Engine API Reference - v2.23.0-beta.17
    Preparing search index...

    Class Curve

    A curve is a collection of keys (time/value pairs). The shape of the curve is defined by its type that specifies an interpolation scheme for the keys.

    Keys are kept sorted by time. Supply them to the constructor as a flat [time, value, ...] array or insert them one at a time with add, then evaluate the curve at any time with value. The type selects how values between keys are computed: CURVE_LINEAR, CURVE_SMOOTHSTEP, CURVE_SPLINE or CURVE_STEP. Curves drive values that change over time or over a normalized range, such as particle size over a particle's lifetime.

    // Ease a value in over one second and read it back a quarter of the way through
    const curve = new Curve([0, 0, 1, 1]);
    curve.type = CURVE_SMOOTHSTEP;
    const v = curve.value(0.25);
    Index
    constructor
    keys tension type
    length
    add clear clone closest get remove sort value

    • Creates a new Curve instance.

      Parameters

      • Optionaldata: number[]

        An array of keys (pairs of numbers with the time first and value second).

      Returns Curve

      const curve = new Curve([
          0, 0,        // At 0 time, value of 0
          0.33, 2,     // At 0.33 time, value of 2
          0.66, 2.6,   // At 0.66 time, value of 2.6
          1, 3         // At 1 time, value of 3
      ]);
    keys: number[][] = []

    The keys that define the curve. Each key is an array of two numbers with the time first and the value second.

    tension: number = 0.5

    Controls how CURVE_SPLINE tangents are calculated. Valid range is between 0 and 1 where 0 results in a non-smooth curve (equivalent to linear interpolation) and 1 results in a very smooth curve. Use 0.5 for a Catmull-Rom spline.

    type: number = CURVE_SMOOTHSTEP

    The curve interpolation scheme. Can be:

    Defaults to CURVE_SMOOTHSTEP.

    • get length(): number

      Gets the number of keys in the curve.

      Returns number

    • Adds a new key to the curve.

      Parameters

      • time: number

        Time to add new key.

      • value: number

        Value of new key.

      Returns number[]

      The newly created [time, value] pair.

      const curve = new Curve();
      curve.add(0, 1);   // add key at time 0 with value 1
      curve.add(1, 2);   // add key at time 1 with value 2

    • Removes all keys from the curve.

      Returns Curve

      The curve instance.

      const curve = new Curve([0, 1, 1, 2]);
      curve.clear(); // curve now has no keys

    • Returns a clone of the specified curve object.

      Returns Curve

      A clone of the specified curve.

      const curve = new Curve([0, 0, 1, 10]);
      const clonedCurve = curve.clone();

    • Returns the key closest to the specified time.

      Parameters

      • time: number

        The time to find the closest key to.

      Returns number[] | null

      The [time, value] pair closest to the specified time, or null if no keys exist.

      const curve = new Curve([0, 1, 0.5, 2, 1, 3]);
      const key = curve.closest(0.6); // returns [0.5, 2]

    • Gets the [time, value] pair at the specified index.

      Parameters

      • index: number

        The index of key to return.

      Returns number[]

      The [time, value] pair at the specified index.

      const curve = new Curve([0, 1, 1, 2]);
      const key = curve.get(0); // returns [0, 1]

    • Removes the key at the specified index.

      Parameters

      • index: number

        The index of the key to remove.

      Returns number[] | null

      The removed [time, value] pair, or null if the index is out of range.

      const curve = new Curve([0, 1, 1, 2]);
      curve.remove(0); // removes the key at time 0

    • Returns the interpolated value of the curve at specified time.

      Parameters

      • time: number

        The time at which to calculate the value.

      Returns number

      The interpolated value.

      const curve = new Curve([0, 0, 1, 10]);
      const value = curve.value(0.5); // returns interpolated value at time 0.5

    Settings
    Member Visibility

    On This Page
    Constructors
    Properties
    Accessors
    Methods