Spheres Spheres everywhere

[Apollo_Ares]

Okay, This is probably stupid (I should know how to do it) but I have a scripit generate a three dimensional location (it generates x, y, and z values). I need to check with my MySQL database to make sure that this new set (x,y,z) is atleast 20 units in radius away form the nearest one. So given $location_x, $location_y, and $location_z how would I create an array of loactions 20 units away and check it with previous stored $location_x, $location_y, and $location_z values?

[Sxooter]

Hey, why not use a database that already has geometric types:

http://www.postgresql.org/docs/7.4/static/datatype-geometric.html

and geometric functions:

http://www.postgresql.org/docs/7.4/static/functions-geometry.html

[crimaniak]

while you have only old MySQL you can select cube (using indexes -> fast) and then select points inside

$delta=20;
// sorry, I like objects
$point->x=$location_x;
$point->y=$location_y;
$point->z=$location_z;

"SELECT * FROM point

WHERE
x>".($point->x-$delta)." AND x<".($point->x+$delta)." AND "
y>".($point->y-$delta)." AND y<".($point->y+$delta)." AND "
z>".($point->z-$delta)." AND z<".($point->z+$delta)." AND
SQRT(POV(x-$point->x,2)+POV(y-$point->y,2)+POV(z-$point->z,2)) < $delta"

[Apollo_Ares]

I'll look into that database, thanks🙂

Using my old MySQL I have already figured out how to select a cube. This is how I was about to do it:

Given newly generated $location_x, $location_y, and $location_z values:

$near_x = range (($location_x - 20), ($location_x + 20));
$near_y = range (($location_y - 20), ($location_y + 20));
$near_z = range (($location_z - 20), ($location_z + 20));

Then I query the database to find values in which they have the near arrays in common. I am not sure which is more efficient, yours or mine, but the major problem is I want a sphere not a cube.

[Apollo_Ares]

lol, I jsut found out that my server provided already has Postgresql. It was just waiting there for me to use.🙂 Don't know how to, but it is there. Some where... lol