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}
else if (e.polyEdge[1] != 0xff)
{
unsigned short* p0 = &polys[e.poly[0]*MAX_VERTS_PER_POLY*2];
p0[MAX_VERTS_PER_POLY + e.polyEdge[0]] = 0x8000 | (unsigned short)e.polyEdge[1];
}
}
return true;
}
// Last time I checked the if version got compiled using cmov, which was a lot faster than module (with idiv).
inline int prev(int i, int n) { return i-1 >= 0 ? i-1 : n-1; }
inline int next(int i, int n) { return i+1 < n ? i+1 : 0; }
inline int area2(const unsigned char* a, const unsigned char* b, const unsigned char* c)
{
return ((int)b[0] - (int)a[0]) * ((int)c[2] - (int)a[2]) - ((int)c[0] - (int)a[0]) * ((int)b[2] - (int)a[2]);
}
// Exclusive or: true iff exactly one argument is true.
// The arguments are negated to ensure that they are 0/1
// values. Then the bitwise Xor operator may apply.
// (This idea is due to Michael Baldwin.)
inline bool xorb(bool x, bool y)
{
return !x ^ !y;
}
// Returns true iff c is strictly to the left of the directed
// line through a to b.
inline bool left(const unsigned char* a, const unsigned char* b, const unsigned char* c)
{
return area2(a, b, c) < 0;
}
inline bool leftOn(const unsigned char* a, const unsigned char* b, const unsigned char* c)
{
return area2(a, b, c) <= 0;
}
inline bool collinear(const unsigned char* a, const unsigned char* b, const unsigned char* c)
{
return area2(a, b, c) == 0;
}
// Returns true iff ab properly intersects cd: they share
// a point interior to both segments. The properness of the
// intersection is ensured by using strict leftness.
static bool intersectProp(const unsigned char* a, const unsigned char* b,
const unsigned char* c, const unsigned char* d)
{
// Eliminate improper cases.
if (collinear(a,b,c) || collinear(a,b,d) ||
collinear(c,d,a) || collinear(c,d,b))
return false;
return xorb(left(a,b,c), left(a,b,d)) && xorb(left(c,d,a), left(c,d,b));
}
// Returns T iff (a,b,c) are collinear and point c lies
// on the closed segement ab.
static bool between(const unsigned char* a, const unsigned char* b, const unsigned char* c)
{
if (!collinear(a, b, c))
return false;
// If ab not vertical, check betweenness on x; else on y.
if (a[0] != b[0])
return ((a[0] <= c[0]) && (c[0] <= b[0])) || ((a[0] >= c[0]) && (c[0] >= b[0]));
else
return ((a[2] <= c[2]) && (c[2] <= b[2])) || ((a[2] >= c[2]) && (c[2] >= b[2]));
}
// Returns true iff segments ab and cd intersect, properly or improperly.
static bool intersect(const unsigned char* a, const unsigned char* b,
const unsigned char* c, const unsigned char* d)
{
if (intersectProp(a, b, c, d))
return true;
else if (between(a, b, c) || between(a, b, d) ||
between(c, d, a) || between(c, d, b))
return true;
else
return false;
}
static bool vequal(const unsigned char* a, const unsigned char* b)
{
return a[0] == b[0] && a[2] == b[2];
}
// Returns T iff (v_i, v_j) is a proper internal *or* external
// diagonal of P, *ignoring edges incident to v_i and v_j*.
static bool diagonalie(int i, int j, int n, const unsigned char* verts, const unsigned short* indices)
{
const unsigned char* d0 = &verts[(indices[i] & 0x7fff) * 4];
const unsigned char* d1 = &verts[(indices[j] & 0x7fff) * 4];