Example #1
0
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)
}
Example #2
0
func transformToAxis(cube *CollisionCube, axis *m.Vector3) m.Real {
	cubeAxisX := cube.transform.GetAxis(0)
	cubeAxisY := cube.transform.GetAxis(1)
	cubeAxisZ := cube.transform.GetAxis(2)

	return cube.HalfSize[0]*m.RealAbs(axis.Dot(&cubeAxisX)) +
		cube.HalfSize[1]*m.RealAbs(axis.Dot(&cubeAxisY)) +
		cube.HalfSize[2]*m.RealAbs(axis.Dot(&cubeAxisZ))
}
Example #3
0
// penetrationOnAxis checks if the two boxes overlap along a given axis and
// returns the amount of overlap.
func penetrationOnAxis(one *CollisionCube, two *CollisionCube, axis *m.Vector3, toCenter *m.Vector3) m.Real {
	// project the half-size of one onto axis
	oneProject := transformToAxis(one, axis)
	twoProject := transformToAxis(two, axis)

	// Project this onto the axis
	distance := m.RealAbs(toCenter.Dot(axis))

	// Return the overlap (i.e. positive indicates
	// overlap, negative indicates separation).
	return oneProject + twoProject - distance
}
Example #4
0
func contactPoint(pOne *m.Vector3, dOne *m.Vector3, oneSize m.Real,
	pTwo *m.Vector3, dTwo *m.Vector3, twoSize m.Real, useOne bool) m.Vector3 {
	// If useOne is true, and the contact point is outside
	// the edge (in the case of an edge-face contact) then
	// we use one's midpoint, otherwise we use two's.
	//Vector3 toSt, cOne, cTwo;
	//real dpStaOne, dpStaTwo, dpOneTwo, smOne, smTwo;
	//real denom, mua, mub;

	smOne := dOne.SquareMagnitude()
	smTwo := dTwo.SquareMagnitude()
	dpOneTwo := dTwo.Dot(dOne)

	toSt := *pOne
	toSt.Sub(pTwo)
	dpStaOne := dOne.Dot(&toSt)
	dpStaTwo := dTwo.Dot(&toSt)

	denom := smOne*smTwo - dpOneTwo*dpOneTwo

	// Zero denominator indicates parrallel lines
	if m.RealAbs(denom) < m.Epsilon {
		if useOne {
			return *pOne
		}
		return *pTwo
	}

	mua := (dpOneTwo*dpStaTwo - smTwo*dpStaOne) / denom
	mub := (smOne*dpStaTwo - dpOneTwo*dpStaOne) / denom

	// If either of the edges has the nearest point out
	// of bounds, then the edges aren't crossed, we have
	// an edge-face contact. Our point is on the edge, which
	// we know from the useOne parameter.
	if mua > oneSize || mua < -oneSize || mub > twoSize || mub < -twoSize {
		if useOne {
			return *pOne
		}
		return *pTwo
	}

	cOne := *dOne
	cOne.MulWith(mua)
	cOne.Add(pOne)

	cTwo := *dTwo
	cTwo.MulWith(mub)
	cTwo.Add(pTwo)

	cOne.MulWith(0.5)
	cTwo.MulWith(0.5)
	cOne.Add(&cTwo)
	return cOne
}