func (arb *Arbiter) preStep2(inv_dt, slop, bias float32) {
a := arb.ShapeA.Body
b := arb.ShapeB.Body
for i := 0; i < arb.NumContacts; i++ {
con := arb.Contacts[i]
// Calculate the offsets.
con.r1 = vect.Sub(con.p, a.p)
con.r2 = vect.Sub(con.p, b.p)
//con.Normal = vect.Vect{-1,0}
// Calculate the mass normal and mass tangent.
con.nMass = 1.0 / k_scalar(a, b, con.r1, con.r2, con.n)
con.tMass = 1.0 / k_scalar(a, b, con.r1, con.r2, vect.Perp(con.n))
// Calculate the target bias velocity.
con.bias = -bias * inv_dt * vect.FMin(0.0, con.dist+slop)
con.jBias = 0.0
//con.jtAcc = 0
//con.jnAcc = 0
//fmt.Println("con.dist", con.dist)
// Calculate the target bounce velocity.
con.bounce = normal_relative_velocity(a, b, con.r1, con.r2, con.n) * arb.e
}
}
func (poly *PolygonShape) valueOnAxis(n vect.Vect, d float32) float32 {
verts := poly.TVerts
min := vect.Dot(n, verts[0])
for i := 1; i < poly.NumVerts; i++ {
min = vect.FMin(min, vect.Dot(n, verts[i]))
}
//fmt.Println(min, d)
return min - d
}
func MergedAreaPtr(a, b *AABB) float32 {
return (vect.FMax(a.Upper.X, b.Upper.X) - vect.FMin(a.Lower.X, b.Lower.X)) * (vect.FMax(a.Upper.Y, b.Upper.Y) - vect.FMin(a.Lower.Y, b.Lower.Y))
}
func segValueOnAxis(seg *SegmentShape, n vect.Vect, d float32) float32 {
a := vect.Dot(n, seg.Ta) - seg.Radius
b := vect.Dot(n, seg.Tb) - seg.Radius
return vect.FMin(a, b) - d
}