//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,
}
}
// Sets the vertices offset by the offset and calculates the PolygonAxes.
func (poly *PolygonShape) SetVerts(verts Vertices, offset vect.Vect) {
if verts == nil {
log.Printf("Error: no vertices passed!")
return
}
if verts.ValidatePolygon() == false {
log.Printf("Warning: vertices not valid")
}
numVerts := len(verts)
oldnumVerts := len(poly.Verts)
poly.NumVerts = numVerts
if oldnumVerts < numVerts {
//create new slices
poly.Verts = make(Vertices, numVerts)
poly.TVerts = make(Vertices, numVerts)
poly.Axes = make([]PolygonAxis, numVerts)
poly.TAxes = make([]PolygonAxis, numVerts)
} else {
//reuse old slices
poly.Verts = poly.Verts[:numVerts]
poly.TVerts = poly.TVerts[:numVerts]
poly.Axes = poly.Axes[:numVerts]
poly.TAxes = poly.TAxes[:numVerts]
}
for i := 0; i < numVerts; i++ {
a := vect.Add(offset, verts[i])
b := vect.Add(offset, verts[(i+1)%numVerts])
n := vect.Normalize(vect.Perp(vect.Sub(b, a)))
poly.Verts[i] = a
poly.Axes[i].N = n
poly.Axes[i].D = vect.Dot(n, a)
}
}