diegoripley/tippecanoe
1
0
Fork 0
mirror of https://github.com/felt/tippecanoe.git synced 2026-10-02 08:25:40 +02:00
Code Issues Packages Projects Releases Wiki Activity

Generate fewer duplicate label points at high zoom levels (#42)

Browse Source
This commit is contained in:
Erica Fischer
2022-12-02 11:02:33 -08:00
committed by GitHub
parent 5c647cdb83
commit f1df09f147
6 changed files with 124 additions and 51 deletions
Download Patch File Download Diff File Expand all files Collapse all files
geometry.cpp
+42 -37
View File
@@ -1612,13 +1612,7 @@ drawvec polygon_to_anchor(const drawvec &geom) {
return drawvec();
}
static double dist(long long x1, long long y1, long long x2, long long y2) {
double dx = x2 - x1;
double dy = y2 - y1;
return sqrt(dx * dx + dy * dy);
}
drawvec spiral_anchors(drawvec const &geom, int tx, int ty, int z, unsigned long long label_point) {
drawvec checkerboard_anchors(drawvec const &geom, int tx, int ty, int z, unsigned long long label_point) {
drawvec out;
// anchor point in world coordinates
@@ -1628,48 +1622,59 @@ drawvec spiral_anchors(drawvec const &geom, int tx, int ty, int z, unsigned long
// upper left of tile in world coordinates
long long tx1 = 0, ty1 = 0;
// lower right of tile in world coordinates;
long long tx2 = 1LL << 32, ty2 = 1LL << 32;
long long tx2 = 1LL << 32; // , ty2 = 1LL << 32;
if (z != 0) {
tx1 = (long long) tx << (32 - z);
ty1 = (long long) ty << (32 - z);
tx2 = (long long) (tx + 1) << (32 - z);
ty2 = (long long) (ty + 1) << (32 - z);
// ty2 = (long long) (ty + 1) << (32 - z);
}
// min and max distance of corners of this tile from the label point
double min_radius, max_radius;
if (wx >= tx1 && wx <= tx2 && wy >= ty1 && wy <= ty2) {
// center is in this tile,
// so min is 0, max can't be more than sqrt(2) tiles
min_radius = 0;
max_radius = sqrt(2);
} else {
// center is elsewhere,
// so min is at most sqrt(2)/2 tiles short of the center of the tile
// and max is at most sqrt(2)/2 tiles past the center of the tile
min_radius = std::max(0.0, dist(wx, wy, (tx1 + tx2) / 2, (ty1 + ty2) / 2) / (1LL << (32 - z)) - sqrt(2) / 2);
max_radius = min_radius + sqrt(2);
// upper left of feature in world coordinates
long long bx1 = LLONG_MAX, by1 = LLONG_MAX;
// lower right of feature in world coordinates;
long long bx2 = LLONG_MIN, by2 = LLONG_MIN;
for (auto const &g : geom) {
bx1 = std::min(bx1, g.x + tx1);
by1 = std::min(by1, g.y + ty1);
bx2 = std::max(bx2, g.x + tx1);
by2 = std::max(by2, g.y + ty1);
}
// labels complete a circle every 0.4 tiles of radius
const double spiral_dist = 0.4;
if (bx1 > bx2 || by1 > by2) {
return out;
}
size_t min_i = pow(min_radius / spiral_dist, 2);
size_t max_i = pow(max_radius / spiral_dist, 2);
// labels repeat every 0.3 tiles at z0
double spiral_dist = 0.3;
if (z > 0) {
// only every ~6 tiles by the time we get to z15
spiral_dist = spiral_dist * exp(log(z) * 1.2);
}
// https://craftofcoding.wordpress.com/tag/sunflower-spiral/
double angle = M_PI * (3.0 - sqrt(5.0)); // 137.5 in radians
const long long label_spacing = spiral_dist * (tx2 - tx1);
for (size_t i = min_i; i <= max_i; i++) {
double r = sqrt(i) * spiral_dist;
double theta = i * angle;
// Convert polar to cartesian
long long x = r * cos(theta) * (1LL << (32 - z)) + wx;
long long y = r * sin(theta) * (1LL << (32 - z)) + wy;
long long x1 = floor(std::min(bx1 - wx, bx2 - wx) / label_spacing);
long long x2 = ceil(std::max(bx1 - wx, bx2 - wx) / label_spacing);
if (x >= tx1 && x <= tx2 && y >= ty1 && y <= ty2) {
// is it actually inside the bounding box of the feature? then keep it.
long long y1 = floor(std::min(by1 - wy, by2 - wy) / label_spacing - 0.5);
long long y2 = ceil(std::max(by1 - wy, by2 - wy) / label_spacing);
for (long long lx = x1; lx <= x2; lx++) {
for (long long ly = y1; ly <= y2; ly++) {
long long x = lx * label_spacing + wx;
long long y = ly * label_spacing + wy;
if (((unsigned long long) lx & 1) == 1) {
y += label_spacing / 2;
}
if (x < bx1 || x > bx2 || y < by1 || y > by2) {
continue;
}
for (size_t a = 0; a < geom.size(); a++) {
if (geom[a].op == VT_MOVETO) {
@@ -1683,7 +1688,7 @@ drawvec spiral_anchors(drawvec const &geom, int tx, int ty, int z, unsigned long
// If it's the central label, it's the best we've got,
// so accept it in any case. If it's from the outer spiral,
// don't use it if it's too close to a border.
if (i == 0) {
if (lx == 0 && ly == 0) {
out.push_back(draw(VT_MOVETO, x - tx1, y - ty1));
break;
} else {