A Vector2d represents a quantity such as a displacement or velocity in 2D, and is defined by its X and Y components. This module contains a variety of vector-related functionality, such as

• Adding or subtracting vectors
• Finding the lengths of vectors
• Rotating vectors
• Converting vectors between different coordinate systems

Note that unlike in many other geometry packages where vectors are used as a general-purpose data type, elm-geometry has separate data types for vectors, directions and points. In most code it is actually more common to use Point2d and Direction2d than Vector2d, and much code can avoid working directly with Vector2d values at all!

Constants

Although there are no predefined constants for the vectors with components (1, 0) and (0, 1), in most cases you will actually want their Direction2d versions Direction2d.x and Direction2d.y.

Constructors

Properties

Comparison

Measurement

Arithmetic

Transformations

Note that for mirrorAcross and projectOnto, only the direction of the axis affects the result, since vectors are position-independent. Think of mirroring/projecting a vector across/onto an axis as moving the vector so its tail is on the axis, then mirroring/projecting its tip across/onto the axis.

Coordinate conversions

Like other transformations, coordinate conversions of vectors depend only on the orientations of the relevant frames, not the positions of their origin points.