使用libgdx，sin和java淡入淡出

Question

I'm trying to create a function that make fadein and fadeout.

I start using Math.sin() and batch.setColor() to fade the images to black, I don't know that this is the best approach but my idea is running a sin function.

I know that with sin function I can control my fadein/fideout time but I have 2 big problems:

1. I need to start counting when senofloat == 0 and stop when its 1 or start on 1 and stop on 0 for fadeout,
2. I need control the number of times the cycles repeats, example 1 time for fade in 1 time for fade out

tempo is a global variable and

tempo = Gdx.graphics.getDeltaTime();

This is what I have on the render function:

float periudo=2;
float escala = 1;

senofloat = (float) (Math.sin(tempo*2*Math.PI/periudo)*(escala/2) + (escala/2));
batch.setColor(1, 1, 1, senofloat); 

tempo++;

Am I complicating this too much? Is there an easier approach?

Answer 1

You can do this with Scene2D actions.

private Actor actionManager = new Actor(); //use a Stage instead if using one anyway
private final Color fadeColor = new Color ();
private static final Color FADED = new Color(1,1,1,0);

private void fadeOut (float duration){
    ColorAction colorAction = Actions.color(FADED, duration, Interpolation.sine);
    colorAction.setColor(fadeColor);
    actionManager.addAction(colorAction);
}

private void fadeIn (float duration){
    ColorAction colorAction = Actions.color(Color.WHITE, duration, Interpolation.sine);
    colorAction.setColor(fadeColor);
    actionManager.addAction(colorAction);
}

public void render (){
    //...

    actionManager.act(Gdx.graphics.getDeltaTime());
    batch.setColor(fadeColor);
    //...
}

Call fadeOut or fadeIn to start a fade. You can change the Interpolation type to Interpolation.fade if you want. I think it looks better than sine for a color fade.

Answer 2

Best option and easier approach would be using universal-tween-engine

very easy to use and effective as it comes from Aurelien Ribon