Spring Force

[nshelton]

https://github.com/mxsage/growth/blob/master/src/simulation.cpp#L390

hey, I'm working on a compute shader version of this. I noticed that this is a little different from the spring force described in the lomas paper, which would be more like

{
    glm::vec3 target;
    for (auto l : p.links)
    {
        glm::vec3 d =  p.position - cells[l].position;
        d = glm::normalize(d);
        target += cells[l].position + parameters.springLength * d;
    }

    target /= p.links.size();
    target -= p.position;
    p.delta += target * parameters.springFactor;
}

target doesn't subtract p.position at the end, so it shouldn't be used as a delta. Also the sum equation is a little different, yours may be equivalent, not sure. But the delta thing is definitely a problem