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[core, node] Re-implement "avoid edges" behavior for MapMode::Tile
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 - Fixes issue #12461.
 - Only implement "avoid edges" in MapMode::Tile since it's no longer relevant in Static or Continuous mode.
 - New: Force "avoid edges" to "true" for line labels, since in tile mode they'll always clip poorly at tile boundaries.
 - Remove unused "withinPlus0/inside" logic.
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@ChrisLoer
ChrisLoer committed Aug 20, 2018
1 parent 1b4398f commit 8ff7ac7
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Showing 4 changed files with 60 additions and 41 deletions.
32 changes: 8 additions & 24 deletions src/mbgl/layout/symbol_layout.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -258,11 +258,6 @@ void SymbolLayout::addFeature(const std::size_t layoutFeatureIndex,
const float textMaxBoxScale = tilePixelRatio * textMaxSize / glyphSize;
const float iconBoxScale = tilePixelRatio * layoutIconSize;
const float symbolSpacing = tilePixelRatio * layout.get<SymbolSpacing>();
// CJL: I'm not sure why SymbolPlacementType::Line -> avoidEdges = false. It seems redundant since
// getAnchors will already avoid generating anchors outside the tile bounds.
// However, SymbolPlacementType::LineCenter allows anchors outside tile boundaries, so its behavior
// here should match SymbolPlacement::Point
const bool avoidEdges = layout.get<SymbolAvoidEdges>() && layout.get<SymbolPlacement>() != SymbolPlacementType::Line;
const float textPadding = layout.get<TextPadding>() * tilePixelRatio;
const float iconPadding = layout.get<IconPadding>() * tilePixelRatio;
const float textMaxAngle = layout.get<TextMaxAngle>() * util::DEG2RAD;
Expand All @@ -274,25 +269,14 @@ void SymbolLayout::addFeature(const std::size_t layoutFeatureIndex,
IndexedSubfeature indexedFeature(feature.index, sourceLayer->getName(), bucketLeaderID, symbolInstances.size());

auto addSymbolInstance = [&] (const GeometryCoordinates& line, Anchor& anchor) {
// https://github.com/mapbox/vector-tile-spec/tree/master/2.1#41-layers
// +-------------------+ Symbols with anchors located on tile edges
// |(0,0) || are duplicated on neighbor tiles.
// | ||
// | || In continuous mode, to avoid overdraw we
// | || skip symbols located on the extent edges.
// | Tile || In still mode, we include the features in
// | || the buffers for both tiles and clip them
// | || at draw time.
// | ||
// +-------------------| In this scenario, the inner bounding box
// +-------------------+ is called 'withinPlus0', and the outer
// (extent,extent) is called 'inside'.
const bool withinPlus0 = anchor.point.x >= 0 && anchor.point.x < util::EXTENT && anchor.point.y >= 0 && anchor.point.y < util::EXTENT;
const bool inside = withinPlus0 || anchor.point.x == util::EXTENT || anchor.point.y == util::EXTENT;

if (avoidEdges && !inside) return;

if (mode == MapMode::Tile || withinPlus0) {
const bool anchorInsideTile = anchor.point.x >= 0 && anchor.point.x < util::EXTENT && anchor.point.y >= 0 && anchor.point.y < util::EXTENT;

if (mode == MapMode::Tile || anchorInsideTile) {
// For static/continuous rendering, only add symbols anchored within this tile:
// neighboring symbols will be added as part of the neighboring tiles.
// In tiled rendering mode, add all symbols in the buffers so that we can:
// (1) render symbols that overlap into this tile
// (2) approximate collision detection effects from neighboring symbols
symbolInstances.emplace_back(anchor, line, shapedTextOrientations, shapedIcon,
layout.evaluate(zoom, feature), layoutTextSize,
textBoxScale, textPadding, textPlacement, textOffset,
Expand Down
44 changes: 31 additions & 13 deletions src/mbgl/text/collision_index.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -62,6 +62,21 @@ bool CollisionIndex::isOffscreen(const CollisionBox& box) const {
bool CollisionIndex::isInsideGrid(const CollisionBox& box) const {
return box.px2 >= 0 && box.px1 < gridRightBoundary && box.py2 >= 0 && box.py1 < gridBottomBoundary;
}

CollisionTileBoundaries CollisionIndex::projectTileBoundaries(const mat4& posMatrix) const {
Point<float> topLeft = projectPoint(posMatrix, { 0, 0 });
Point<float> bottomRight = projectPoint(posMatrix, { util::EXTENT, util::EXTENT });

return {{ topLeft.x, topLeft.y, bottomRight.x, bottomRight.y }};

}

bool CollisionIndex::isInsideTile(const CollisionBox& box, const CollisionTileBoundaries& tileBoundaries) const {
// This check is only well defined when the tile boundaries are axis-aligned
// We are relying on it only being used in MapMode::Tile, where that is always the case

return box.px1 >= tileBoundaries[0] && box.py1 >= tileBoundaries[1] && box.px2 < tileBoundaries[2] && box.py2 < tileBoundaries[3];
}


std::pair<bool,bool> CollisionIndex::placeFeature(CollisionFeature& feature,
Expand All @@ -73,7 +88,8 @@ std::pair<bool,bool> CollisionIndex::placeFeature(CollisionFeature& feature,
const float fontSize,
const bool allowOverlap,
const bool pitchWithMap,
const bool collisionDebug) {
const bool collisionDebug,
const optional<CollisionTileBoundaries>& avoidEdges) {
if (!feature.alongLine) {
CollisionBox& box = feature.boxes.front();
const auto projectedPoint = projectAndGetPerspectiveRatio(posMatrix, box.anchor);
Expand All @@ -82,15 +98,17 @@ std::pair<bool,bool> CollisionIndex::placeFeature(CollisionFeature& feature,
box.py1 = box.y1 * tileToViewport + projectedPoint.first.y;
box.px2 = box.x2 * tileToViewport + projectedPoint.first.x;
box.py2 = box.y2 * tileToViewport + projectedPoint.first.y;


if (!isInsideGrid(box) ||
if ((avoidEdges && !isInsideTile(box, *avoidEdges)) ||
!isInsideGrid(box) ||
(!allowOverlap && collisionGrid.hitTest({{ box.px1, box.py1 }, { box.px2, box.py2 }}))) {
return { false, false };
}

return {true, isOffscreen(box)};
} else {
return placeLineFeature(feature, posMatrix, labelPlaneMatrix, textPixelRatio, symbol, scale, fontSize, allowOverlap, pitchWithMap, collisionDebug);
return placeLineFeature(feature, posMatrix, labelPlaneMatrix, textPixelRatio, symbol, scale, fontSize, allowOverlap, pitchWithMap, collisionDebug, avoidEdges);
}
}

Expand All @@ -103,7 +121,8 @@ std::pair<bool,bool> CollisionIndex::placeLineFeature(CollisionFeature& feature,
const float fontSize,
const bool allowOverlap,
const bool pitchWithMap,
const bool collisionDebug) {
const bool collisionDebug,
const optional<CollisionTileBoundaries>& avoidEdges) {

const auto tileUnitAnchorPoint = symbol.anchorPoint;
const auto projectedAnchor = projectAnchor(posMatrix, tileUnitAnchorPoint);
Expand Down Expand Up @@ -202,15 +221,14 @@ std::pair<bool,bool> CollisionIndex::placeLineFeature(CollisionFeature& feature,
entirelyOffscreen &= isOffscreen(circle);
inGrid |= isInsideGrid(circle);

if (!allowOverlap) {
if (collisionGrid.hitTest({{circle.px, circle.py}, circle.radius})) {
if (!collisionDebug) {
return {false, false};
} else {
// Don't early exit if we're showing the debug circles because we still want to calculate
// which circles are in use
collisionDetected = true;
}
if ((avoidEdges && !isInsideTile(circle, *avoidEdges)) ||
(!allowOverlap && collisionGrid.hitTest({{circle.px, circle.py}, circle.radius}))) {
if (!collisionDebug) {
return {false, false};
} else {
// Don't early exit if we're showing the debug circles because we still want to calculate
// which circles are in use
collisionDetected = true;
}
}
}
Expand Down
14 changes: 12 additions & 2 deletions src/mbgl/text/collision_index.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3,13 +3,18 @@
#include <mbgl/geometry/feature_index.hpp>
#include <mbgl/text/collision_feature.hpp>
#include <mbgl/util/grid_index.hpp>
#include <mbgl/util/optional.hpp>
#include <mbgl/map/transform_state.hpp>

#include <array>

namespace mbgl {

class PlacedSymbol;

struct TileDistance;

using CollisionTileBoundaries = std::array<float,4>;

class CollisionIndex {
public:
Expand All @@ -26,15 +31,19 @@ class CollisionIndex {
const float fontSize,
const bool allowOverlap,
const bool pitchWithMap,
const bool collisionDebug);
const bool collisionDebug,
const optional<CollisionTileBoundaries>& avoidEdges);

void insertFeature(CollisionFeature& feature, bool ignorePlacement, uint32_t bucketInstanceId);

std::unordered_map<uint32_t, std::vector<IndexedSubfeature>> queryRenderedSymbols(const ScreenLineString&) const;

CollisionTileBoundaries projectTileBoundaries(const mat4& posMatrix) const;

private:
bool isOffscreen(const CollisionBox&) const;
bool isInsideGrid(const CollisionBox&) const;
bool isInsideTile(const CollisionBox&, const CollisionTileBoundaries& tileBoundaries) const;

std::pair<bool,bool> placeLineFeature(CollisionFeature& feature,
const mat4& posMatrix,
Expand All @@ -45,7 +54,8 @@ class CollisionIndex {
const float fontSize,
const bool allowOverlap,
const bool pitchWithMap,
const bool collisionDebug);
const bool collisionDebug,
const optional<CollisionTileBoundaries>& avoidEdges);

float approximateTileDistance(const TileDistance& tileDistance, const float lastSegmentAngle, const float pixelsToTileUnits, const float cameraToAnchorDistance, const bool pitchWithMap);

Expand Down
11 changes: 9 additions & 2 deletions src/mbgl/text/placement.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -110,6 +110,13 @@ void Placement::placeLayerBucket(
auto partiallyEvaluatedTextSize = bucket.textSizeBinder->evaluateForZoom(state.getZoom());
auto partiallyEvaluatedIconSize = bucket.iconSizeBinder->evaluateForZoom(state.getZoom());

optional<CollisionTileBoundaries> avoidEdges;
if (mapMode == MapMode::Tile &&
(bucket.layout.get<style::SymbolAvoidEdges>() ||
bucket.layout.get<style::SymbolPlacement>() == style::SymbolPlacementType::Line)) {
avoidEdges = collisionIndex.projectTileBoundaries(posMatrix);
}

for (auto& symbolInstance : bucket.symbolInstances) {

if (seenCrossTileIDs.count(symbolInstance.crossTileID) == 0) {
Expand All @@ -133,7 +140,7 @@ void Placement::placeLayerBucket(
placedSymbol, scale, fontSize,
bucket.layout.get<style::TextAllowOverlap>(),
bucket.layout.get<style::TextPitchAlignment>() == style::AlignmentType::Map,
showCollisionBoxes);
showCollisionBoxes, avoidEdges);
placeText = placed.first;
offscreen &= placed.second;
}
Expand All @@ -147,7 +154,7 @@ void Placement::placeLayerBucket(
placedSymbol, scale, fontSize,
bucket.layout.get<style::IconAllowOverlap>(),
bucket.layout.get<style::IconPitchAlignment>() == style::AlignmentType::Map,
showCollisionBoxes);
showCollisionBoxes, avoidEdges);
placeIcon = placed.first;
offscreen &= placed.second;
}
Expand Down

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