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  1. PO
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    <p>There are 2 things you should fix:</p> <ul> <li><p>Actually the <code>directionY</code> is (lets review your formula):</p> <pre><code>float directionY = pSceneTouchEvent.getY() - gun.getY(); </code></pre></li> <li><p>Your <code>directionX</code> and <code>directionY</code> are the shift elements of the touch position compare to your gun's <code>[top,left]</code> world position => so your <strong>calculated angle</strong> is actually the rotation around this gun's <code>[top,left]</code> position. Hence, thing should be:</p> <pre><code>gun.setRotationCenter(0, 0); </code></pre></li> </ul> <p>where (0,0) is the local [top, left] relative position to set the anchor for the rotation in the gun.</p> <p><strong>NOTE:</strong></p> <p>You should learn more about the Physics in AndEngine (Box2D). To do things as you want, normally, you should do as follows:</p> <ul> <li>Create a <strong><code>fix anchor body</code></strong> (may be a circle body) at where you want your <code>gun</code> to rotate around.</li> <li>Create a <strong><code>RevoluteJoint</code></strong> to pin your Gun with this anchor.</li> <li>Create and Dispose a <strong><code>Mouse Joint</code></strong> between your gun and a mouse point every time you <strong>Touch</strong> your gun and <strong>Release</strong> your touch.</li> </ul> <p>You can see the examples of AndEngine Examples in <code>Physics\Using a RevoluteJoint + MouseJoint</code>.</p> <p>This will help you create normal interactions as happened in the real world, regardless of calculating positions, rotations, or velocity of your body objects (cause physics engine will do them for you).</p> <p>And more, you can apply the same mechanism (by encapsulating the above procedure in functions or class) on any object within your game.</p>
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    1. COYour note only applies if the OP wants to make a game with physics, which may not be the case here.
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    2. COok John, because I saw the OP using AndEngine instead of native drawing surface, so I suggested here as for the consumable use of the engine. For the first look, I thought 'JustMe' was in the same of my case before when trying to put in much of Math then wasted much time to fix the runtime problems.
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    3. COSure, it's fine. I just wanted to make sure the OP won't use Box2D just to avoid doing a bit of math, as that would be a massive overkill and a performance/memory hog. Your answer is well written and makes sense.
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