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package clock

import ""

Package clock provides a clock and time functions for a sprite engine.


Package Files

clock.go tween.go


var (
    EaseIn    = CubicBezier(0.42, 0, 1, 1)
    EaseOut   = CubicBezier(0, 0, 0.58, 1)
    EaseInOut = CubicBezier(0.42, 0, 0.58, 1)

Standard tween functions.

Easing means a slowing near the timing boundary, as defined by a cubic bezier curve. Exact parameters match the CSS properties.

func CubicBezier Uses

func CubicBezier(x0, y0, x1, y1 float32) func(t0, t1, t Time) float32

CubicBezier generates a tween function determined by a Cubic Bézier curve.

The parameters are cubic control parameters. The curve starts at (0,0) going toward (x0,y0), and arrives at (1,1) coming from (x1,y1).

func Linear Uses

func Linear(t0, t1, t Time) float32

Linear computes the fraction [0,1] that t lies between [t0,t1].

type Time Uses

type Time int32

A Time represents an instant in sprite time.

The application using the sprite engine is responsible for determining sprite time.

Typically time 0 is when the app is initialized and time is quantized at the intended frame rate. For example, an app may record wall time when it is initialized

var start = time.Now()

and then compute the current instant in time for 60 FPS:

now := clock.Time(time.Since(start) * 60 / time.Second)

An application can pause or reset sprite time, but it must be aware of any stateful sprite.Arranger instances that expect time to continue.

Package clock is imported by 13 packages. Updated 2017-08-16. Refresh now. Tools for package owners.