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js判断一点是否在一个三角形内

<html> 
<head> 
<style> 
*{margin:0;padding:0;} 
</style> 
<img src="/_New/_cj/myeditor/sysimage/space.gif" class="ewebeditor__script" _ewebeditor_fake_tag="script" _ewebeditor_fake_value="%3Cscript%3E%20%0D%0Afunction%20a(x%2Cy%2Ccolor)%20%0D%0A%7Bdocument.write(%22%3Cimg%20border%3D'0'%20style%3D'position%3A%20absolute%3B%20left%3A%20%22%2Bx%2B%22%3B%20top%3A%20%22%2By%2B%22%3Bbackground-color%3A%20%22%2Bcolor%2B%22'%20src%3D'px.gif'%20width%3D1%20height%3D1%3E%22)%7D%20%0D%0A%3C%2Fscript%3E"> 
</head> 
<body onmouseup = 'alert(rule(event.clientX,event.clientY));'> 
<img src="/_New/_cj/myeditor/sysimage/space.gif" class="ewebeditor__script" _ewebeditor_fake_tag="script" _ewebeditor_fake_value="%3Cscript%3E%20%0D%0Afunction%20line(x1%2Cy1%2Cx2%2Cy2%2Ccolor)%20%0D%0A%7B%20%0D%0Avar%20tmp%3B%20%0D%0Aif(x1%3E%3Dx2)%20%0D%0A%7B%20%0D%0A%20%20tmp%3Dx1%3B%20%0D%0A%20%20x1%3Dx2%3B%20%0D%0A%20%20x2%3Dtmp%3B%20%0D%0A%20%20tmp%3Dy1%3B%20%0D%0A%20%20y1%3Dy2%3B%20%0D%0A%20%20y2%3Dtmp%3B%20%0D%0A%7D%20%0D%0Afor(var%20i%3Dx1%3Bi%3C%3Dx2%3Bi%2B%2B)%20%0D%0A%7B%20%0D%0A%20%20x%20%3D%20i%3B%20%0D%0A%20%20y%20%3D%20(y2%20-%20y1)%20%2F%20(x2%20-%20x1)%20*%20(x%20-%20x1)%20%2B%20y1%3B%20%0D%0A%20%20a(x%2Cy%2Ccolor)%3B%20%0D%0A%7D%20%0D%0A%7D%20%0D%0Afunction%20rule(x%2Cy)%20%0D%0A%7B%20%0D%0Ax%20%3D%20x%3B%20%0D%0Ay%20%3D%20y%3B%20%0D%0Ar1%20%3D%20y%20-%20100%20-%20(300-100)%2F(500-400)*(x-400)%3B%20%0D%0Ar2%20%3D%20y%20-%20300%3B%20%0D%0Ar3%20%3D%20y%20-%20300%20-%20(100-300)%2F(400-300)*(x-300)%3B%20%0D%0Aif%20(r1%3E0%26%26r2%3C0%26%26r3%3E0)%20%0D%0A%7B%20%0D%0A%20%20return%20%22%E5%9C%A8%E4%B8%89%E8%A7%92%E5%BD%A2%E5%86%85%EF%BC%81%22%3B%20%0D%0A%7D%20%0D%0Aelse%20%0D%0A%7Breturn%20%22%E4%B8%8D%E5%9C%A8%E4%B8%89%E8%A7%92%E5%BD%A2%E5%86%85%EF%BC%81%22%3B%7D%20%0D%0A%7D%20%0D%0Aline(400%2C100%2C500%2C300%2C%22ff0000%22)%3B%20%0D%0Aline(500%2C300%2C300%2C300%2C%22ff0000%22)%3B%20%0D%0Aline(300%2C300%2C400%2C100%2C%22ff0000%22)%3B%20%0D%0A%3C%2Fscript%3E"> 
</body> 
</html>

　　 [Ctrl+A 全选注:如需引入外部Js需刷新才能执行]

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