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Merge pull request #26 from mapbox/gammafix

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Clean up the gamma semantics a little.
This commit is contained in:
Eric Fischer 2015-03-23 14:47:17 -07:00
commit 3d074653b5
3 changed files with 29 additions and 27 deletions
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2
README.md
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@ -58,7 +58,7 @@ Options
* -f: Delete the mbtiles file if it already exists instead of giving an error
* -r <i>rate</i>: Rate at which dots are dropped at lower zoom levels (default 2.5)
* -b <i>pixels</i>: Buffer size where features are duplicated from adjacent tiles (default 5)
* -g <i>gamma</i>: Rate at which especially dense dots are dropped (default 1, for no effect). A gamma of 2 reduces the number of dots less than a pixel apart to the square root of their original number.
* -g <i>gamma</i>: Rate at which especially dense dots are dropped (default 0, for no effect). A gamma of 2 reduces the number of dots less than a pixel apart to the square root of their original number.
Example
-------

2
geojson.c
View File

@ -901,7 +901,7 @@ int main(int argc, char **argv) {
int minzoom = 0;
int force = 0;
double droprate = 2.5;
double gamma = 1;
double gamma = 0;
int buffer = 5;
const char *tmpdir = "/tmp";

6
tile.cc
View File

@ -489,11 +489,11 @@ long long write_tile(char **geoms, char *metabase, unsigned *file_bbox, int z, u
continue;
}
if (t == VT_POINT && z < feature_minzoom && gamma == 0) {
if (t == VT_POINT && z < feature_minzoom && gamma < 0) {
continue;
}
if (t == VT_POINT && gamma != 0) {
if (t == VT_POINT && gamma >= 0) {
seq++;
if (seq >= 0) {
seq -= interval;
@ -501,6 +501,7 @@ long long write_tile(char **geoms, char *metabase, unsigned *file_bbox, int z, u
continue;
}
if (gamma > 0) {
unsigned long long index = encode(bbox[0] / 2 + bbox[2] / 2, bbox[1] / 2 + bbox[3] / 2);
if (gap > 0) {
if (index == previndex) {
@ -528,6 +529,7 @@ long long write_tile(char **geoms, char *metabase, unsigned *file_bbox, int z, u
previndex = index;
}
}
bool reduced = false;
if (t == VT_POLYGON) {