Helper functions

Various helper functions and types that are used throughout this package. Some of these functions might be useful when you’re creating your own components, especially ones that use rotation.

Constants

TAU

Defined as 2π, useful when working with radians.

Functions

clamp

declare const clamp: (value: Nullable<number>, min: number, max: number) => number;

• Returns value if it is between minValue and maxValue;
• Returns minValue if value is a number smaller than minValue, null, or undefined;
• Returns maxValue if value is larger than maxValue

normalisedAngle

declare const normalisedAngle: (angle: number) => number;

angle is an angle in radians, possibly negative, and returns a normalised angle in radians, where 0 ≤ angle ≥ 2π.

angleToValue

declare function angleToValue(
  angle: number,
  minValue: number,
  maxValue: number,
  minAngle: number,
  maxAngle: number,
): number;

Converts angle in radians to a value by linear mapping from the range minAngle - maxAngle to minValue - maxValue.

valueToAngle

declare function valueToAngle(
  value: number,
  minValue: number,
  maxValue: number,
  minAngle: number,
  maxAngle: number,
): number;

Maps value, and returns a corresponding angle in radians, by linear mapping from minValue - maxValue to minAngle - maxAngle.

angleToPoint

declare function angleToPoint(angle: number, origin: Point2D, radius: number): Point2D;

Takes angle in radians between 0-2π, radius as the radius of a circle with center origin, and returns the point {x, y} that lies on the circle and a line from the origin at angle. Examples:

angletoPoint(0, { x: 0, y: 0 }, 1); // returns {x:1, y:0 }
angletoPoint((5 / 8) * Math.PI, { x: 0, y: 0 }, 1); // returns {x:-0.7071, y:-0.7071 }

pointToAngle

declare function pointToAngle(point: Point2D, origin: Point2D): number;

Returns the angle in radians of a vector from origin to point. Example:

pointToAngle({ x: -0.7071, y: 0.7071 }, { x: 0, y: 0 }); // returns 1.1781 == 3/8 * Math.PI

pointEquals

declare function pointEquals(point: Nullable<Point2D>, otherPoint: Nullable<Point2D>): boolean;

Returns true if point and otherPoint have equal x and y coordinates, or if both points are null.

isPointInRect

declare const isPointInRect: (point: Point2D, rect: Nullable<DOMRect>) => boolean;

Returns true if point is within rectangle rect (inclusive). Returns false if rect is null or undefined.

rad2deg

declare const rad2deg: (radians: number) => number;

Converts radians to degrees, which is useful for CSS transforms.

deg2rad

declare const deg2rad: (degrees: number) => number;

Converts degrees to radians.