Weight penalty (draft)

effective speed = base speed * penalty

x = current load / maximal load

weight1 is a relative load where penalty starts

weight2 is a relative load where penalty is at its maximum (cannot move anymore)

penalty(x) = 1.0 for x < weight1

penalty(x) = 1.0 - ((x-weight1)/(weight2-weight1))^{2 for x >= weight1 and x < weight2}

penalty(x) = 0.0 for x >= weight2

Example for weight1=0.6 and weight2=1.3