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POCocos2d/Box2d game not running well on iPad Air
 

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  1. POCocos2d/Box2d game not running well on iPad Air
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    <p>I was about 95% done with my first cocos2d 2 / Box2d game when the iPad air was released. The game was running perfectly smoothly on an iPad mini, but on the Air it does not run smoothly at all - lots of stuttering and jerky movement, but with a frame rate of 60!</p> <p>I use a fixed time step, and after lengthy investigation, I found that by increasing the value of MAX_CYCLES_PER_FRAME from 2 to 3 the Air would run smoothly, but the mini then runs badly.</p> <p>So my question is, has anyone run into this and how might this be solved? I guess I could try to determine the H/W and change the value, but there must be a good reason for the disruption and a better way to accommodate all devices.</p> <p>Thanks TinoK</p> <p>Adding code snippet...</p> <pre><code>- (void) update:(ccTime) dt { static double UPDATE_INTERVAL = 1.0f/60.0f; static double MAX_CYCLES_PER_FRAME = 2; // 3 or more makes iPad air happy and iPad mini unhappy static double timeAccumulator = 0; timeAccumulator += dt; if (timeAccumulator &gt; (MAX_CYCLES_PER_FRAME * UPDATE_INTERVAL)) { timeAccumulator = UPDATE_INTERVAL; } // Advance score multiplier timeout if (_scoreMultiplierTimeout &gt; 0.0) { _scoreMultiplierTimeout -= dt; if (_scoreMultiplierTimeout &lt;= 0.0) { _scoreMultiplierTimeout = 0.0; _scoreMultiplier = 1; } } //int32 velocityIterations = 8; //int32 positionIterations = 1; int32 velocityIterations = 3; int32 positionIterations = 2; while (timeAccumulator &gt;= UPDATE_INTERVAL) { timeAccumulator -= UPDATE_INTERVAL; _world-&gt;Step(UPDATE_INTERVAL, velocityIterations, positionIterations); _world-&gt;ClearForces(); // Iterate over the bodies in the physics world for (b2Body* b = _world-&gt;GetBodyList(); b; b = b-&gt;GetNext()) { if (b-&gt;GetUserData() != NULL) { ... </code></pre>
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    1. COpost the code that shows how you update the physics world
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    2. COCode added. Incidentally, changes to velocityIterations and positionIterations was part of my trial & error investigation - It made no difference. Also note, iPhone 5 is also happy with MAX_CYCLES_PER_FRAME = 2 and unhappy with a value of 3.
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      1. POCocos2d/Box2d game not running well on iPad Air
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    3. COstepping multiple times per frame and at the same time incorporating delta time into updates makes no sense. Use a fixed time step, and step only once per frame. Increase iteration counts if you encounter simulation accuracy issues.
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      1. POCocos2d/Box2d game not running well on iPad Air
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