Can I suggest you to look at the source code of this game? http://code.google.com/p/replicaisland/
It's a great little 2d side scroller with well structured and optimized code -- a lot to be learned from it. I am in no way affilitaed with that project, just came across it. On Apr 24, 7:21 am, Jon mailinglists <[email protected]> wrote: > Hi all, > > Like everyone else I'm doing a game to learn a bit about the android > platform. I've now reached a point where I need to optimize my draw > function and I'm trying to figure out the pros and cons of different > paths to take. I'm pretty new to graphics (but not programming) so my > questions might seems stupid, and my native language isn't English but > please bear with me. I'll be trying to explain as well as I can and > hopefully giving a bite more info than needed rather than less. > > It's "simple" 2D graphics we're talking about here. Doing frame > animations from a sprite sheet with sequences of movement for > different creatures, so basically I'm painting a portion of the sprite > sheet to the canvas, a little moved each time to make it look it's > walking/driving/running. The "game plan" is larger than the screen so > there's a view port Rectangle I use to draw what's on screen. I'm > doing this threaded pretty much like the lunar lander example. My > current draw function does: > > 1. Update physics, set boolean to updated if anything happened > 2. Draw global BitMap object containing last frame on the canvas if > nothing has happened, otherwise: > 3. Draw the part of the background currently visible, this draws over > everything old > 4. Loop through my objects, if any part of them is inside the view > port draw them and let the canvas sort out what's needed and what's > not > 5. Store draw the update on the "static" background > > Something like this: > private Bitmap bg = ... the large background image > private Bitmap sprites = ... the animations > private Bitmap screenBM = .. the "static" image > private Canvas screenC = new Canvas (screenBM); > private boolean noUp = false; > private MyClass creatures = new MyClass[10]; > > �...@override > public void run() { > Canvas c; > while (_run) { > c = null; > try > { > c = mSurfaceHolder.lockCanvas(null); > synchronized (mSurfaceHolder) { > updatePhysics (SystemClock.uptimeMillis (), c); > > if (noUp) > c.drawBitmap(cp, 0, 0, null); // redraw the > old > else > draw (c); > } > } > finally > { > if (c != null) > mSurfaceHolder.unlockCanvasAndPost(c); > } > } > > } > > public void draw (Canvas c) > { > screenC.drawBitmap (bgImage, viewPort, mapScreen, null); > Rect trans = new Rect (); // used to transform to the current > view port > for (int i = 0; i < creatures.length; i++) > { > if (creatures[i] != null && !creatures[i].dead) > { > trans.left = creatures[i].pos.left - > viewPort.left; > trans.right = creatures[i].pos.right - > viewPort.left; > trans.top = creatures[i].pos.top - > viewPort.top; > trans.bottom = creatures[i].pos.bottom - > viewPort.top; > if ( trans.left < mapScreen.right && > trans.right > mapScreen.left && > trans.top < mapScreen.bottom && > trans.bottom > mapScreen.top) > { > > screenC.drawBitmap(creatureAnimBitmap, frameCoords, trans, null); > } > } > } > co.drawBitmap(screenBM, 0, 0, null); > } > > I'm sure this isn't a very effective method for handling this, > especially not when the game physics is demanding and one wants a nice > frame rate. What would be the more effective way to do this? I've > tried figuring out how "clipRect (float left, float top, float > right, float bottom, Region.Op op)" works but I haven't been very > successful at that, not many examples out there explaining what it > does exactly. > > My guess would be that I should keep track of all movement of my > objects and have an int/float based array (to avoid the dreaded GC) > with a rectangle covering the previous position and the current and > just redraw that part. > > Or am I looking in the wrong direction? Is > Canvas.save/translate/restore the way to go if I want it to be > efficient? Or is it something completely different I should do? > > To sum up my rambling: > 1. I understand Rects are inefficient and expensive, is that so? > 2. What is the best way to handle things that would completely or > partially be drawn outside the view port? > 3. Is clipping, translate or just drawing pos based most efficient? > > 4. And since you've read through all this a little bonus question: Do > people tend to have two threads, one for synchronized drawing and only > doing that and one for physics or is one large thread doing both the > way to go? > > Sorry for the bandwidth, the only thing missing is a 5 MB word > document with an animated GIF in it, and thanks in advance > > Jon > > -- > You received this message because you are subscribed to the Google > Groups "Android Developers" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group > athttp://groups.google.com/group/android-developers?hl=en -- You received this message because you are subscribed to the Google Groups "Android Developers" group. 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