Develop Reference

Android OpenGL gameloop outside onDrawFrame

I've got a problem with creating gameloop for my first game. I've read a lot about it but still can't figure it out. It's based on OpenGL so I've used onDrawFrame as a game loop and it works fine on my phone. Problem is that onDrawFrame is refresh time depends on hardware so it runs way too fast on some devices. So what I want is adding a separate game loop that will refresh itself at constant period of time on all smartphones. (and onDrawFrame will only take care of graphics as it should)
As for now I have:
myGameRenderer class with all openGl stuff an onDrawFrame
myGLSurfaceView that supports touch events
myGameActivity
onDrawFrame activates myGameUpdate function that controls changing positions of all objects in game depending on info from myGLSurfaceView
I've tried with creating new Runnable but it doesn't seem to work, I can't figure out how to start that runnable and where i should place it (I've tried to place it in myGameRenderer class, but it didn't seem to work, nothing was moving:
private final Runnable mUpdateDisplay = new Runnable() {
#Override
public void run() {
update();
}};
private void update() {
//some update stuff blablabla
//some update stuff blablabla
mHandler.postDelayed(mUpdateDisplay,40); //to refresh at 25 fps
}
but I guess I don't get the idea of it - I mean I create this runnable.
I've tried to place it in onCreateSurface to start it but no effect.
So - is the generall idea ok? And how to start the loop? Where to place it? Or should I use any other way?

Ok it was simple - I was just missing r.run();
But as allways there's something. Now it works as i wanted - I mean frames doesn't depend on hardware, but everything is not as smooth as it was - and part of objects in 3d are flickering. Seems like some objects visibly are drawn faster, some later and it looks ugly.
So what am I doing wrong? Is there a better way?

how to create loading screen in libgdx?

I have a GameScreen class that renders my game.
but before starting to render the game, it needs to reading files and initializing that is time consuming.
So I need to show/render another Screen class called LoadingScreen in order to spending some time and concurrently read my files and do initializing process for my GameScreen, and after initializing completed changing the screen by calling setScreen(gameScreen).
I need to use thread for making this concurrent work, now the problem is that if I use a thread to read files and initializing; When switching to the GameScreen the openGl gives me this error:
javax.media.opengl.GLException: Error: no OpenGL buffer object appears to be bound to target 0x8892
at com.sun.opengl.impl.GLBufferSizeTracker.setBufferSize(GLBufferSizeTracker.java:118)
I am aware of not both of threads use the graphic resources simultaneously.
I have found that the problem causes with Meshes. Initializing a Mesh in initializer thread and rendering in main thread causes this error. But I don't know how to solve it.
Do you have any ideas to solve this problem?

As suggested in the comments, the AssetManager is the way to load most libGDX resources (audio, textures, etc) asynchronously while showing a splash or loading screen.
For other operations, running them in a background thread (or using one of the other Android or Java background task execution facilities) should be sufficient. To invoke libGDX routines like setScreen or others that need to be executed on the libGDX render thread, use Gdx.app.postRunnable, like this:
Gdx.app.postRunnable(new Runnable() {
#Override
public void run() {
// Do something on the main thread
myGame.setScreen(postSplashGameScreen);
}
});
Depending on the visibility of myGame and postSplashGameScreen it may be easier to construct the Runnable in a different context and then pass it over to the background thread to post when its done.

My workouround is using Actions in my loading screen method:
#Override
public void show() {
stage.addAction(Actions.sequence(Actions.delay(0.5f), action_loading_assets_and_other_stuff, Actions.delay(0.5f), action_setScreen));
}
Actions.delay(0.5f) makes the magic - game not freezing

The action delay did it for me, too. I just sequence a delayaction with 0.2f and a runnable action on the stage in the loading screens show() method. Now the loading screens render method is called a few time while while the 0.2 sec delay which draws the screen and i can proceed stuff in the runnable action.

my line of code is not executing in delay - android

The strangest thing is happening. In my onClick(View ...) I have blocks of code, mostly 'if/else' blocks. The sequence is (in pseudo-code, to save you lengthy code):
I have an image that needs setting using imageButton.setImageResource(randomImage); then
I have a MediaPlayer associated with this image that needs playing, then
I place a sleep(1800) here otherwise the MediaPlayer runs into the next MediaPlayer (this works fine)
This image is compare to another image. If its not the same, then another MediaPlayer named 'boo' is played, and the image that should have been displayed in code 1. above, is replaced by 'flag' image. else //if its the right image then
Switch to 'another' image, play it's corresponding MeidaPlayer, Play a 'cheers' MediaPlayer and change image to a 'tick' image, then do some other logic stuff.
But what is happening is that the code 2. is playing, code 3. is happening. code 4. only the 'boo' mediaplayer is happening and I notice the imagebutton flashing. The image that was supposed to be set in code 1. is delayed and is happening only AFTER the 'boo' mediaplayer. The 'flag' image that replaces the first image setting in code 1. is happening but because code 1. is in delay, what is happening is that the image is not changing (although it is, it's just in delay and then it flashes so quickly that it appears not to change). So code 1. is in delay.
Also, if it goes into the else and the right image is clicked, then the image in code 5. DOES switch to 'another', but the corresponding MeidaPlayer doesn't play, the 'cheers' MediaPlayer doesn't play, the 'tick' image doesn't display, and the other logic doesn't occur. Its as if it is ignoring the code.
What's happening here? Is this a multi-threading situation here? Grouping different parts of the code in their own threads and starting them at once only throws exceptions. Any help will be greatly appreciated!

If you want to delay your code, use Handler.postDelayed(Runnable, long). This won't block the UI thread, and will execute when you want it to.
Whitout your code, it's really unclear what are you trying to achive, and how are you trying to achieve it.

Just to explain Adam's idea.
Put this in your Activity class :
final Handler handler = new Handler();
Runnable _rnbl = new Runnable() {
public void run() {
// Your code
}
};
And call it like this
handler.postDelayed(_rnbl , 5000);

Graphics Choppy

I was trying to make an into transition to my game by having two bitmaps slide apart, like a garage door opening from the middle and half sliding downwards and half upwards. Anyway, when I do it, it looks really choppy and the frame rate seems unstable/unreliable. Here's how I'm doing it.
public class TFView extends View{
...
public void startlevel(Canvas c){
long l =(SystemClock.currentThreadTimeMillis()-starttime)/3;//*(height/500);
if(l<1000){
c.drawBitmap(metalbottom,0,height/2+l,p);
c.drawBitmap(metaltop,0,0-l,p);}
}
public void endlevel(Canvas c){
long l =(SystemClock.currentThreadTimeMillis()-failtime)/3;
if(l>=height/2){
c.drawBitmap(metaltop, 0, 0, p);
c.drawBitmap(metalbottom, 0,height/2 , p);
}
else{
c.drawBitmap(metalbottom,0,-height/2+l,p);
c.drawBitmap(metaltop,0,height-l,p);}
}}
and i set the times for when I want to open/close the doors respectively. So what do you think I should change to make it a more smooth transition? Would converting it to surfaceview help?

I had the same problem. I know what you mean with "choppy". The animation speed is NOT consistent even though you have a time based animation i.e. you are using
SystemClock.currentThreadTimeMillis()
The choppiness is caused by currentThreadTimeMillis(). It "returns milliseconds running in the current thread". That is, when you use currentThreadTimeMillis() "time" only elapses when the current thread is RUNNING. But your renderer thread is NOT ALWAYS running - as you would expect in a multitasking environment. Thus every time the thread is not running your animation is also not "running" (time is not elapsing).
Solution: Use
SystemClock.elapsedRealtime()

I have to admit I'm not the best when it comes to animation in Android but I thought I'd contribute.
From your explanation, could you use TranslateAnimation? Your animation would then be very smooth.
As far as I'm aware, if the animations Android provides are not sufficient you should be drawing your graphics in a separate thread, implementing SurfaceView.
This may help or take a look at the Lunar Lander example.

How to use AnimationDrawable in getView with Gallery

I'm creating a gallery view where I'm loading images from the web. While the images are loading, I want to display an animation as a placeholder for each image. I figured this could be done using an AnimationDrawable, however, the animation won't start. The first frame of the animation loads as expected, and if I use the same in for example onWindowFoucsChanged in an activity, everything works fine.
Inside the getView method of my GalleryItemCursorAdapter (which extends SimpleCursorAdapter) I'have the following snippet:
AnimationDrawable frameAnimation = (AnimationDrawable) mContext.getResources().getDrawable(R.drawable.loading);
holder.picture.setImageDrawable(frameAnimation);
frameAnimation.setCallback(holder.picture);
frameAnimation.setVisible(true, true);
frameAnimation.start();
holder.picture is an ImageView. I get no errors, and (very) similar code seems to work fine other places, leading me to believe this may be related to similar to the onCreate issues for animations reported elsewhere. I've tried some variations of the above code, too.
My questions:
Is there an easier/better way to display a loading animation?
What can I do to make the above example work (if at all possible)?

create a new thread and start ..
new Thread(new Runnable() {
public void run(){
// some code that runs outside the ui thread.
frameAnimation.start();
}
}).start();