Chipmunk引擎中碰撞行为可能在细微处与一般认识略有不同.
比如碰撞回调方法可能会重入.不知道方法(函数)重入概念的童鞋可以自行谷哥或度娘.
第一次碰撞方法还未返回,第二次碰撞回调又被调用了.至于它们是否运行在同一线程,这个不知道.至少我调试中都在一个线程里.但在一个线程里也会发生重入.这里研究的不深入,有错误请指出.
最开始碰撞回调方法如下:
<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">-(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">BOOL</span>)ccPhysicsCollisionBegin:(CCPhysicsCollisionPair *)pair star:(CCNode *)star stick:(CCNode *)stick{ StarType starType; <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (!star) { <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">YES</span>; } starType = ((Star*)star)<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">.starType</span>; star = <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">nil</span>; } <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//working</span> [star removeFromParentAndCleanup:<span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">YES</span>]; <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">YES</span>;}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li></ul>以上代码中的working短时间内偶尔会执行2次.第1次修改将star removeFromParentAndCleanup调用移至方法前部也不行.
第2次修改如下:
<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">@synchronized(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">self</span>){ <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (!star) { <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">YES</span>; } starType = ((Star*)star)<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">.starType</span>; [star removeFromParentAndCleanup:<span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">YES</span>]; star = <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">nil</span>; } <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//working...</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li></ul>任然不行,从日志上看star调用remove方法后其值仍有可能不为nil,导致if判断失败.
第3次修改增加了if判断条件为:
<code class="hljs php has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (!star || !star.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">parent</span>) { <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> YES;}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>代码逻辑工作正常,在第二次重入时,star.parent一定为(还是不能肯定,说”应该为”比较妥当 ;)nil,所以避免了再次调用working逻辑.
可能我代码逻辑也有问题,不能依赖于方法的重入次数.因为有了物理引擎回调这个不确定因素,所以使得问题发生的很显然.
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