计算机与数学是息息相关的,计算机模型中无时无刻不体现数学的理念。例如余弦定理用来求两个文案的相似度。今天我这里解决的问题也与数学有关。实际需求是这样的,在项目当中,需要人工在百度地图中划分配送区域,要求划分出来的区域不能是杂乱无章的,即线段与线段之间不能相穿。当时接到这个需求有点懵逼,如何是好,开完会坐下来,慢慢画图发现划出的图形只要是凹凸多边形即可,突然茅塞顿开,问题迎刃而解,因为规则的凹凸多边形的顶点数与边数相等,根据这段理念简单写了一段验证,结果验证无误。
用对象的方式实现代码逻辑: <?php /** * 平面点 * * Class Point2D */ class Point2D { public $x; public $y; public function __construct($x, $y) { $this->x = $x; $this->y = $y; } public function __toString() { return "({$this->x}, {$this->y})"; } } /** * 平面线 * * Class Line2D */ class Line2D { /** * @var Point2D */ public $p1; /** * @var Point2D */ public $p2; public function __construct(Point2D $p1, Point2D $p2) { $this->p1 = $p1; $this->p2 = $p2; } public function __toString() { return "({$this->p1}, {$this->p2})"; } } /** * 平面向量 * * Class Vector */ class Vector extends Line2D { /** * 向量 * * @var Point2D */ public $v; public function __construct(Point2D $p1, Point2D $p2) { parent::__construct($p1, $p2); $this->v = new Point2D($p2->x - $p1->x, $p2->y - $p1->y); } public function __toString() { return "({$this->p1}->{$this->p2})"; } /** * 向量叉积 * * @param Vector $v1 * @param Vector $v2 * @return Vector */ public static function mul(Vector $v1, Vector $v2) { return $v1->v->x * $v2->v->y - $v2->v->x * $v1->v->y; } } public function checkMapIsRegular($aPoint) { $aFormatPoint = array(); $aFormatLine = array(); try { if ($aPoint) { //拆分出坐标点,初始化坐标对象 foreach ($aPoint as $item) { list($pointX,$pointY) = explode(',' ,$item); $aFormatPoint[] = array('x' => $pointX, 'y' => $pointY); } //按顺序构成矢量线 $index = count($aFormatPoint) - 1; foreach ($aFormatPoint as $key=>$point) { $aFormatLine[]['start'] = $point; if ($index == $key) { $aFormatLine[$key]['end'] = $aFormatPoint[0]; } else { $aFormatLine[$key]['end'] = $aFormatPoint[$key+1]; } } $aOutPoint = $aFormatLine; $edgeCount = 0; $vertexCount = count($aOutPoint); array_shift($aFormatLine); //两两求交点 foreach ($aOutPoint as $key=>$aLine) { if (empty($aFormatLine)) { continue; } foreach ($aFormatLine as $innerKey => $aInnerLine) { //初始化坐标对象 $oAPointStart = new Point2D($aOutPoint[$key]['start']['x'],$aOutPoint[$key]['start']['y']); $oAPointEnd = new Point2D($aOutPoint[$key]['end']['x'],$aOutPoint[$key]['end']['y']); $oBPointStart = new Point2D($aFormatLine[$innerKey]['start']['x'],$aFormatLine[$innerKey]['start']['y']); $oBPointEnd = new Point2D($aFormatLine[$innerKey]['end']['x'],$aFormatLine[$innerKey]['end']['y']); //两两画出矢量线 $vector = new Vector($oAPointStart, $oAPointEnd); $vABStart = new Vector($oAPointStart, $oBPointStart); $vABEnd = new Vector($oAPointStart, $oBPointEnd); $isInterSect1 = false; $isInterSect2 = false; if (Vector::mul($vABStart, $vector) * Vector::mul($vABEnd, $vector) <= 0) { $isInterSect1 = true; } $oppositeVector = new Vector($oBPointStart, $oAPointStart); $oVABStart = new Vector($oBPointStart, $oAPointEnd); $oVABEnd = new Vector($oBPointStart, $oBPointEnd); if (Vector::mul($oppositeVector, $oVABEnd) * Vector::mul($oVABStart, $oVABEnd) <= 0) { $isInterSect2 = true; } if ($isInterSect1 && $isInterSect2) { $edgeCount += 1; } } array_shift($aFormatLine); } } if ($edgeCount == $vertexCount) { return true; } else { return false; } }catch (\Exception $e) { return $e->getMessage(); } }
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