OpenSpace/modules/globebrowsing/tile/tileindex.cpp

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 * OpenSpace                                                                             *
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 * Copyright (c) 2014-2018                                                               *
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#include <modules/globebrowsing/tile/tileindex.h>

#include <modules/globebrowsing/geometry/geodetic2.h>

#include <ghoul/misc/dictionary.h>

#include <sstream>

namespace {
    constexpr const char* KeyLevel = "Level";
    constexpr const char* KeyX = "X";
    constexpr const char* KeyY = "Y";
} // namespace

namespace openspace::globebrowsing {

TileIndex::TileIndex(int x_, int y_, int level_)
    : x(x_)
    , y(y_)
    , level(level_)
{}

TileIndex::TileIndex(const Geodetic2& point, int level_)
    : level(level_)
{
    const int numIndicesAtLevel = 1 << level;
    const double u = 0.5 + point.lon / glm::two_pi<double>();
    const double v = 0.25 - point.lat / glm::two_pi<double>();
    const double xIndexSpace = u * numIndicesAtLevel;
    const double yIndexSpace = v * numIndicesAtLevel;

    x = static_cast<int>(floor(xIndexSpace));
    y = static_cast<int>(floor(yIndexSpace));
}

TileIndex::TileIndex(const ghoul::Dictionary& dict) {
    level = static_cast<int>(dict.value<double>(KeyLevel));
    x = static_cast<int>(dict.value<double>(KeyX));
    y = static_cast<int>(dict.value<double>(KeyY));
}

TileIndex TileIndex::child(Quad q) const {
    return TileIndex(2 * x + q % 2, 2 * y + q / 2, level + 1);
}

bool TileIndex::hasParent() const {
    return level > 0;
}

TileIndex TileIndex::parent() const {
    //ghoul_assert(level > 0, "tile at level 0 has no parent!");
    return TileIndex(x / 2, y / 2, level - 1);
}

bool TileIndex::isWestChild() const {
    return x % 2 == 0;
}

bool TileIndex::isEastChild() const {
    return x % 2 == 1;
}

bool TileIndex::isNorthChild() const {
    return y % 2 == 0;
}

bool TileIndex::isSouthChild() const {
    return y % 2 == 1;
}

bool TileIndex::operator==(const TileIndex& other) const {
    return (x == other.x) && (y == other.y) && (level == other.level);
}

TileIndex& TileIndex::operator--() {
    x /= 2;
    y /= 2;
    level--;

    return *this;
}

TileIndex TileIndex::operator--(int) {
    TileIndex tmp(*this);
    --(*this);

    return tmp;
}

TileIndex& TileIndex::operator-=(unsigned int levels) {
    x <<= levels;
    y <<= levels;
    level -= levels;

    return *this;
}

glm::vec2 TileIndex::positionRelativeParent() const {
    // In OpenGL, positive y direction is up
    return glm::vec2(isEastChild() ? 0.5f : 0.f, isNorthChild() ? 0.5f : 0.f);
}

TileIndex TileIndex::relatedTile(int deltaX, int deltaY) const {
    int indicesAtThisLevel = 1 << level;
    int newX = (indicesAtThisLevel + x + deltaX) % indicesAtThisLevel;
    int newY = (indicesAtThisLevel + y + deltaY) % indicesAtThisLevel;
    return TileIndex(newX, newY, level);
}

int TileIndex::manhattan(const TileIndex& other) const {
    ghoul_assert(level == other.level, "makes no sense if not on same level");

    return std::abs(x - other.x) + std::abs(y - other.y);
}

// Creates a hash which can be used as key in hash maps.
//
// +-------+------------+-------+------------+
// | USAGE | BIT RANGE  | #BITS | MAX VALUE  |
// +-------+------------+-------+------------+
// | level |   0 -  5   |   5   |         31 |
// |     x |   5 - 35   |  30   | 1073741824 |
// |     y |  35 - 64   |  29   |  536870912 |
// +-------+------------+-------+------------+

TileIndex::TileHashKey TileIndex::hashKey() const {
    TileHashKey key = 0LL;
    key |= level;
    key |= x << 5;
    key |= static_cast<TileHashKey>(y) << 35;

    return key;
}

std::string TileIndex::toString() const {
    std::stringstream ss;
    for (int i = level; i > 0; i--) {
        char digit = '0';
        int mask = 1 << (i - 1);
        if ((x & mask) != 0) {
            digit++;
        }
        if ((y & mask) != 0) {
            digit++;
            digit++;
        }
        ss << digit;
    }
    return ss.str();
}

std::ostream& operator<<(std::ostream& os, const TileIndex& ti) {
    os << "{ x = " << ti.x << ", y = " << ti.y << ", level = " << ti.level << " }";
    return os;
}

} // namespace openspace::globebrowsing