The program is pretty simple right now. I have a triangle that I want to bounce around the screen. I have a moveTo(x,y) function in the triangle class. The triangle moves if the function is called on the Renderer thread but the screen is blank if I try to use the function on another thread. This is the first time I've dealt with threading, I'll be honest. I figure I need to use a Lock but I don't really know how to go about doing it...

When I comment out running the game thread from the activity, the triangle is drawn and even moves around as I touch the screen as input is received on the rederer's thread. When I let it run, I get a black screen.

public class GLView extends GLSurfaceView {
private StateManager _manager;
private GLRenderer _renderer;

public GLView(Context context, StateManager m) {
super(context);
_manager = m;
_renderer = new GLRenderer(_manager);
setRenderer(_renderer);
}

public boolean onTouchEvent(final MotionEvent event){
queueEvent(new Runnable() {
public void run() {
_manager.Input(event.getX(), event.getY());
}
});

return true;
}

}

public class GLRenderer implements GLSurfaceView.Renderer {
private StateManager _manager;

public GLRenderer(StateManager m){
_manager = m;
}

public void onDrawFrame(GL10 gl) {
gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
_manager.Draw(gl);
}

public void onSurfaceChanged(GL10 gl, int width, int height) {
gl.glViewport(0, 0, width, height);

gl.glMatrixMode(GL10.GL_PROJECTION);
gl.glLoadIdentity();
GLU.gluOrtho2D(gl, 0, width, height, 0);

gl.glMatrixMode(GL10.GL_MODELVIEW);
gl.glLoadIdentity();
}

public void onSurfaceCreated(GL10 gl, EGLConfig config) {
gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_FASTEST);

gl.glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
gl.glShadeModel(GL10.GL_FLAT);

gl.glDisable(GL10.GL_DEPTH_BUFFER_BIT);
gl.glDisable(GL10.GL_DEPTH_TEST);
gl.glDisable(GL10.GL_CULL_FACE);
gl.glDisable(GL10.GL_DITHER);
gl.glDisable(GL10.GL_LIGHTING);

//gl.glEnable(GL10.GL_TEXTURE_2D);

//gl.glTexEnvx(GL10.GL_TEXTURE_ENV, GL10.GL_TEXTURE_ENV_MODE, GL10.GL_MODULATE);
}

}



public class GameThread implements Runnable {
private StateManager _manager;
private GLView glV;

private boolean paused = false;


public GameThread(State firstState){
_manager = new StateManager(firstState);
}

public void setView(Activity main){
glV = new GLView(main, _manager);
main.setContentView(glV);
}

public void pause(){paused = true; glV.onPause();}
public void resume(){paused = false; glV.onResume();};

public void run() {
while(_manager.IsRunning()){
if(!paused){
_manager.Update();
}
}

}

}



(I'm aware that dx doesn't change, I made it static in case the screen was just blank because the triangle moved off the screen before being drawn)
public final class TestGL extends State {
private Triangle triangle;

private float dx, dy;

public TestGL(){
triangle = new Triangle();

dx = 100;
dy = 0;
}

@Override
public void Input(float x, float y) {
triangle.moveTo(x, y);
}

@Override
public void Update() {
triangle.moveTo(dx, dy);
}

@Override
public void Draw(GL10 gl) {
triangle.draw(gl);
}

}

Hmm. I'm a little closer... I added a ReentrantLock to the statemanager. Then in the update method I try to lock the state manager before updating it. Same for on the Renderer thread. Now the triangle flickers occasionally onto the screen. lol

I assume the problem is that the draw thread isn't guaranteed a lock. How do I guarantee it a lock?

I tried looping in the draw thread until it locks... this... works but it's not smooth. I'd like the draw thread to be guaranteed a lock when it wants it. Anyone know how I'd go about this?