extern float pia_area(const point_t *a, size_t na,
const point_t *b, size_t nb)
{
if ( (na < 3) || (nb < 3) ) return 0.0;
box_t B = {{ FLT_MAX, FLT_MAX},
{-FLT_MAX, -FLT_MAX}};
range(a, na, &B);
range(b, nb, &B);
const float
gamut = 500000000.0,
mid = gamut / 2.0;
float
rngx = B.max.x - B.min.x,
sclx = gamut / rngx,
rngy = B.max.y - B.min.y,
scly = gamut / rngy;
vertex_t ipa[na + 1], ipb[nb + 1];
fit(a, na, ipa, 0, sclx, scly, mid, B);
fit(b, nb, ipb, 2, sclx, scly, mid, B);
double ascale = (double)sclx * (double)scly;
int64_t s = 0;
for (size_t j = 0 ; j < na ; ++j)
{
for (size_t k = 0 ; k < nb ; ++k)
{
if ( ovl(ipa[j].rx, ipb[k].rx) && ovl(ipa[j].ry, ipb[k].ry) )
{
int64_t
a1 = -area(ipa[j].ip, ipb[k].ip, ipb[k + 1].ip),
a2 = area(ipa[j + 1].ip, ipb[k].ip, ipb[k + 1].ip);
bool o = (a1<0);
if (o == (a2<0))
{
int64_t
a3 = area(ipb[k].ip, ipa[j].ip, ipa[j + 1].ip),
a4 = -area(ipb[k + 1].ip, ipa[j].ip, ipa[j + 1].ip);
if ((a3<0) == (a4<0))
{
if (o)
cross(ipa + j, ipa + j + 1, ipb + k, ipb + k + 1, a1, a2, a3, a4, &s);
else
cross(ipb + k, ipb + k + 1, ipa + j, ipa + j + 1, a3, a4, a1, a2, &s);
}
}
}
}
}
inness(ipa, na, ipb, nb, &s);
inness(ipb, nb, ipa, na, &s);
return s / ascale;
}
double DkIntersectPoly::compute() {
// defines
gamut = 500000000;
minRange = nmc::DkVector(FLT_MAX, FLT_MAX);
maxRange = nmc::DkVector(-FLT_MAX, -FLT_MAX);
computeBoundingBox(vecA, &minRange, &maxRange);
computeBoundingBox(vecB, &minRange, &maxRange);
scale = maxRange - minRange;
if (scale.minCoord() == 0) return 0; //rechteck mit h�he oder breite = 0
scale.x = gamut / scale.x;
scale.y = gamut / scale.y;
float ascale = scale.x * scale.y;
// check input
if (vecA.size() < 3 || vecB.size() < 3) {
qDebug() << "The polygons must consist of at least 3 points but they are: (vecA: " << vecA.size() << ", vecB: " << vecB.size();
return 0;
}
// compute edges
std::vector<DkVertex> ipA;
std::vector<DkVertex> ipB;
getVertices(vecA, &ipA, 0);
getVertices(vecB, &ipB, 2);
for (unsigned int idxA = 0; idxA < ipA.size() - 1; idxA++) {
for (unsigned int idxB = 0; idxB < ipB.size() - 1; idxB++) {
if (ovl(ipA[idxA].rx, ipB[idxB].rx) && ovl(ipA[idxA].ry, ipB[idxB].ry)) {
int64 a1 = -area(ipA[idxA].ip, ipB[idxB].ip, ipB[idxB + 1].ip);
int64 a2 = area(ipA[idxA + 1].ip, ipB[idxB].ip, ipB[idxB + 1].ip);
if (a1 < 0 == a2 < 0) {
int64 a3 = area(ipB[idxB].ip, ipA[idxA].ip, ipA[idxA + 1].ip);
int64 a4 = -area(ipB[idxB + 1].ip, ipA[idxA].ip, ipA[idxA + 1].ip);
if (a3 < 0 == a4 < 0) {
if (a1 < 0) {
cross(ipA[idxA], ipA[idxA + 1], ipB[idxB], ipB[idxB + 1], (double)a1, (double)a2, (double)a3, (double)a4);
ipA[idxA].in++;
ipB[idxB].in--;
}
else {
cross(ipB[idxB], ipB[idxB + 1], ipA[idxA], ipA[idxA + 1], (double)a3, (double)a4, (double)a1, (double)a2);
ipA[idxA].in--;
ipB[idxB].in++;
}
}
}
}
}
}
inness(ipA, ipB);
inness(ipB, ipA);
double areaD = (double)interArea / (ascale + FLT_MIN);
return areaD;
}
