javascript - 确定点是否在边界框内

Question

您将如何确定给定点是否在边界框内？

我的观点是 48.847172 ， 2.386597。

边界框：

    "48.7998602295",
    "48.8198640442",
    "2.46138595581",
    "2.48138619423"

Answer 1

像往常一样做：

if( bb.ix <= p.x && p.x <= bb.ax && bb.iy <= p.y && p.y <= bb.ay ) {
    // Point is in bounding box
}

bb是边界框，(ix,iy)是左上角坐标，(ax,ay)右下角坐标。 p是点(x,y)及其坐标。

Answer 2

此解决方案还考虑了 UI 发送一个跨经度 180/-180 的框的情况（在低缩放级别上映射视图，您可以看到整个世界，允许无限循环水平滚动，因此可能例如一个盒子的 bottomLeft.lng=170 而 topRight.lng=-170(=190) 并且包括 20 度的范围。

def inBoundingBox(bl/*bottom left*/: Coordinates, tr/*top right*/: Coordinates, p: Coordinates): Boolean = {
    // in case longitude 180 is inside the box
    val isLongInRange =
      if (tr.long < bl.long) {
        p.long >= bl.long || p.long <= tr.long
      } else
        p.long >= bl.long && p.long <= tr.long

    p.lat >= bl.lat  &&  p.lat <= tr.lat  &&  isLongInRange
}

Answer 3

如果您使用的是传单，您可以新建一个LatLngBounds并使用它的contains()操作：

var bounds = new L.LatLngBounds(
 new L.LatLng(gc.bbox['_northEast'].lat, gc.bbox['_northEast'].lng),
 new L.LatLng(gc.bbox['_southWest'].lat, gc.bbox['_southWest'].lng));

return bounds.contains(new L.LatLng(pos.latitude, pos.longitude))

Answer 4

这应该更快。

function doesPointCollide(p,box) {
    return !(p.x < box.left || p.x > box.right || p.y > box.bottom || p.y < box.top)
}

如果该点在任何维度之外，我们就知道它不在边界框中，否则它在边界框中，因此我们可以更快地忽略否定的情况。

Answer 5

这个答案与上面 kumetix 的答案相同；然而，就我的一生而言，我不明白那里发生了什么，因为它被浓缩了很多。这是带有详细解释的相同答案。另请注意，答案是在 Kotlin 中，而不是原始帖子所要求的 JavaScript，但它具有足够的可读性，因此转换为您的语言应该不会太糟糕。

首先定义 Coordinate2D 和 BoundingBox 类：

data class Coordinate2D (val latitude: Double, val longitude: Double)

data class BoundingBox (val north: Double, val east: Double, val south: Double, val west: Double)

这是确定一个点是否在任意边界框中的函数

fun isPointInBoundingBox(point: Coordinate2D, boundingBox: BoundingBox): Boolean {
    //given the bounding box is an imaginary rectangle in a coordinate system
    //bounding box has 4 sides - northLine, eastLine, southLine and westLine
    //initially assume the point is not in our bounding box of interest as such:
    var isPointEastOfWestLine = false
    var isPointWestOfEastLine = false
    var isPointSouthOfNorthLine = false
    var isPointNorthOfSouthLine = false

    if (boundingBox.east < boundingBox.west) {
        //if west coordinate has a bigger value than the east, 
        //the bounding box must be crossing the dateline
        //in other words, longitude 180 is inside the box
        //let's see what's happening with the point
        if (point.longitude >= boundingBox.west) {
            //imagine a bounding box where westernmost longitude is +170 and easternmost longitude is -170
            //if the point in question has a latitude of +171 as in the case expressed in the if
            //statement, then we can conclude that point lies east of the west line
            isPointEastOfWestLine = true

            //we can also infer that the point must lie west of east line because the point's longitude is positive
            //therefore, the point's position must be to the west of the easternmost longitude of the bounding box
            isPointWestOfEastLine = true
        }

        if (point.longitude <= boundingBox.east) {
            //imagine a bounding box where westernmost longitude is +170 and easternmost longitude is -170
            //if the point in question has a latitude of -171 as in the case expressed in the if
            //statement, then we can conclude that point lies west of the east line
            isPointWestOfEastLine = true

            //we can also infer that the point must lie east of the west line because the point's longitude is negative
            //therefore, the point's position must be to the east of the westernmost longitude of the bounding box
            isPointEastOfWestLine = true
        }
    } else {
        //in the else case, bounding box does not cross the dateline, so comparisons are more straightforward
        //longitudes range from -180 to +180; therefore, western side of a bounding box will always
        //have lower value than eastern side
        if (point.longitude >= boundingBox.west) {
            //in this case, point's longitude has a higher value than the west side of the bounding box
            //we can conclude that point lies to the east of the west line of the bounding box
            isPointEastOfWestLine = true
        }
        if (point.longitude <= boundingBox.east) {
            //in this case, point's longitude has a lower value than the east side of the bounding box
            //we can conclude that point lies to the east of the west line of the bounding box
            isPointWestOfEastLine = true
        }
    }

    //comparing latitudes are little bit easier. latitude values range from -90 to +90 where
    //-90 is the southern pole and +90 is the northern pole. The more north you go, higher the values.
    if (point.latitude >= boundingBox.south) {
        //point's latitude is higher, therefore, point must lie to the north of the south line
        isPointNorthOfSouthLine = true
    }

    if (point.latitude <= boundingBox.north) {
        //point's latitude is higher, therefore, point must lie to the north of the south line
        isPointSouthOfNorthLine = true
    }

    return isPointEastOfWestLine &&
            isPointWestOfEastLine &&
            isPointNorthOfSouthLine &&
            isPointSouthOfNorthLine
}

Answer 6

CGRect 和 CGPoint 有相当不错的实用方法（假设您不介意它们使用 CGFloat 来存储坐标 - 并且查看您的值，您不会:-)）。

你可以这样做：

// Create bounding box
CGRect area = CGRectMake(x, y, width, height);

// Define point
CGPoint point = CGPointMake(pX, pY);

/Check
BOOL isInside = CGRectContainsPoint(area, point);

Answer 7

将此函数用于 c plus plus 以检查点是否存在于矩形内

struct Box{

Vec2 corner1;
Vec2 corner2;
Vec2 corner3;
Vec2 corner4;

};

bool boxContainsPoint(Vec2 point, Box box){

//Calculate distances from corner to corner
float abL = box.corner1.getDistance(box.corner2);////////////////////
float bcL = box.corner2.getDistance(box.corner3);////////////////////
float cdL = box.corner3.getDistance(box.corner4);////////////////////
float daL = box.corner4.getDistance(box.corner1);////////////////////

//Calculate corner touch distance//////////////////////////////////
float apL = box.corner1.getDistance(point);/////////////////////////
float bpL = box.corner2.getDistance(point);/////////////////////////
float cpL = box.corner3.getDistance(point);/////////////////////////
float dpL = box.corner4.getDistance(point);/////////////////////////

//Here we calculate the touch area
//Heron's Formula
///////////////////////////////////////////////////////////////////
float area1 = (abL + apL + bpL) / 2;///////////////////////////////
float area2 = (bcL + bpL + cpL) / 2;///////////////////////////////
float area3 = (cdL + cpL + dpL) / 2;///////////////////////////////
float area4 = (daL + dpL + apL) / 2;///////////////////////////////
float a1 = sqrtf(area1 * (area1 - abL)*(area1 - apL)*(area1 - bpL));
float a2 = sqrtf(area2 * (area2 - bcL)*(area2 - bpL)*(area2 - cpL));
float a3 = sqrtf(area3 * (area3 - cdL)*(area3 - cpL)*(area3 - dpL));
float a4 = sqrtf(area4 * (area4 - daL)*(area4 - dpL)*(area4 - apL));

//Calculate the rectangle area
float A = roundf(abL*bcL);

//Check to see if the point contains the polygon rect
if(A ==roundf(a1 + a2 + a3 + a4)) return true;
return false;

}