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CurveKey

A CurveKey represents a key point on a SimpleCurve, providing a value for a specific point in time on that curve. Additional properties may be used to control the shape of that curve.

Constructors

Constructor Name Return Type Description Tags
CurveKey.New() CurveKey Constructs a new CurveKey. None
CurveKey.New(number time, number value, [table optionalParameters]) CurveKey Constructs a CurveKey with the given time and value. An optional table may be provided to override the following parameters:
interpolation (CurveInterpolation): Sets the interpolation property of the curve key. Defaults to CurveInterpolation.LINEAR.
arriveTangent (number): Sets the arriveTangent property of the curve key. Defaults to 0.
leaveTangent (number): Sets the leaveTangent property of the curve key. Defaults to 0.
tangent (number): Sets both the arriveTangent and leaveTangent properties of the curve key. It is an error to specify arriveTangent or leaveTangent if tangent is provided.		 None
CurveKey.New(CurveKey other) CurveKey Makes a copy of the given CurveKey. None

Properties

Property Name Return Type Description Tags
interpolation CurveInterpolation The interpolation mode between this curve key and the next. Read-Write
time number The time at this curve key. Read-Write
value number The value at this curve key. Read-Write
arriveTangent number The arriving tangent at this key when using cubic interpolation. Read-Write
leaveTangent number The leaving tangent at this key when using cubic interpolation. Read-Write

Examples

Example using:

New

interpolation

time

value

In this example, we track the position of the player and draw a line to represent their movement path. Although we only save the player's position every 0.3 seconds, we are able to draw a much smoother path thanks to the SimpleCurve data type. At runtime we construct three SimpleCurves, one for each of player's dimensions of movement: X, Y, and Z. The curves are built with a small set of points, but can estimate the in-between values with the GetValue() function.

local PLAYER = Game.GetLocalPlayer()
local MAX_POINTS = 30
local TIME_PERIOD = 0.3
local DRAW_RESOLUTION = 0.02

local lastPosition = PLAYER:GetWorldPosition()

local positions = {}
local curveX, curveY, curveZ

function Tick()
    Task.Wait(TIME_PERIOD)

    local pos = PLAYER:GetWorldPosition()
    if lastPosition ~= pos then
        lastPosition = pos

        table.insert(positions, pos)

        if #positions > MAX_POINTS then
            table.remove(positions, 1)
        end

        RebuildCurves()
    end
    DrawDebug()
end

function RebuildCurves()
    local keysX = {}
    local keysY = {}
    local keysZ = {}

    local t = 0
    local key
    for i,pos in ipairs(positions) do
        key = CurveKey.New()
        key.interpolation = CurveInterpolation.CUBIC
        key.time = t
        key.value = pos.x
        table.insert(keysX, key)

        key = CurveKey.New()
        key.interpolation = CurveInterpolation.CUBIC
        key.time = t
        key.value = pos.y
        table.insert(keysY, key)

        key = CurveKey.New()
        key.interpolation = CurveInterpolation.CUBIC
        key.time = t
        key.value = pos.z
        table.insert(keysZ, key)

        t = t + TIME_PERIOD
    end

    curveX = SimpleCurve.New(keysX)
    curveY = SimpleCurve.New(keysY)
    curveZ = SimpleCurve.New(keysZ)
end

function DrawDebug()
    local drawParams = {duration = TIME_PERIOD+0.1, thickness = 3}
    local prevPoint = nil

    local t = curveX.minTime
    while t <= curveX.maxTime do
        local point = Vector3.New(
            curveX:GetValue(t),
            curveY:GetValue(t),
            curveZ:GetValue(t)
        )
        if prevPoint ~= nil then
            CoreDebug.DrawLine(prevPoint, point, drawParams)
        end
        prevPoint = point

        t = t + DRAW_RESOLUTION
    end
end

See also: SimpleCurve.New | CoreDebug.DrawLine | Game.GetLocalPlayer | Player.GetWorldPosition | Task.Wait

Last update: February 2, 2022