else
blocking_force_ = (min_distance_ - distance_) / inverse_compress_strength_;
+ // If the spring is fixed, it's not clear what the natural value
+ // of blocking_force_ would be. -infinity_f works fine for now.
if (isnan (blocking_force_) || blocking_force_ == infinity_f)
- blocking_force_ = 0;
+ blocking_force_ = -infinity_f;
if (blocking_force_ >= 0)
inverse_compress_strength_ = 0;
distance_ = max (min_distance_, distance_ * r);
inverse_compress_strength_ = max (0.0, distance_ - min_distance_);
inverse_stretch_strength_ *= 0.8;
+ update_blocking_force ();
}
bool
programming_error ("insane spring constant");
else
inverse_stretch_strength_ = f;
+
+ update_blocking_force ();
}
void
{
inverse_compress_strength_ = (distance_ >= min_distance_) ? distance_ - min_distance_ : 0;
inverse_stretch_strength_ = distance_;
+ update_blocking_force ();
}
Real
Real force = max (f, blocking_force_);
Real inv_k = force < 0.0 ? inverse_compress_strength_ : inverse_stretch_strength_;
- if (isinf (force))
+ if (force == infinity_f)
{
programming_error ("cruelty to springs");
force = 0.0;
}
+ // There is a corner case here: if min_distance_ is larger than
+ // distance_ but the spring is fixed, then inv_k will be zero
+ // and we need to make sure that we return min_distance_.
return max (min_distance_, distance_ + force * inv_k);
}
+