tween

README

tween

Golang animation package.

Developer's Guide

The file curves/ease.go is auto-generated using the following command in the project root directory:

go generate ./...

If you want to make changes to the ease functions edit curves/gen/gen.go and re-run "go generate".

Documentation

Index

• type Engine
  • func NewEngine(duration time.Duration, transition TransitionFunc, updater Updater) *Engine
  • func (e *Engine) Start()
  • func (e *Engine) Stop()
• type Frame
• type TransitionFunc
• type Updater

Types

type Engine

type Engine struct {
	Duration   time.Duration  // The total duration of the tween.
	Framerate  int            // The number of tween data points per second (defaults to 60 fps - like the real gamers use).
	Transition TransitionFunc // Transition calculates the transition curve for the tween.
	Updater    Updater        // Updater updates the tween values for each frame.
	// contains filtered or unexported fields
}

Engine runs a tween relying on transitioner and updater.

func NewEngine

func NewEngine(duration time.Duration, transition TransitionFunc, updater Updater) *Engine

NewEngine creates a basic tween Engine with a framerate of 60fps.

func (*Engine) Start

func (e *Engine) Start()

Start begins the tween running.

func (*Engine) Stop

func (e *Engine) Stop()

Stop terminates the tween immediately.

type Frame

type Frame struct {
	Completed    float64       // Completed is the percentage 0.0 - 1.0 of elapsed time.
	Transitioned float64       // Transitioned is the percentage 0.0 - 1.0 of transition between start and end values of the tween.
	Index        int           // Index is the current frame index
	Elapsed      time.Duration // Elapsed is the current elapsed time in the tween.
}

Frame captures information about the current "frame" of a tween transition.

type TransitionFunc

type TransitionFunc func(completed float64) float64

TransitionFunc calculates the percentage of the transition between the start and end values based tween (elapsed time) completion status. For example, a linear tween simply has a 1:1 ratio between completed and transition percentages and returns the completed value unchanged. An "ease in" transition may create a logorithmic relationship between the completion time and transition value for the first third, then a linear relationship for the remainder.

type Updater

type Updater interface {
	// Start signals the beginning of a tween and is sent before the tweening
	// begins. Start may be used to setup or pre-calculate updates.
	//
	// framerate is the number of frames per second in the tween
	// frames is the total number of frames that be generated
	// frameTime is the duration for each frame
	// runningTime is the total duration for the entire tween
	Start(framerate, frames int, frameTime, runningTime time.Duration)
	// Update receives information about the current Tween Frame and should be
	// used to update output or state.
	Update(Frame Frame)
	// End signals the end of the tween and is called after all updates.
	// End may be used to clean up resources (e.g. update channels).
	End()
}

Updater is the interface for updating the current value as it tweens between start and end values of a Tween.