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    <p>MySQL can't check a point in poly yet. It will check if your point is within the ([minX, maxX], [minY, maxY]). Also, I don't see <code>within</code> in MySQL documentation.</p> <blockquote> <p>Note</p> <p>Currently, MySQL does not implement these functions according to the specification. Those that are implemented return the same result as the corresponding MBR-based functions. This includes functions in the following list other than Distance() and Related(). </p> <p>These functions may be implemented in future releases with full support for spatial analysis, not just MBR-based support.</p> </blockquote> <p><a href="http://dev.mysql.com/doc/refman/5.4/en/functions-that-test-spatial-relationships-between-geometries.html" rel="nofollow noreferrer">From here</a></p> <p>I used a <a href="http://alienryderflex.com/polygon/" rel="nofollow noreferrer">point-in-poly ray-tracing</a> algorithm, which can be quite accurate outside of polar regions if the lines aren't long. Otherwise you'll need to solve spherical triangles.</p> <p>The simple implementation is like this:</p> <pre><code>create table point (x int, y int...) /* int values (int(lat * 10^6)) for better performance */ create table poly (x1 int, y1 int, x2 int, y2 int...) /* temporary table for 1 poly only */ </code></pre> <p>query that selects points inside the poly:</p> <pre><code>select point_id from point, poly where ((y&lt;y2 and y&gt;=y1) or (y&lt;y1 and y&gt;=y2)) and ((x&lt;x2 and x&gt;=x1) or (x&lt;x1 and x&gt;=x2)) group by point_id having sum(x1*(y2-y1)*sign(y2-y1) &lt; x*(y2-y1)*sign(y2-y1) - (y-y1)*(x2-x1)) % 2 </code></pre> <p>Counts 20,000 points vs a poly of 40 lines in 0.06 seconds on Pentium with 2.5Ghz. :)</p>
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    1. COIs there any php algorithm that can use geometric mysql data and check if a point is within given polyline?
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    2. COYou can extend the algorithm I've given for multiple polys. It's better to hand this job over to MySQL than to calculate it in PHP, but anyway you can see the article I've linked and re-write that piece of code in PHP.
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