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[core] In tile mode, place labels from tile borders first
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@pozdnyakov
pozdnyakov committed Jan 7, 2020
1 parent 1e5cbd7 commit 5de2585
Showing 1 changed file with 88 additions and 53 deletions.
141 changes: 88 additions & 53 deletions src/mbgl/text/placement.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -142,10 +142,9 @@ Point<float> calculateVariableLayoutOffset(style::SymbolAnchorType anchor,
}
} // namespace

void Placement::placeBucket(
const SymbolBucket& bucket,
const BucketPlacementParameters& params,
std::set<uint32_t>& seenCrossTileIDs) {
void Placement::placeBucket(const SymbolBucket& bucket,
const BucketPlacementParameters& params,
std::set<uint32_t>& seenCrossTileIDs) {
const auto& layout = *bucket.layout;
const auto& renderTile = params.tile;
const auto& state = collisionIndex.getTransformState();
Expand All @@ -158,11 +157,12 @@ void Placement::placeBucket(
state.matrixFor(posMatrix, renderTile.id);
matrix::multiply(posMatrix, params.projMatrix, posMatrix);

mat4 textLabelPlaneMatrix = getLabelPlaneMatrix(posMatrix,
layout.get<style::TextPitchAlignment>() == style::AlignmentType::Map,
layout.get<style::TextRotationAlignment>() == style::AlignmentType::Map,
state,
pixelsToTileUnits);
mat4 textLabelPlaneMatrix =
getLabelPlaneMatrix(posMatrix,
layout.get<style::TextPitchAlignment>() == style::AlignmentType::Map,
layout.get<style::TextRotationAlignment>() == style::AlignmentType::Map,
state,
pixelsToTileUnits);

mat4 iconLabelPlaneMatrix = getLabelPlaneMatrix(posMatrix,
layout.get<style::IconPitchAlignment>() == style::AlignmentType::Map,
Expand All @@ -182,6 +182,7 @@ void Placement::placeBucket(
layout.get<style::SymbolPlacement>() == style::SymbolPlacementType::Line)) {
avoidEdges = tileBorders;
}
const bool stickToFirstAnchor = tileBorders && !avoidEdges;

const bool textAllowOverlap = layout.get<style::TextAllowOverlap>();
const bool iconAllowOverlap = layout.get<style::IconAllowOverlap>();
Expand Down Expand Up @@ -243,7 +244,7 @@ void Placement::placeBucket(
}
};

const auto placeTextForPlacementModes = [&] (auto& placeHorizontalFn, auto& placeVerticalFn) {
const auto placeTextForPlacementModes = [&](auto& placeHorizontalFn, auto& placeVerticalFn) {
if (bucket.allowVerticalPlacement && symbolInstance.writingModes & WritingModeType::Vertical) {
assert(!bucket.placementModes.empty());
for (auto& placementMode : bucket.placementModes) {
Expand Down Expand Up @@ -293,7 +294,8 @@ void Placement::placeBucket(

const auto placeVertical = [&] {
if (bucket.allowVerticalPlacement && symbolInstance.verticalTextCollisionFeature) {
return placeFeature(*symbolInstance.verticalTextCollisionFeature, style::TextWritingModeType::Vertical);
return placeFeature(*symbolInstance.verticalTextCollisionFeature,
style::TextWritingModeType::Vertical);
}
return std::pair<bool, bool>{false, false};
};
Expand Down Expand Up @@ -340,8 +342,6 @@ void Placement::placeBucket(
std::pair<bool, bool> placedFeature = {false, false};
const size_t anchorsSize = variableTextAnchors.size();
const size_t placementAttempts = textAllowOverlap ? anchorsSize * 2 : anchorsSize;
const bool stickToFirstAnchor = tileBorders && !avoidEdges;

for (size_t i = 0u; i < placementAttempts; ++i) {
auto anchor = variableTextAnchors[i % anchorsSize];
const auto& avoidEdgesForVariableAnchor =
Expand Down Expand Up @@ -553,6 +553,44 @@ void Placement::placeBucket(
for (auto it = sortedSymbols.rbegin(); it != sortedSymbols.rend(); ++it) {
placeSymbol(*it);
}
} else if (stickToFirstAnchor) {
// In this case we first try to place symbols, which intersects the tile borders, so that
// those symbols will remain even if each tile is handled independently.
assert(mapMode == MapMode::Tile);
const auto& symbolInstances = bucket.symbolInstances;
std::vector<std::reference_wrapper<const SymbolInstance>> sorted(symbolInstances.begin(),
symbolInstances.end());
optional<style::TextVariableAnchorType> variableAnchor;
if (!variableTextAnchors.empty()) variableAnchor = variableTextAnchors.front();

auto intersectsTileBorder = [&](const SymbolInstance& symbol) -> bool {
if (symbol.textCollisionFeature.boxes.empty()) return false;
Point<float> offset{};
if (variableAnchor) {
const CollisionBox& textBox = symbol.textCollisionFeature.boxes.front();
float width = textBox.x2 - textBox.x1;
float height = textBox.y2 - textBox.y1;
offset = calculateVariableLayoutOffset(*variableAnchor,
width,
height,
symbol.variableTextOffset,
symbol.textBoxScale,
rotateWithMap,
pitchWithMap,
state.getBearing());
}
return collisionIndex.featureIntersectsTileBorders(
symbol.textCollisionFeature, offset, posMatrix, pixelRatio, *tileBorders);
};

std::stable_sort(sorted.begin(), sorted.end(), [&](const SymbolInstance& a, const SymbolInstance& b) {
return intersectsTileBorder(a) && !intersectsTileBorder(b);
});

for (const SymbolInstance& symbol : sorted) {
placeSymbol(symbol);
}

} else {
for (const SymbolInstance& symbol : bucket.symbolInstances) {
placeSymbol(symbol);
Expand Down Expand Up @@ -891,7 +929,8 @@ void Placement::updateBucketOpacities(SymbolBucket& bucket,
}
}
if (symbolInstance.hasIcon()) {
const auto& opacityVertex = SymbolIconProgram::opacityVertex(opacityState.icon.placed, opacityState.icon.opacity);
const auto& opacityVertex =
SymbolIconProgram::opacityVertex(opacityState.icon.placed, opacityState.icon.opacity);
auto& iconBuffer = symbolInstance.hasSdfIcon() ? bucket.sdfIcon : bucket.icon;

if (symbolInstance.placedIconIndex) {
Expand All @@ -904,7 +943,7 @@ void Placement::updateBucketOpacities(SymbolBucket& bucket,
iconBuffer.placedSymbols[*symbolInstance.placedVerticalIconIndex].hidden = opacityState.isHidden();
}
}

auto updateIconCollisionBox = [&](const auto& feature, const bool placed, const Point<float>& shift) {
if (feature.alongLine) {
return;
Expand All @@ -913,45 +952,41 @@ void Placement::updateBucketOpacities(SymbolBucket& bucket,
bucket.iconCollisionBox->dynamicVertices.extend(feature.boxes.size() * 4, dynamicVertex);
};

auto updateTextCollisionBox = [this,
&bucket,
&symbolInstance,
&state,
variablePlacement,
rotateWithMap,
pitchWithMap](const auto& feature, const bool placed) {
Point<float> shift{0.0f, 0.0f};
if (feature.alongLine) {
return shift;
}
bool used = true;
if (variablePlacement) {
auto foundOffset = variableOffsets.find(symbolInstance.crossTileID);
if (foundOffset != variableOffsets.end()) {
const VariableOffset& variableOffset = foundOffset->second;
// This will show either the currently placed position or the last
// successfully placed position (so you can visualize what collision
// just made the symbol disappear, and the most likely place for the
// symbol to come back)
shift = calculateVariableLayoutOffset(variableOffset.anchor,
variableOffset.width,
variableOffset.height,
variableOffset.offset,
variableOffset.textBoxScale,
rotateWithMap,
pitchWithMap,
state.getBearing());
} else {
// No offset -> this symbol hasn't been placed since coming on-screen
// No single box is particularly meaningful and all of them would be too noisy
// Use the center box just to show something's there, but mark it "not used"
used = false;
auto updateTextCollisionBox =
[this, &bucket, &symbolInstance, &state, variablePlacement, rotateWithMap, pitchWithMap](
const auto& feature, const bool placed) {
Point<float> shift{0.0f, 0.0f};
if (feature.alongLine) {
return shift;
}
}
const auto& dynamicVertex = CollisionBoxProgram::dynamicVertex(placed, !used, shift);
bucket.textCollisionBox->dynamicVertices.extend(feature.boxes.size() * 4, dynamicVertex);
return shift;
};
bool used = true;
if (variablePlacement) {
auto foundOffset = variableOffsets.find(symbolInstance.crossTileID);
if (foundOffset != variableOffsets.end()) {
const VariableOffset& variableOffset = foundOffset->second;
// This will show either the currently placed position or the last
// successfully placed position (so you can visualize what collision
// just made the symbol disappear, and the most likely place for the
// symbol to come back)
shift = calculateVariableLayoutOffset(variableOffset.anchor,
variableOffset.width,
variableOffset.height,
variableOffset.offset,
variableOffset.textBoxScale,
rotateWithMap,
pitchWithMap,
state.getBearing());
} else {
// No offset -> this symbol hasn't been placed since coming on-screen
// No single box is particularly meaningful and all of them would be too noisy
// Use the center box just to show something's there, but mark it "not used"
used = false;
}
}
const auto& dynamicVertex = CollisionBoxProgram::dynamicVertex(placed, !used, shift);
bucket.textCollisionBox->dynamicVertices.extend(feature.boxes.size() * 4, dynamicVertex);
return shift;
};

auto updateCollisionCircles = [&](const auto& feature, const bool placed, bool isText) {
if (!feature.alongLine) {
Expand Down

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