C++ GeometryCoordinates::begin方法代码示例

Anchors resample(const GeometryCoordinates &line, const float offset, const float spacing,
        const float angleWindowSize, const float maxAngle, const float labelLength, const bool continuedLine, const bool placeAtMiddle) {

    const float halfLabelLength = labelLength / 2.0f;
    float lineLength = 0;
    for (auto it = line.begin(), end = line.end() - 1; it != end; it++) {
        lineLength += util::dist<float>(*(it), *(it + 1));
    }

    float distance = 0;
    float markedDistance = offset - spacing;

    Anchors anchors;

    assert(spacing > 0.0);

    int i = 0;
    for (auto it = line.begin(), end = line.end() - 1; it != end; it++, i++) {
        const GeometryCoordinate &a = *(it);
        const GeometryCoordinate &b = *(it + 1);

        const float segmentDist = util::dist<float>(a, b);
        const float angle = util::angle_to(b, a);

        while (markedDistance + spacing < distance + segmentDist) {
            markedDistance += spacing;

            float t = (markedDistance - distance) / segmentDist,
                  x = util::interpolate(float(a.x), float(b.x), t),
                  y = util::interpolate(float(a.y), float(b.y), t);

            // Check that the point is within the tile boundaries and that
            // the label would fit before the beginning and end of the line
            // if placed at this point.
            if (x >= 0 && x < util::EXTENT && y >= 0 && y < util::EXTENT &&
                    markedDistance - halfLabelLength >= 0.0f &&
                    markedDistance + halfLabelLength <= lineLength) {
                Anchor anchor(::round(x), ::round(y), angle, 0.5f, i);

                if (!angleWindowSize || checkMaxAngle(line, anchor, labelLength, angleWindowSize, maxAngle)) {
                    anchors.push_back(anchor);
                }
            }
        }

        distance += segmentDist;
    }

    if (!placeAtMiddle && anchors.empty() && !continuedLine) {
        // The first attempt at finding anchors at which labels can be placed failed.
        // Try again, but this time just try placing one anchor at the middle of the line.
        // This has the most effect for short lines in overscaled tiles, since the
        // initial offset used in overscaled tiles is calculated to align labels with positions in
        // parent tiles instead of placing the label as close to the beginning as possible.
        anchors = resample(line, distance / 2, spacing, angleWindowSize, maxAngle, labelLength, continuedLine, true);
    }

    return anchors;
}

bool lineIntersectsLine(const GeometryCoordinates& lineA, const GeometryCoordinates& lineB) {
    if (lineA.size() == 0 || lineB.size() == 0) return false;
    for (auto i = lineA.begin(); i != lineA.end() - 1; i++) {
        auto& a0 = *i;
        auto& a1 = *(i + 1);
        for (auto j = lineB.begin(); j != lineB.end() - 1; j++) {
            auto& b0 = *j;
            auto& b1 = *(j + 1);
            if (lineSegmentIntersectsLineSegment(a0, a1, b0, b1)) return true;
        }
    }
    return false;
}

bool polygonContainsPoint(const GeometryCoordinates& ring, const GeometryCoordinate& p) {
    bool c = false;
    for (auto i = ring.begin(), j = ring.end() - 1; i != ring.end(); j = i++) {
        auto& p1 = *i;
        auto& p2 = *j;
        if (((p1.y > p.y) != (p2.y > p.y)) && (p.x < float(p2.x - p1.x) * float(p.y - p1.y) / float(p2.y - p1.y) + p1.x)) {
            c = !c;
        }
    }
    return c;
}

bool pointIntersectsBufferedLine(const GeometryCoordinate& p, const GeometryCoordinates& line, const float radius) {
    const float radiusSquared = radius * radius;

    if (line.size() == 1) return util::distSqr<float>(p, line.at(0)) < radiusSquared;
    if (line.size() == 0) return false;

    for (auto i = line.begin() + 1; i != line.end(); i++) {
        // Find line segments that have a distance <= radius^2 to p
        // In that case, we treat the line as "containing point p".
        auto& v = *(i - 1);
        auto& w = *i;
        if (distToSegmentSquared(p, v, w) < radiusSquared) return true;
    }
    return false;
}