Hi, this may sound ridiculuos but i want to know how can i insert a
polygon into database, if i only know the radius of the polygon.

Like i have a polygon, centered at the origin, with radius, say 5. Now
how can i insert it into mysql database? I hope we need to know the
vertices of it before inserting.

How can this be achieved.

On 2011-03-07 07:26, shashi kanth wrote:
No, you will need more information. If the polygon is regular you will
need the origin and the number of vertices. If it is not regular, I'm
not sure what radius is supposed to mean.

/Lennart


[...]

Yes, the polygon will be a regular one, with a point of origin, like
(10,10) and with a radius. Also the number of vertices or the number
of sides can be provided. In such a case, how can i go ahead

On 2011-03-07 09:45, shashi kanth wrote:
Oh I forgot, you will for example need an angle for one of the vertices.
Otherwise you will have many possible vertice collections. Given that
you can calculate the vertices, and store them as a polygon.

I'm not a gis-user so there may be a function that takes these kind of
arguments and creates a polygon for you, but my guess is that you will
have to do some math in the application, and create the polygon your self.


/Lennart

In article <ad785d6c-51e5-4365-b303-9b647c526da3 (AT) j9g2000prj (DOT) googlegroups.com>, shashi kanth <dskanth.99 (AT) gmail (DOT) com> wrote:
Knowing only the radius, and not the number of sides and their lengths?
Impossible.

Yes, of course you need to know the vertices.
First, determine how many sides there are...

In article <5882e7af-a65c-4433-9240-6f2b002c39d7 (AT) w9g2000prg (DOT) googlegroups.com>, shashi kanth <dskanth.99 (AT) gmail (DOT) com> wrote:
You still need to specify the position of one vertex, else you will have an
infinite number of possible rotations for the polygon. Calculating the
positions of the remaining vertices is a straightforward exercise in
trigonometry, which is off-topic for comp.databases.mysql.

Try posting in alt.algebra.help or in one of the geometry.* newsgroups.

Just to extend upon what Doug has mentioned; you would need to know the centre, the number of sides, and at least one vertex. The radius would not then be required.

Also, see etiquette regards cross-posting vs multi-posting.

Thanks for your replies... let me see how far i could solve it.

Assuming:
- It's a regular polygon.
- The center is at (0,0).
- The radius of a polygon is the distance from the center to a vertex
(as opposed to the distance from the center to the closest point on
a side).
- One of the vertices is at (0,r) relative to the center.

Then in polar coordinates, all of the vertexes are distance r from
the origin. For an N-sided regular polygon, the angles are at
k*360/N degrees, where k varies from 0 to N-1. If one of the
vertices is at an arbitrary angle theta, add this to the angle for
each of the vertices, then reduce modulo 360 degrees.

Now convert to rectangular coordinates. If the center is not at
(0,0), add the coordinates of the center to each of the vertices.

Thanks for the reply, but i am still confused with this... i have
posted my question here:
http://stackoverflow.com/questions/5...certain-radius