bool SkOpAngle::checkParallel(const SkOpAngle& rh) const {
SkDVector scratch[2];
const SkDVector* sweep, * tweep;
if (!fUnorderedSweep) {
sweep = fSweep;
} else {
scratch[0] = fCurvePart[1] - fCurvePart[0];
sweep = &scratch[0];
}
if (!rh.fUnorderedSweep) {
tweep = rh.fSweep;
} else {
scratch[1] = rh.fCurvePart[1] - rh.fCurvePart[0];
tweep = &scratch[1];
}
double s0xt0 = sweep->crossCheck(*tweep);
if (tangentsDiverge(rh, s0xt0)) {
return s0xt0 < 0;
}
SkDVector m0 = fSegment->dPtAtT(midT()) - fCurvePart[0];
SkDVector m1 = rh.fSegment->dPtAtT(rh.midT()) - rh.fCurvePart[0];
double m0xm1 = m0.crossCheck(m1);
if (m0xm1 == 0) {
fUnorderable = true;
rh.fUnorderable = true;
return true;
}
return m0xm1 < 0;
}
// returns -1 if overlaps 0 if no overlap cw 1 if no overlap ccw
int SkOpAngle::convexHullOverlaps(const SkOpAngle& rh) const {
const SkDVector* sweep = fSweep;
const SkDVector* tweep = rh.fSweep;
double s0xs1 = sweep[0].crossCheck(sweep[1]);
double s0xt0 = sweep[0].crossCheck(tweep[0]);
double s1xt0 = sweep[1].crossCheck(tweep[0]);
bool tBetweenS = s0xs1 > 0 ? s0xt0 > 0 && s1xt0 < 0 : s0xt0 < 0 && s1xt0 > 0;
double s0xt1 = sweep[0].crossCheck(tweep[1]);
double s1xt1 = sweep[1].crossCheck(tweep[1]);
tBetweenS |= s0xs1 > 0 ? s0xt1 > 0 && s1xt1 < 0 : s0xt1 < 0 && s1xt1 > 0;
double t0xt1 = tweep[0].crossCheck(tweep[1]);
if (tBetweenS) {
return -1;
}
if ((s0xt0 == 0 && s1xt1 == 0) || (s1xt0 == 0 && s0xt1 == 0)) { // s0 to s1 equals t0 to t1
return -1;
}
bool sBetweenT = t0xt1 > 0 ? s0xt0 < 0 && s0xt1 > 0 : s0xt0 > 0 && s0xt1 < 0;
sBetweenT |= t0xt1 > 0 ? s1xt0 < 0 && s1xt1 > 0 : s1xt0 > 0 && s1xt1 < 0;
if (sBetweenT) {
return -1;
}
// if all of the sweeps are in the same half plane, then the order of any pair is enough
if (s0xt0 >= 0 && s0xt1 >= 0 && s1xt0 >= 0 && s1xt1 >= 0) {
return 0;
}
if (s0xt0 <= 0 && s0xt1 <= 0 && s1xt0 <= 0 && s1xt1 <= 0) {
return 1;
}
// if the outside sweeps are greater than 180 degress:
// first assume the inital tangents are the ordering
// if the midpoint direction matches the inital order, that is enough
SkDVector m0 = fSegment->dPtAtT(midT()) - fCurvePart[0];
SkDVector m1 = rh.fSegment->dPtAtT(rh.midT()) - rh.fCurvePart[0];
double m0xm1 = m0.crossCheck(m1);
if (s0xt0 > 0 && m0xm1 > 0) {
return 0;
}
if (s0xt0 < 0 && m0xm1 < 0) {
return 1;
}
if (tangentsDiverge(rh, s0xt0)) {
return s0xt0 < 0;
}
return m0xm1 < 0;
}