2 replies to this topic

[N1ghtDr34m3r]

Hey guys.

I'm currently coding a little game with the libGdx library and I wanted to have a slight fade in/fade out effect if the screen changes (e.g. from MainMenu into the game).
After some time, I've got the idea, that I draw a black filled rectangle over the whole screen with an increasing alpha value. At the point where the alpha value is 0.0f (so, the whole screen is black) I change the screen to my game, where at this point my alpha value is getting bigger (so it will be transparent more and more).

So I implemented something like this:

// init
Gdx.gl.glEnable( GL10.GL_ALPHA_TEST );
// [...]
// render
Gdx.gl10.glAlphaFunc( GL10.GL_GREATER, 0 );
// render my quad

While having my project setting up with LwjglApplicationConfig.useGL20 = false; it will work very well.
But enabling gl20, it won't start, saying that there is a problem with GL10.GL_ALPHA_TEST
So I searched if gl20 have something like that... but now it's 30 minutes later and I don't have any solution.

Could you help?
What I have to enable in gl20 ( and setting up) to use alpha like in gl10 ?

Greets,
N1ghtDr34m3r

[karwosts]

The built in alphaFunc is gone in GL20 because you're expected to replicate it in shader with the 'discard' keyword.

Basically at some point in your fragment shader you'll have:

float alphaMin = 0.1;
if(color.a < alphaMin) { discard; }

This achieves the same effect as alpha testing.

[N1ghtDr34m3r]

Oh... I'm so a badass boy, I don't use gl20 with a shader. xD
Thank you very much. Now I know what I will google later. ;-)

"Thread.join()"
^^