// Recalculates the global center of the circle and the the bounding box.
func (circle *CircleShape) update(xf transform.Transform) AABB {
//global center of the circle
center := xf.TransformVect(circle.Position)
circle.Tc = center
rv := vect.Vect{circle.Radius, circle.Radius}
return AABB{
vect.Sub(center, rv),
vect.Add(center, rv),
}
}
//Called to update N, Tn, Ta, Tb and the the bounding box.
func (segment *SegmentShape) update(xf transform.Transform) AABB {
a := xf.TransformVect(segment.A)
b := xf.TransformVect(segment.B)
segment.Ta = a
segment.Tb = b
segment.N = vect.Perp(vect.Normalize(vect.Sub(segment.B, segment.A)))
segment.Tn = xf.RotateVect(segment.N)
rv := vect.Vect{segment.Radius, segment.Radius}
min := vect.Min(a, b)
min.Sub(rv)
max := vect.Max(a, b)
max.Add(rv)
return AABB{
min,
max,
}
}