diff options
Diffstat (limited to 'src/mbgl/text/collision_feature.cpp')
-rw-r--r-- | src/mbgl/text/collision_feature.cpp | 81 |
1 files changed, 25 insertions, 56 deletions
diff --git a/src/mbgl/text/collision_feature.cpp b/src/mbgl/text/collision_feature.cpp index 3eb08da8d1..6d6f2aabc7 100644 --- a/src/mbgl/text/collision_feature.cpp +++ b/src/mbgl/text/collision_feature.cpp @@ -13,8 +13,9 @@ CollisionFeature::CollisionFeature(const GeometryCoordinates& line, const float padding, const style::SymbolPlacementType placement, IndexedSubfeature indexedFeature_, - const AlignmentType alignment) - : indexedFeature(std::move(indexedFeature_)) { + const float overscaling) + : indexedFeature(std::move(indexedFeature_)) + , alongLine(placement == style::SymbolPlacementType::Line) { if (top == 0 && bottom == 0 && left == 0 && right == 0) return; const float y1 = top * boxScale - padding; @@ -22,7 +23,7 @@ CollisionFeature::CollisionFeature(const GeometryCoordinates& line, const float x1 = left * boxScale - padding; const float x2 = right * boxScale + padding; - if (placement == style::SymbolPlacementType::Line) { + if (alongLine) { float height = y2 - y1; const double length = x2 - x1; @@ -31,29 +32,26 @@ CollisionFeature::CollisionFeature(const GeometryCoordinates& line, height = std::max(10.0f * boxScale, height); GeometryCoordinate anchorPoint = convertPoint<int16_t>(anchor.point); - - if (alignment == AlignmentType::Straight) { - // used for icon labels that are aligned with the line, but don't curve along it - const GeometryCoordinate vector = convertPoint<int16_t>(util::unit(convertPoint<double>(line[anchor.segment + 1] - line[anchor.segment])) * length); - const GeometryCoordinates newLine({ anchorPoint - vector, anchorPoint + vector }); - bboxifyLabel(newLine, anchorPoint, 0, length, height); - } else { - // used for text labels that curve along a line - bboxifyLabel(line, anchorPoint, anchor.segment, length, height); - } + bboxifyLabel(line, anchorPoint, anchor.segment, length, height, overscaling); } else { - boxes.emplace_back(anchor.point, Point<float>{ 0, 0 }, x1, y1, x2, y2, std::numeric_limits<float>::infinity()); + boxes.emplace_back(anchor.point, Point<float>{ 0, 0 }, x1, y1, x2, y2); } } void CollisionFeature::bboxifyLabel(const GeometryCoordinates& line, GeometryCoordinate& anchorPoint, - const int segment, const float labelLength, const float boxSize) { + const int segment, const float labelLength, const float boxSize, const float overscaling) { const float step = boxSize / 2; const int nBoxes = std::floor(labelLength / step); - // We calculate line collision boxes out to 300% of what would normally be our + // We calculate line collision circles out to 300% of what would normally be our // max size, to allow collision detection to work on labels that expand as // they move into the distance - const int nPitchPaddingBoxes = std::floor(nBoxes / 2); + // Vertically oriented labels in the distant field can extend past this padding + // This is a noticeable problem in overscaled tiles where the pitch 0-based + // symbol spacing will put labels very close together in a pitched map. + // To reduce the cost of adding extra collision circles, we slowly increase + // them for overscaled tiles. + const float overscalingPaddingFactor = 1 + .4 * std::log(overscaling) / std::log(2); + const int nPitchPaddingBoxes = std::floor(nBoxes * overscalingPaddingFactor / 2); // offset the center of the first box by half a box so that the edge of the // box is at the edge of the label. @@ -124,47 +122,18 @@ void CollisionFeature::bboxifyLabel(const GeometryCoordinates& line, GeometryCoo p0.x + segmentBoxDistance / segmentLength * (p1.x - p0.x), p0.y + segmentBoxDistance / segmentLength * (p1.y - p0.y) }; - - // Distance from label anchor point to inner (towards center) edge of this box - // The tricky thing here is that box positioning doesn't change with scale, - // but box size does change with scale. - // Technically, distanceToInnerEdge should be: - // Math.max(Math.abs(boxDistanceToAnchor - firstBoxOffset) - (step / scale), 0); - // But using that formula would make solving for maxScale more difficult, so we - // approximate with scale=2. - // This makes our calculation spot-on at scale=2, and on the conservative side for - // lower scales - const float distanceToInnerEdge = std::max(std::fabs(boxDistanceToAnchor - firstBoxOffset) - step / 2, 0.0f); - float maxScale = util::division(labelLength / 2, distanceToInnerEdge, std::numeric_limits<float>::infinity()); - - // The box maxScale calculations are designed to be conservative on collisions in the scale range - // [1,2]. At scale=1, each box has 50% overlap, and at scale=2, the boxes are lined up edge - // to edge (beyond scale 2, gaps start to appear, which could potentially allow missed collisions). - // We add "pitch padding" boxes to the left and right to handle effective underzooming - // (scale < 1) when labels are in the distance. The overlap approximation could cause us to use - // these boxes when the scale is greater than 1, but we prevent that because we know - // they're only necessary for scales less than one. - // This preserves the pre-pitch-padding behavior for unpitched maps. - if (i < 0 || i >= nBoxes) { - maxScale = std::min(maxScale, 0.99f); - } - - boxes.emplace_back(boxAnchor, boxAnchor - convertPoint<float>(anchorPoint), -boxSize / 2, -boxSize / 2, boxSize / 2, boxSize / 2, maxScale); + + // If the box is within boxSize of the anchor, force the box to be used + // (so even 0-width labels use at least one box) + // Otherwise, the .8 multiplication gives us a little bit of conservative + // padding in choosing which boxes to use (see CollisionIndex#placedCollisionCircles) + const float paddedAnchorDistance = std::abs(boxDistanceToAnchor - firstBoxOffset) < step ? + 0 : + (boxDistanceToAnchor - firstBoxOffset) * 0.8; + + boxes.emplace_back(boxAnchor, boxAnchor - convertPoint<float>(anchorPoint), -boxSize / 2, -boxSize / 2, boxSize / 2, boxSize / 2, paddedAnchorDistance, boxSize / 2); } } -float CollisionBox::adjustedMaxScale(const std::array<float, 4>& rotationMatrix, const float yStretch) const { - // When the map is pitched the distance covered by a line changes. - // Adjust the max scale by (approximatePitchedLength / approximateRegularLength) - // to compensate for this. - const Point<float> rotatedOffset = util::matrixMultiply(rotationMatrix, offset); - const float xSqr = rotatedOffset.x * rotatedOffset.x; - const float ySqr = rotatedOffset.y * rotatedOffset.y; - const float yStretchSqr = ySqr * yStretch * yStretch; - const float adjustmentFactor = xSqr + ySqr != 0 ? - std::sqrt((xSqr + yStretchSqr) / (xSqr + ySqr)) : - 1.0f; - return maxScale * adjustmentFactor; -} } // namespace mbgl |