C++ AABB::clip方法代码示例

AABB Triangle::getClippedAABB(const Point *positions, const AABB &aabb) const {
    /* Reserve room for some additional vertices */
    Point3d vertices1[MAX_VERTS], vertices2[MAX_VERTS];
    int nVertices = 3;

    /* The kd-tree code will frequently call this function with
       almost-collapsed AABBs. It's extremely important not to introduce
       errors in such cases, otherwise the resulting tree will incorrectly
       remove triangles from the associated nodes. Hence, do the
       following computation in double precision! */
    for (int i=0; i<3; ++i)
        vertices1[i] = Point3d(positions[idx[i]]);

    for (int axis=0; axis<3; ++axis) {
        nVertices = sutherlandHodgman(vertices1, nVertices, vertices2, axis, aabb.min[axis], true);
        nVertices = sutherlandHodgman(vertices2, nVertices, vertices1, axis, aabb.max[axis], false);
    }

    AABB result;
    for (int i=0; i<nVertices; ++i) {
#if defined(SINGLE_PRECISION)
        for (int j=0; j<3; ++j) {
            /* Now this is really paranoid! */
            double pos_d = vertices1[i][j];
            float  pos_f = (float) pos_d;
            float  pos_roundedDown, pos_roundedUp;

            if (pos_f < pos_d) {
                /* Float value is too small */
                pos_roundedDown = pos_f;
                pos_roundedUp = nextafterf(pos_f,
                                           std::numeric_limits<float>::infinity());
            } else if (pos_f > pos_d) {
                /* Float value is too large */
                pos_roundedUp = pos_f;
                pos_roundedDown = nextafterf(pos_f,
                                             -std::numeric_limits<float>::infinity());
            } else {
                /* Double value is exactly representable */
                pos_roundedDown = pos_roundedUp = pos_f;
            }

            result.min[j] = std::min(result.min[j], pos_roundedDown);
            result.max[j] = std::max(result.max[j], pos_roundedUp);
        }
#else
        result.expandBy(vertices1[i]);
#endif
    }
    result.clip(aabb);

    return result;
}

void AABBTree::findBestPlane(const vector<Triangle>& T, const AABB& V, SplittingPlane& p_est, float& C_est, PlaneSide& pside_est)
{
    C_est = numeric_limits<float>::max();

    for(int axis=0; axis<3; axis++) {
        vector<SplitEvent> events;
        events.reserve(T.size()*2);

        for(int i=0; i<T.size(); ++i) {
            auto ti = T[i];
            AABB tibb = V.clip(ti);

            if(tibb.isPlanar()) {
                events.push_back(SplitEvent(ti, axis, tibb.minPos(axis), SplitEvent::LyingOnPlane));
            }
            else {
                events.push_back(SplitEvent(ti, axis, tibb.minPos(axis), SplitEvent::StartingOnPlane));
                events.push_back(SplitEvent(ti, axis, tibb.maxPos(axis), SplitEvent::EndingOnPlane));
            }
        }

        // sort the events
        sort(events.begin(), events.end());

        // test every candidate plane
        int NL = 0, NP = 0, NR = T.size();
        for(int i=0; i<events.size(); ++i) {
            auto p = events[i].p;

            int tLyingOnPlane = 0, tEndingOnPlane=0, tStartingOnPlane=0;
            while( i<events.size() && events[i].p.pe == p.pe && events[i].type == SplitEvent::EndingOnPlane ) {
                ++tEndingOnPlane;
                i++;
            }
            while( i<events.size() && events[i].p.pe == p.pe && events[i].type == SplitEvent::LyingOnPlane ) {
                ++tLyingOnPlane;
                i++;
            }
            while( i<events.size() && events[i].p.pe == p.pe && events[i].type == SplitEvent::StartingOnPlane ) {
                ++tStartingOnPlane;
                i++;
            }

            NP = tLyingOnPlane;
            NR -= tLyingOnPlane;
            NR -= tEndingOnPlane;

            float C;
            PlaneSide ps;
            SAH(p, V, NL, NR, NP, C, ps);

            if(C < C_est) {
                C_est = C;
                p_est = p;
                pside_est = ps;
            }
            NL += tStartingOnPlane;
            NL += tLyingOnPlane;
            NP = 0;
        }
    }
}

AABB Shape::getClippedAABB(const AABB &box) const {
	AABB result = getAABB();
	result.clip(box);
	return result;
}