More particles as more area is painted I want to populate trees along a road with Particles using weight painting to control the density.
My problem is that the particle system needs to know the final particles count - logically, I proceed from start to finish so with every newly painted areas, the tree density will more and more decrease as this number spreads to bigger area. This means I have to adjust and estimate the count every while, which is frustrating.
So is there any option how to tell the particle system to produce maximum (based on a weight paint) of 5 instances on area of i.e. 10x10 meters so the number of instances / particles will grow progressively as I paint?
As I haven't found any solution so far and this fixed-count workflow limits my daily work a lot, I have refreshed my "so-so programming skills" and I ended up with creating a Blender (2.79) addon which does this job for me.

With the addon, you set the Density parameter and the Emmission Number is adjusted accordingly:



I have placed the addon to Github and would be very happy is someone can test it and report any bugs.
https://github.com/jendabek/blender-particles-density