下面的函数创建了一个由4个点组成的多边形正方形,我假设最后5个点关闭了正方形,我需要它至少有24个点并组成一个圆。有什么想法吗?

function getRadius($point="POINT(-29.8368 30.9096)", $radius=2)

{

$km = 0.009;

$center = "GeomFromText('$point')";

$radius = $radius*$km;

$bbox = "CONCAT('POLYGON((',

X($center) - $radius, ' ', Y($center) - $radius, ',',

X($center) + $radius, ' ', Y($center) - $radius, ',',

X($center) + $radius, ' ', Y($center) + $radius, ',',

X($center) - $radius, ' ', Y($center) + $radius, ',',

X($center) - $radius, ' ', Y($center) - $radius, '

))')";

$query = $this->db->query("

SELECT id, AsText(latLng) AS latLng, (SQRT(POW( ABS( X(latLng) - X({$center})), 2) + POW( ABS(Y(latLng) - Y({$center})), 2 )))/0.009 AS distance

FROM crime_listing

WHERE Intersects( latLng, GeomFromText($bbox) )

AND SQRT(POW( ABS( X(latLng) - X({$center})), 2) + POW( ABS(Y(latLng) - Y({$center})), 2 )) < $radius

ORDER BY distance

");

if($query->num_rows()>0){

return($query->result());

}else{

return false;

}

}

在js版本下面,这个工作非常完美

var findCirclePolygons = function(point, r)

{

var d2r = Math.PI / 180;

this.circleLatLngs = new Array();

numPoints = 24;

var circleLat = r * 0.009; // Convert degrees into km

var circleLng = circleLat / Math.cos(point.lat() * d2r);

for (var i = 0; i < numPoints + 1; i++) {

var theta = Math.PI * (i / (numPoints / 2));

var vertexLat = point.lat() + (circleLat * Math.sin(theta));

var vertexLng = parseFloat(point.lng()) + parseFloat(( circleLng * Math.cos(theta)));

var vertextLatLng = new google.maps.LatLng(vertexLat, vertexLng);

this.circleLatLngs.push(vertextLatLng);

}

// Set options

var options = {

paths: circleLatLngs,

strokeColor: "#0055ff",

strokeOpacity: 1,

strokeWeight: 1,

fillColor: "#0055ff",

fillOpacity: 0.35

};

// Return

return options;

};