diff options
| -rw-r--r-- | benchmark/util/tilecover.benchmark.cpp | 3 | ||||
| -rw-r--r-- | src/mbgl/util/tile_cover.cpp | 108 |
2 files changed, 73 insertions, 38 deletions
diff --git a/benchmark/util/tilecover.benchmark.cpp b/benchmark/util/tilecover.benchmark.cpp index e966875a65..cd9da54855 100644 --- a/benchmark/util/tilecover.benchmark.cpp +++ b/benchmark/util/tilecover.benchmark.cpp @@ -22,7 +22,8 @@ static void TileCoverPitchedViewport(benchmark::State& state) { Transform transform; transform.resize({ 512, 512 }); // slightly offset center so that tile order is better defined - transform.jumpTo(CameraOptions().withCenter(LatLng { 0.1, -0.1 }).withZoom(8.0).withBearing(5.0).withPitch(40.0)); + transform.jumpTo(CameraOptions().withCenter(LatLng { 0.1, -0.1 }).withPadding(EdgeInsets { 376, 0, 0, 0 }) + .withZoom(8.0).withBearing(5.0).withPitch(60.0)); std::size_t length = 0; while (state.KeepRunning()) { diff --git a/src/mbgl/util/tile_cover.cpp b/src/mbgl/util/tile_cover.cpp index 5189b79f26..ab4ec0afcc 100644 --- a/src/mbgl/util/tile_cover.cpp +++ b/src/mbgl/util/tile_cover.cpp @@ -39,15 +39,15 @@ static void scanSpans(edge e0, edge e1, int32_t ymin, int32_t ymax, ScanLine sca double y1 = ::fmin(ymax, std::ceil(e1.y1)); // sort edges by x-coordinate - if ((e0.x0 == e1.x0 && e0.y0 == e1.y0) ? - (e0.x0 + e1.dy / e0.dy * e0.dx < e1.x1) : - (e0.x1 - e1.dy / e0.dy * e0.dx < e1.x0)) { + double m0 = e0.dx / e0.dy; + double m1 = e1.dx / e1.dy; + double ySort = e0.y0 == e1.y0 ? std::min(e0.y1, e1.y1) : std::max(e0.y0, e1.y0); + if (e0.x0 - (e0.y0 - ySort) * m0 < e1.x0 - (e1.y0 - ySort) * m1) { std::swap(e0, e1); + std::swap(m0, m1); } // scan lines! - double m0 = e0.dx / e0.dy; - double m1 = e1.dx / e1.dy; double d0 = e0.dx > 0; // use y + 1 to compute x0 double d1 = e1.dx < 0; // use y + 1 to compute x1 for (int32_t y = y0; y < y1; y++) { @@ -57,22 +57,6 @@ static void scanSpans(edge e0, edge e1, int32_t ymin, int32_t ymax, ScanLine sca } } -// scan-line conversion -static void scanTriangle(const Point<double>& a, const Point<double>& b, const Point<double>& c, int32_t ymin, int32_t ymax, ScanLine& scanLine) { - edge ab = edge(a, b); - edge bc = edge(b, c); - edge ca = edge(c, a); - - // sort edges by y-length - if (ab.dy > bc.dy) { std::swap(ab, bc); } - if (ab.dy > ca.dy) { std::swap(ab, ca); } - if (bc.dy > ca.dy) { std::swap(bc, ca); } - - // scan span! scan span! - if (ab.dy) scanSpans(ca, ab, ymin, ymax, scanLine); - if (bc.dy) scanSpans(ca, bc, ymin, ymax, scanLine); -} - } // namespace namespace util { @@ -85,7 +69,7 @@ std::vector<UnwrappedTileID> tileCover(const Point<double>& tl, const Point<double>& bl, const Point<double>& c, int32_t z) { - const int32_t tiles = 1 << z; + const int32_t tiles = (1 << z) + 1; struct ID { int32_t x, y; @@ -96,30 +80,80 @@ std::vector<UnwrappedTileID> tileCover(const Point<double>& tl, auto scanLine = [&](int32_t x0, int32_t x1, int32_t y) { int32_t x; - if (y >= 0 && y <= tiles) { - for (x = x0; x < x1; ++x) { - const auto dx = x + 0.5 - c.x, dy = y + 0.5 - c.y; - t.emplace_back(ID{ x, y, dx * dx + dy * dy }); - } + for (x = x0; x < x1; ++x) { + const auto dx = x + 0.5 - c.x, dy = y + 0.5 - c.y; + t.emplace_back(ID { x, y, dx * dx + dy * dy }); } }; - // Divide the screen up in two triangles and scan each of them: - // \---+ - // | \ | - // +---\. - scanTriangle(tl, tr, br, 0, tiles, scanLine); - scanTriangle(br, bl, tl, 0, tiles, scanLine); + std::vector<Point<double>> bounds = {tl, tr, br, bl}; + while (bounds[0].y > min(min(bounds[1].y, bounds[2].y), bounds[3].y)) { + std::rotate(bounds.begin(), bounds.begin() + 1, bounds.end()); + } + /* + Keeping the clockwise winding order (abcd), we rotated convex quadrilateral + angles in such way that angle a (bounds[0]) is on top): + a + / \ + / b + / | + / c + / .... + / .. + d + This is an example: we handle also cases where d.y < c.y, d.y < b.y etc. + Split the scan to tree steps: + a + / \ (1) + / b + ----------------- + / | (2) + / c + ----------------- + / .... + / .. (3) + d + */ + edge ab = edge(bounds[0], bounds[1]); + edge ad = edge(bounds[0], bounds[3]); + + // Scan (1). + int32_t ymin = std::floor(bounds[0].y); + if (bounds[3].y < bounds[1].y) { std::swap(ab, ad); } + int32_t ymax = std::ceil(ab.y1); + if (ab.dy) { + scanSpans(ad, ab, std::max(0, ymin), std::min(tiles, ymax), scanLine); + ymin = ymax; + } + + // Scan (2). + // yCutLower is c or d, whichever is with lower y value. + float yCutLower = min(bounds[2].y, ad.y1); + ymax = std::ceil(yCutLower); + + // bc is edge opposite of ad. + edge bc = bounds[3].y < bounds[1].y ? edge(bounds[3], bounds[2]) : edge(bounds[1], bounds[2]); + if (bc.dy) { + scanSpans(ad, bc, std::max(0, ymin), std::min(tiles, ymax), scanLine); + ymin = ymax; + } else { + ymin = std::floor(yCutLower); + } + + // Scan (3) - the triangle at the bottom. + if (ad.y1 < bc.y1) { std::swap(ad, bc); } + ymax = std::ceil(ad.y1); + bc = edge({ bc.x1, bc.y1 }, { ad.x1, ad.y1 }); + if (bc.dy) { scanSpans(ad, bc, std::max(0, ymin), std::min(tiles, ymax), scanLine); } // Sort first by distance, then by x/y. std::sort(t.begin(), t.end(), [](const ID& a, const ID& b) { return std::tie(a.sqDist, a.x, a.y) < std::tie(b.sqDist, b.x, b.y); }); - // Erase duplicate tile IDs (they typically occur at the common side of both triangles). - t.erase(std::unique(t.begin(), t.end(), [](const ID& a, const ID& b) { - return a.x == b.x && a.y == b.y; - }), t.end()); + assert(t.end() == std::unique(t.begin(), t.end(), [](const ID& a, const ID& b) { + return a.x == b.x && a.y == b.y; + })); // no duplicates. std::vector<UnwrappedTileID> result; for (const auto& id : t) { |