static bool IsClockwise(const DirectX::XMFLOAT3 *vertex, int num_verts, const FbxVector4 &polygon_normal)
{
// Compute a normal using two edges of the triangle
FbxVector4 edge_1(vertex[1].x - vertex[0].x, vertex[1].y - vertex[0].y, vertex[1].z - vertex[0].z);
FbxVector4 edge_2(vertex[2].x - vertex[0].x, vertex[2].y - vertex[0].y, vertex[2].z - vertex[0].z);
FbxVector4 normal = edge_1.CrossProduct(edge_2);
// Dot product between computed normal and supplied normal will reveal winding
double dot = polygon_normal.DotProduct(normal);
return dot < 0;
}
/* mend face with colinear vertices */
static int mendface (face *f)
{
edge *e, *h, *x, *y, *z, *w, *o;
double u [3], v [3], d, l [2];
double *a, *b, *c;
face *g;
for (e = f->e; e; e = e->n)
{
a = e->v [0];
b = e->v [1];
if (!(c = otherv (f, a, b))) return 0;
SUB (b, a, u);
SUB (c, a, v);
l[0] = LEN (u);
l[1] = LEN (v);
d = DOT (u, v);
if (d >= 0 && l[1] <= l[0]) break; /* c in [a, b] */
}
if (e)
{
a = c;
g = e->f;
if (!(h = othere (g, f))) return 0;
if (!(b = otherv (g, h->v[0], h->v[1]))) return 0;
if (!(x = edge_0 (f, a))) return 0;
if (!(y = edge_1 (g, b))) return 0;
if (!(z = edge_0 (g, b))) return 0;
if (!(w = edge_1 (f, a))) return 0;
if (!(o = othere (y->f, g))) return 0;
o->f = f;
if (!(o = othere (w->f, f))) return 0;
o->f = g;
e->v [0] = b;
e->v [1] = a;
h->v [0] = a;
h->v [1] = b;
e->n = NULL;
y->n = e;
x->n = y;
f->e = x;
h->n = NULL;
w->n = h;
z->n = w;
g->e = z;
#if GEOMDEBUG
ASSERT_DEBUG (setplane (f), "Zero normal (when mending face)");
ASSERT_DEBUG (setplane (g), "Zero normal (when mending face)");
#else
if (!(setplane (f) && setplane (g))) return 0;
#endif
}
#if GEOMDEBUG
else
{
ASSERT_DEBUG (0, "Face mending failed");
}
#else
else return 0;
