A Direction3d represents a direction like 'up' or 'north' or 'forwards'. They are represented using X, Y and Z components, and can be converted to vectors if necessary, but should be thought of as conceptually different. Directions have several uses, such as:

• Constructing a vector from a length and direction
• Determining the component of a vector in a particular direction (for example, finding the component of velocity in the up direction to get vertical speed)
• Determining the angle between two directions
• Defining the orientation of an axis, plane or reference frame

Constants

Constructors

Properties

Comparison

Measurement

Conversion

Transformations

Coordinate conversions

Like other transformations, coordinate transformations of directions depend only on the orientations of the relevant frames, not their positions.