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#include <llmr/text/placement.hpp>
#include <llmr/map/vector_tile.hpp>
#include <llmr/geometry/interpolate.hpp>
#include <llmr/style/bucket_description.hpp>
#include <llmr/renderer/text_bucket.hpp>
#include <llmr/util/math.hpp>
#include <llmr/util/constants.hpp>
using namespace llmr;
const int Placement::tileExtent = 4096;
const int Placement::glyphSize =
24; // size in pixels of this glyphs in the tile
const float Placement::minScale = 0.125; // underscale by 3 zoom levels
Placement::Placement(int8_t zoom)
: zoom(zoom),
zOffset(log(256.0 / util::tileSize) / log(2)),
// Calculate the maximum scale we can go down in our fake-3d rtree so that
// placement still makes sense. This is calculated so that the minimum
// placement zoom can be at most 25.5 (we use an unsigned integer x10 to
// store the minimum zoom).
//
// We don't want to place labels all the way to 25.5. This lets too many
// glyphs be placed, slowing down collision checking. Only place labels if
// they will show up within the intended zoom range of the tile.
// TODO make this not hardcoded to 3
maxPlacementScale(exp(log(2) * util::min((25.5 - zoom), 3.0))) {}
bool byScale(const Anchor &a, const Anchor &b) { return a.scale < b.scale; }
static const Glyph null_glyph;
inline const Glyph &getGlyph(const GlyphPlacement &placed,
const IndexedFaces &faces) {
if (placed.face < faces.size()) {
const GlyphPositions &face = *faces[placed.face];
if (&face) {
auto it = face.find(placed.glyph);
if (it != face.end()) {
return it->second;
} else {
fprintf(stderr, "glyph %d does not exist\n", placed.glyph);
}
} else {
fprintf(stderr, "face pointer is null\n");
}
} else {
fprintf(stderr, "face does not exist\n");
}
return null_glyph;
}
struct GlyphInstance {
explicit GlyphInstance(const vec2<float> &anchor) : anchor(anchor) {}
explicit GlyphInstance(const vec2<float> &anchor, float offset,
float minScale, float maxScale, float angle)
: anchor(anchor),
offset(offset),
minScale(minScale),
maxScale(maxScale),
angle(angle) {}
const vec2<float> anchor;
const float offset = 0.0f;
const float minScale = Placement::minScale;
const float maxScale = std::numeric_limits<float>::infinity();
const float angle = 0.0f;
};
typedef std::vector<GlyphInstance> GlyphInstances;
void getSegmentGlyphs(std::back_insert_iterator<GlyphInstances> glyphs,
Anchor &anchor, float offset,
const std::vector<Coordinate> &line, int segment,
int8_t direction, float maxAngleDelta) {
const bool upsideDown = direction < 0;
if (offset < 0)
direction *= -1;
if (direction > 0)
segment++;
vec2<float> newAnchor = anchor;
if (line.size() <= segment) {
return;
}
vec2<float> end = line[segment];
float prevscale = std::numeric_limits<float>::infinity();
float prevAngle = 0.0f;
offset = fabs(offset);
const float placementScale = anchor.scale;
while (true) {
const float dist = util::dist<float>(newAnchor, end);
const float scale = offset / dist;
float angle = -atan2(end.x - newAnchor.x, end.y - newAnchor.y) +
direction * M_PI / 2.0f;
if (upsideDown)
angle += M_PI;
// Don't place around sharp corners
float angleDiff = fmod((angle - prevAngle), (2.0f * M_PI));
if (prevAngle && angleDiff > maxAngleDelta) {
anchor.scale = prevscale;
break;
}
glyphs = GlyphInstance{
/* anchor */ newAnchor,
/* offset */ static_cast<float>(upsideDown ? M_PI : 0.0),
/* minScale */ scale,
/* maxScale */ prevscale,
/* angle */ static_cast<float>(
fmod((angle + 2.0 * M_PI), (2.0 * M_PI)))};
if (scale <= placementScale)
break;
newAnchor = end;
// skip duplicate nodes
while (newAnchor == end) {
segment += direction;
if (line.size() <= segment) {
anchor.scale = scale;
return;
}
end = line[segment];
}
vec2<float> normal = util::normal<float>(newAnchor, end) * dist;
newAnchor = newAnchor - normal;
prevscale = scale;
prevAngle = angle;
}
}
PlacedGlyphs getGlyphs(Anchor &anchor, float advance, const Shaping &shaping,
const IndexedFaces &faces, float fontScale,
bool horizontal, const std::vector<Coordinate> &line,
float maxAngleDelta, float rotate) {
// The total text advance is the width of this label.
// TODO: figure out correct ascender height.
vec2<float> origin{-advance / 2, -17};
// TODO: allow setting an alignment
// var alignment = 'center';
// if (alignment == 'center') {
// origin.x -= advance / 2;
// } else if (alignment == 'right') {
// origin.x -= advance;
// }
PlacedGlyphs glyphs;
const uint32_t buffer = 3;
for (const GlyphPlacement &placed : shaping) {
const Glyph &glyph = getGlyph(placed, faces);
if (!glyph) {
// This glyph is empty and doesn't have any pixels that we'd need to
// show.
continue;
}
uint32_t width = glyph.metrics.width;
uint32_t height = glyph.metrics.height;
width += buffer * 2;
height += buffer * 2;
// Increase to next number divisible by 4, but at least 1.
// This is so we can scale down the texture coordinates and pack them
// into 2 bytes rather than 4 bytes.
width += (4 - width % 4);
height += (4 - height % 4);
float x =
(origin.x + placed.x + glyph.metrics.left - buffer + width / 2) *
fontScale;
GlyphInstances glyphInstances;
if (anchor.segment >= 0) {
getSegmentGlyphs(std::back_inserter(glyphInstances), anchor, x,
line, anchor.segment, 1, maxAngleDelta);
getSegmentGlyphs(std::back_inserter(glyphInstances), anchor, x,
line, anchor.segment, -1, maxAngleDelta);
} else {
glyphInstances.emplace_back(GlyphInstance{anchor});
}
const float x1 = origin.x + placed.x + glyph.metrics.left - buffer;
const float y1 = origin.y + placed.y - glyph.metrics.top - buffer;
const float x2 = x1 + width;
const float y2 = y1 + height;
const vec2<float> otl{x1, y1};
const vec2<float> otr{x2, y1};
const vec2<float> obl{x1, y2};
const vec2<float> obr{x2, y2};
const CollisionRect obox{fontScale *x1, fontScale *y1,
fontScale *x2, fontScale *y2};
for (const GlyphInstance &instance : glyphInstances) {
vec2<float> tl = otl;
vec2<float> tr = otr;
vec2<float> bl = obl;
vec2<float> br = obr;
CollisionRect box = obox;
// Clamp to -90/+90 degrees
const float angle = instance.angle + rotate;
if (angle) {
// Compute the transformation matrix.
float angle_sin = sin(angle);
float angle_cos = cos(angle);
std::array<float, 4> matrix = {
{angle_cos, -angle_sin, angle_sin, angle_cos}};
tl = tl.matMul(matrix);
tr = tr.matMul(matrix);
bl = bl.matMul(matrix);
br = br.matMul(matrix);
// Calculate the rotated glyph's bounding box offsets from the
// anchor point.
box = CollisionRect{
fontScale * util::min(tl.x, tr.x, bl.x, br.x),
fontScale * util::min(tl.y, tr.y, bl.y, br.y),
fontScale * util::max(tl.x, tr.x, bl.x, br.x),
fontScale * util::max(tl.y, tr.y, bl.y, br.y)};
}
// Remember the glyph for later insertion.
glyphs.emplace_back(PlacedGlyph{
tl, tr, bl, br, glyph.rect, width, height,
static_cast<float>(
fmod((anchor.angle + rotate + instance.offset + 2 * M_PI),
(2 * M_PI))),
GlyphBox{box, instance.minScale, instance.maxScale,
instance.anchor, horizontal}});
}
}
// Prevent label from extending past the end of the line
for (PlacedGlyph &g : glyphs) {
g.glyphBox.minScale = util::max(g.glyphBox.minScale, anchor.scale);
}
return glyphs;
}
void Placement::addFeature(TextBucket& bucket,
const std::vector<Coordinate> &line,
const BucketGeometryDescription &info,
const IndexedFaces &faces,
const Shaping &shaping) {
const bool horizontal = info.path == TextPathType::Horizontal;
const float padding = info.padding;
const float maxAngleDelta = info.maxAngleDelta;
const float textMinDistance = info.textMinDistance;
const float rotate = info.rotate;
const float fontScale =
(tileExtent / util::tileSize) / (glyphSize / info.font_size);
const float advance = measureText(faces, shaping);
Anchors anchors;
// fprintf(stderr, "adding feature with advance %f\n", advance);
if (line.size() == 1) {
// Point labels
anchors = Anchors{{Anchor{
static_cast<float>(line[0].x), static_cast<float>(line[0].y),
0, minScale}}};
} else {
// Line labels
anchors = interpolate(line, textMinDistance, minScale);
// Sort anchors by segment so that we can start placement with
// the anchors that can be shown at the lowest zoom levels.
std::sort(anchors.begin(), anchors.end(), byScale);
}
for (Anchor anchor : anchors) {
PlacedGlyphs glyphs =
getGlyphs(anchor, advance, shaping, faces, fontScale, horizontal,
line, maxAngleDelta, rotate);
PlacementProperty place =
collision.place(glyphs, anchor, anchor.scale, maxPlacementScale,
padding, horizontal);
if (place.zoom >= 0.0f) {
bucket.addGlyphs(glyphs, place.zoom, place.rotationRange,
zoom - zOffset);
}
}
}
float Placement::measureText(const IndexedFaces &faces,
const Shaping &shaping) {
float advance = 0;
// TODO: advance is not calculated correctly. we should instead use the
// bounding box of the glyph placement.
for (const GlyphPlacement &shape : shaping) {
advance += getGlyph(shape, faces).metrics.advance;
}
return advance;
}
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