I think i need a quadtree but not sure how to make it

I am generating a forest.
I want next generated tree has distance X of all allready generated trees.
I am using vec_dist to generate map but is slow (500) trees
I don´t know if i should make my function calculating distance on 2d for speed up?
Or create a grid over map and only make collisition testing inside the cell?
Or maybe both?
I have the source of octree made on c++ , could be usefull translate to lite-c or the effort don´t pays and is faster to make from sctach?

Any advice or link are welcome.
Thanks in advance

Hi!

I saw some code in the Lite-c contributions done by Alan
This might be what your looking for.

Use the search and write tcmain.c

The algorithm of vec_dist is the following:

That means it is really fast. There must be something different that slows your code/ game down, the fact that you create 500 entities at once should be the problem.
Immediately after creation set their passable flag, this will be much faster:

you = ent_create(tree...)
set(you,PASSABLE);

vec_dist is slow because it uses sqrt, especially when you have to use it many times per frame. If you want better speed, you could use the squared length (i.e. the same function as vec_dist but without the sqrt) to compare distances, although at the cost of accuracy on longer distances.

Thank you all for your help.