static Point3f NURBSEvaluateSurface(int uOrder, const Float *uKnot, int ucp,
Float u, int vOrder, const Float *vKnot,
int vcp, Float v, const Homogeneous3 *cp,
Vector3f *dpdu, Vector3f *dpdv) {
Homogeneous3 *iso = ALLOCA(Homogeneous3, std::max(uOrder, vOrder));
int uOffset = KnotOffset(uKnot, uOrder, ucp, u);
int uFirstCp = uOffset - uOrder + 1;
Assert(uFirstCp >= 0 && uFirstCp + uOrder - 1 < ucp);
for (int i = 0; i < uOrder; ++i)
iso[i] = NURBSEvaluate(vOrder, vKnot, &cp[uFirstCp + i], vcp, ucp, v);
int vOffset = KnotOffset(vKnot, vOrder, vcp, v);
int vFirstCp = vOffset - vOrder + 1;
Assert(vFirstCp >= 0 && vFirstCp + vOrder - 1 < vcp);
Homogeneous3 P =
NURBSEvaluate(uOrder, uKnot, iso - uFirstCp, ucp, 1, u, dpdu);
if (dpdv) {
for (int i = 0; i < vOrder; ++i)
iso[i] = NURBSEvaluate(uOrder, uKnot, &cp[(vFirstCp + i) * ucp],
ucp, 1, u);
(void)NURBSEvaluate(vOrder, vKnot, iso - vFirstCp, vcp, 1, v, dpdv);
}
return Point3f(P.x / P.w, P.y / P.w, P.z / P.w);
}
static Point
NURBSEvaluateSurface(int uOrder, const float *uKnot, int ucp, float u,
int vOrder, const float *vKnot, int vcp, float v,
const Homogeneous3 *cp, Vector *dPdu, Vector *dPdv) {
Homogeneous3 *iso = (Homogeneous3 *)alloca(max(uOrder, vOrder) *
sizeof(Homogeneous3));
int uOffset = KnotOffset(uKnot, uOrder, ucp, u);
int uFirstCp = uOffset - uOrder + 1;
assert(uFirstCp >= 0 && uFirstCp + uOrder - 1 < ucp);
for (int i = 0; i < uOrder; ++i)
iso[i] = NURBSEvaluate(vOrder, vKnot, &cp[uFirstCp + i], vcp,
ucp, v);
int vOffset = KnotOffset(vKnot, vOrder, vcp, v);
int vFirstCp = vOffset - vOrder + 1;
assert(vFirstCp >= 0 && vFirstCp + vOrder - 1 < vcp);
Homogeneous3 P = NURBSEvaluate(uOrder, uKnot, iso - uFirstCp, ucp,
1, u, dPdu);
if (dPdv) {
for (int i = 0; i < vOrder; ++i)
iso[i] = NURBSEvaluate(uOrder, uKnot, &cp[(vFirstCp+i)*ucp], ucp,
1, u);
(void)NURBSEvaluate(vOrder, vKnot, iso - vFirstCp, vcp, 1, v, dPdv);
}
return Point(P.x/P.w, P.y/P.w, P.z/P.w);;
}
