javascript - There are many plots saved in the database. The area of ​​each plot is determined by the longitude and latitude of four vertices. If the longitude and latitude of a point are known, how to determine which plot the location belongs to?

Please give me an idea~

Reply content:

Please give me an idea~

Correct the demand, the po owner’s demand is [geofencing]

Solution:
PostGis+PostGreSQL
ElasticSearch/Solr

It’s probably not possible to rely solely on MySQL.
Or redesign the library

place_id	name
1	Block 1

id	place_id	lat	lng
1	1	1.1111	1.1111
2	1	1.1111	1.1111
3	1	1.1111	1.1111
4	1	1.1111	1.1111

Reference materials: http://www.cnblogs.com/LBSer/...

This seems to be a purely mathematical problem. As for the idea, you can use four small triangles T1-T4 to complete the quadrilateral into a rectangle R. It is not convenient to draw a picture now, so you can imagine it yourself. Then judge and give the point p

<code>p 在 R 内   &&   p 不在 {T1-T4} 内</code>

Define a point object: P[x,y], x is the latitude, y is the longitude
The four vertices of the area of ​​​​the plot are: A[x,y], B[x,y], C[x,y] , D[x,y]
The known point is: ptr[x,y]

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Uh~~
You should give me a few samples~
Otherwise, it would be too wordy to teach you about geography~

Use mysql spatial functions and operations. When saving, just save a polygon area directly. Use ST_Contains function when making judgment

Use POINT, ST_AsText, POLYGON, ST_X, ST_Y, ST_DISTANCE, these are much better than directly saving longitude and latitude.

http://dev.mysql.com/doc/refm...