[SOLVED] Libgdx - Delta Time -> Fade-In Effect

Newbie & Debugging Questions
#1

Hi Guys…
Im having a bit of difficult to come with an idea about this :

A) The image keeps fading out… in 4 seconds, it should be completely black.

B)The image then fades in, in 4 seconds, it should be completely opaque again.

Problem is… DeltaTime…

How do i calculate it properly?
This works perfectly for 4 seconds at 60 fps,
But what if a variation happens? If it was fixed, i would know how-to, but it can goes to 1/30 then 1/45 then 1/60… etc… thats what i dont get it…

Any math tip or code tip, is appreciated. I know i was supposed to know this, but im kinda confused…

Thanks a lot in advance guys and girls? :slight_smile:

if (!fadeSparkle) {

                alpha = alpha - (0.25f) / (1f/delta);
                System.out.println("Fade Out! Alpha = " + alpha);
                player.getCurrent_Level().batch.setColor(1, 1, 1, alpha);
                player.getCurrent_Level().renderer.getSpriteBatch().setColor(1, 1, 1, alpha);

                if (alpha <= 0) {
                    fadeSparkle = true;
                }

            } else {
                alpha = alpha + (0.25f) / (1f/delta);
                 System.out.println("Fade In! Alpha = " + alpha);
                player.getCurrent_Level().batch.setColor(1, 1, 1, alpha);
                player.getCurrent_Level().renderer.getSpriteBatch().setColor(1, 1, 1, alpha);
                if (alpha >= 1) {
                    sparkled = true;
                }
            }