//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,
}
}
//returns an AABB that holds both a and v.
func Expand(a AABB, v vect.Vect) AABB {
return AABB{
vect.Min(a.Lower, v),
vect.Max(a.Upper, v),
}
}
//returns an AABB that holds both a and b.
func CombinePtr(a, b *AABB) AABB {
return AABB{
vect.Min(a.Lower, b.Lower),
vect.Max(a.Upper, b.Upper),
}
}