// compute repulsion field at interpolation point x, y and update v
func (f *RepulsionField) ComputeFieldRecursive(x, y float64, q *quadtree.Quadtree, coord quadtree.Coord, v *float64) {
Trace.Printf("ComputeFieldRecursive at %e %e, quadtree %p, coord %s, input v = %e\n", x, y, q, coord.String(), *v)
var body quadtree.Body
body.X = x
body.Y = y
// compute the node box size
level := coord.Level()
boxSize := 1.0 / math.Pow(2.0, float64(level)) // if level = 0, this is 1.0
node := &(q.Nodes[coord])
distToNode := getModuloDistanceBetweenBodies(&body, &(node.Body))
// avoid node with zero mass
if node.M == 0 {
return
}
// check if the COM of the node can be used
if (boxSize / distToNode) < BN_THETA {
*v += getRepulsionField(&body, &(node.Body))
} else {
if level < 8 {
// parse sub nodes
Trace.Printf("ComputeFieldRecursive go down at node %#v\n", node.Coord())
coordNW, coordNE, coordSW, coordSE := quadtree.NodesBelow(coord)
f.ComputeFieldRecursive(x, y, q, coordNW, v)
f.ComputeFieldRecursive(x, y, q, coordNE, v)
f.ComputeFieldRecursive(x, y, q, coordSW, v)
f.ComputeFieldRecursive(x, y, q, coordSE, v)
} else {
// parse bodies of the node
rank := 0
rankOfBody := -1
for b := node.First(); b != nil; b = b.Next() {
if *b != body {
dist := getModuloDistanceBetweenBodies(&body, b)
if dist == 0.0 {
var t testing.T
q.CheckIntegrity(&t)
// c1 := body.Coord()
// c2 := b.Coord()
Error.Printf("Problem at rank %d for body of rank %d on node %#v ",
rank, rankOfBody, *node)
}
// if distance is inferior to cutoff, return
if dist < f.cutoff {
*v = 0.0
return
} else {
*v += getRepulsionField(&body, b)
}
rank++
Trace.Printf("ComputeFieldRecursive at leaf %#v rank %d x %9.3f y %9.3f\n", b.Coord(), rank, x, y)
} else {
rankOfBody = rank
}
}
}
}
return
}
