func (c *Contact) calculateDesiredDeltaVelocity(duration m.Real) {
const velocityLimit m.Real = 0.25
var velocityFromAcc m.Real
// calculate the acceleration induced velocity accumlated this frame
var tempVelocity m.Vector3
if c.Bodies[0].IsAwake {
tempVelocity = c.Bodies[0].GetLastFrameAccelleration()
tempVelocity.MulWith(duration)
velocityFromAcc += tempVelocity.Dot(&c.ContactNormal)
}
if c.Bodies[1] != nil && c.Bodies[1].IsAwake {
tempVelocity = c.Bodies[1].GetLastFrameAccelleration()
tempVelocity.MulWith(duration)
velocityFromAcc -= tempVelocity.Dot(&c.ContactNormal)
}
// if the velocity is very slow, limit the restitution
restitution := c.Restitution
if m.RealAbs(c.contactVelocity[0]) < velocityLimit {
restitution = 0.0
}
// combine the bounce velocity with the removed acceleration velocity
c.desiredDeltaVelocity = -c.contactVelocity[0] - restitution*(c.contactVelocity[0]-velocityFromAcc)
}
