endDerivative = v2
}
...point/vector arithmetic...
Vector3d.sum v1 v2
-- the vector from the point p1 to the point p2
Vector2d.from p1 p2
Vector3d.crossProduct v1 v2
Vector2d.length vector
-- distance of a point from the origin point (0, 0)
point |> Point2d.distanceFrom Point2d.origin
...2D/3D transformations...
Vector2d.rotateBy (degrees 45) vector
Point2d.rotateAround Point2d.origin (degrees 45) point
Point3d.mirrorAcross Plane3d.xy point
Vector3d.projectionIn Direction3d.z vector
Triangle3d.rotateAround Axis3d.x (degrees 45) triangle
lineSegment
|> LineSegment3d.mirrorAcross Plane3d.yz
|> LineSegment3d.projectOnto Plane3d.xy
Plane3d.offsetBy 3 Plane3d.xy
...and conversions between coordinate systems:
rotatedFrame =
Frame2d.atOrigin |> Frame2d.rotateBy (degrees 30)
-- convert from global coordinates to local coordinates
-- (relative to the given coordinate frame)
Vector2d.relativeTo rotatedFrame vector
-- convert from local coordinates (relative to the given
-- coordinate frame) to global coordinates
Point2d.placeIn rotatedFrame point
-- convert from global 3D coordinates to local 2D
-- coordinates in the given sketch plane
point2d =
Point3d.projectInto SketchPlane3d.yz point3d
-- convert from local 2D coordinates in the given
-- sketch plane back to global 3D coordinates
point3d =
Point3d.on SketchPlane3d.yz point2d
Assuming you have installed Elm and
started a new project, you can install elm-geometry
by running
elm install ianmackenzie/elm-geometry
in a command prompt inside your project directory.
Full API documentation
is available for each module. Most modules are associated with a particular data
type (for example, the Point3d
module contains functions for creating and manipulating Point3d
values).
Following the Elm package design guidelines,
most elm-geometry
modules are designed to be imported exposing only the
corresponding types, and using the module name as a prefix for everything else:
import Point3d exposing (Point3d)
import Axis3d exposing (Axis3d)
rotatedPoint : Point3d
rotatedPoint =
Point3d.rotateAround Axis3d.x (degrees 30) originalPoint
Please open a new issue
if you run into a bug, if any documentation is missing/incorrect/confusing, or
if there's a new feature that you would find useful. For general questions about
using elm-geometry
, the best place is probably the #geometry channel on
the friendly Elm Slack:
You can also try:
- Sending me (@ianmackenzie) a message on Slack - even if you don't have any particular questions right now, it would be great to know what you're hoping to do with the package!
- Posting to the Elm Discourse forums
- Or if you happen to be in the New York area, come on out to the Elm NYC meetup =)
You can also find me on Twitter (@ianemackenzie),
where I occasionally post elm-geometry
-related stuff like demos or new
releases. Have fun, and don't be afraid to ask for help!