Mushroom growing system

[timur04]

I created a particle system that grows mushrooms but I'm struggling with 2 issues:

1. The caps follow the growing path, but spin in an unwanted way and flip at the end. ( particle orientation )

2. What can be done to prevent them from interesting each other. I want to grow thousands of them and can see this as a big issue. 
I know I can increase the ground surface and have spawn less, but is there a way to have them super dense and minimize intersections? 

Thanks!

mushroom_system_v001.hip

[eimk]

1. The orient attribute is driven by velocity, which becomes very shaky towards the end. This is because of the wind force. Here's a visualisation of velocity (sorry for the bad quality gif):

 

If you reduce the effect of the wind force as the particles slow down then velocity will be more stable:

I used a VEXpression on the wind node to reduce the amplitude over time but you could achieve the same effect in multiple ways.

2. You could try POP Steer Avoid or other crowd dynamics nodes. And/or scatter points on the source geometry before the DOP network, set their @pscale and use a point relax. Then the points will be spaced enough before the sim starts.

[timur04]

Oh wow, thanks for your advice. Do you have the VEX expression handy?

[timur04]

The problem I'm having is they keep spinning even if they point in the right direction. 

[timur04]

Basically I need a VEX expression that would slow down and stop p@orient change over @age.

[eimk]

The VEXpression I used on the pop wind node was:

amp *= 1 - clamp(@age/3, 0, 1);

Dividing by 3 because they all seem to stop before their age reaches 3 seconds.

I didn't notice them spinning before, sorry. If you wire the align node right into the matrix to quaternion the rotation will stop, although I'm not familiar enough with matrix maths to know why.

Here's the scene file:

mushroom_system_OD.hipnc

[timur04]

Wooohoo! thanks so much!