first init

htdocs/lib2/logic/gis.class.php

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+<?php
+/***************************************************************************
+ *  You can find the license in the docs directory
+ *
+ *  Unicode Reminder メモ
+ ***************************************************************************/
+
+class gis
+{
+	static function ptInLineRing($sGeometry, $sPoint)
+	{
+		// thanks to Roger Boily, Gis Consulant
+		// posted at http://dev.mysql.com/doc/refman/5.1/en/functions-that-test-spatial-relationships-between-geometries.html
+
+		$counter = 0;
+		// get rid of unnecessary stuff
+		$sGeometry = str_replace("LINESTRING", "", $sGeometry);
+		$sGeometry = str_replace("(", "", $sGeometry);
+		$sGeometry = str_replace(")", "", $sGeometry);
+		$sPoint = str_replace("POINT", "", $sPoint);
+		$sPoint = str_replace("(", "", $sPoint);
+		$sPoint = str_replace(")", "", $sPoint);
+
+		// make an array of points of the polygon
+		$polygon = explode(",", $sGeometry);
+
+		// get the x and y coordinate of the point
+		$p = explode(" ", $sPoint);
+		$px = $p[0];
+		$py = $p[1];
+
+		// number of points in the polygon
+		$n = count($polygon);
+		$poly1 = $polygon[0];
+		for ($i=1; $i <= $n; $i++)
+		{
+			$poly1XY = explode(" ",$poly1);
+			$poly1x = $poly1XY[0];
+			$poly1y = $poly1XY[1];
+			$poly2 = $polygon[$i % $n];
+			$poly2XY = explode(" ",$poly2);
+			$poly2x = $poly2XY[0];
+			$poly2y = $poly2XY[1];
+
+			if ($py > min($poly1y,$poly2y))
+			{
+				if ($py <= max($poly1y,$poly2y))
+				{
+					if ($px <= max($poly1x,$poly2x))
+					{
+						if ($poly1y != $poly2y)
+						{
+							$xinters = ($py-$poly1y)*($poly2x-$poly1x)/($poly2y-$poly1y)+$poly1x;
+							if ($poly1x == $poly2x || $px <= $xinters)
+							{
+								$counter++;
+							}
+						}
+					}
+				}
+			} 
+			$poly1 = $poly2;
+		} // end of While each polygon
+		
+		if ($counter % 2 == 0)
+		{
+			return(false); // outside
+		}
+		else
+		{
+			return(true); // inside
+		}
+
+		return true;
+	}
+}
+?>