On 08/12/09 16:33, Yves Moisan wrote: > So from adbea to (acba + adebca) > > I know the distances from both a and b and I need to draw segments bc > and ac, so I need to find the intesection of the two circles centered at > a and b with the known radii I have. Is there a function that would > return the two intersection points of the circles and preferably only > the one contained in my polygon ?
I don't think there is such a function but I see at least two other solutions: 1 - Approximate the circle by constructing a linestring with many of segments (I use 50 to 200 segments for the whole cirlce depending on the precesion I need). Using ST_Intersect and ST_Within will let you determine C quite easily. 2 - Use some trigonometry to determine c by other means (like working with the two right-angled triangles contained in acb). -- Maxime _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
