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Factor out and improve no-op drawing elimination

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This commit is contained in:
Eric Fischer 2014-09-24 11:42:20 -07:00
parent ef3d9867fc
commit fbf60b6d80
1 changed files with 64 additions and 11 deletions
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75
tile.cc
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@ -126,19 +126,21 @@ int draw(struct draw *geom, int n, mapnik::vector::tile_feature *feature) {
int dx = wwx - px;
int dy = wwy - py;
if (dx != 0 || dy != 0 || length == 0) {
if (feature != NULL) {
feature->add_geometry((dx << 1) ^ (dx >> 31));
feature->add_geometry((dy << 1) ^ (dy >> 31));
}
if (dx == 0 && dy == 0 && op == VT_LINETO) {
printf("0 delta\n");
}
px = wwx;
py = wwy;
length++;
if (feature != NULL) {
feature->add_geometry((dx << 1) ^ (dx >> 31));
feature->add_geometry((dy << 1) ^ (dy >> 31));
}
if (op == VT_LINETO && (dx != 0 || dy != 0)) {
drew = 1;
}
px = wwx;
py = wwy;
length++;
if (op == VT_LINETO && (dx != 0 || dy != 0)) {
drew = 1;
}
} else if (op == VT_CLOSEPATH) {
length++;
@ -154,6 +156,53 @@ int draw(struct draw *geom, int n, mapnik::vector::tile_feature *feature) {
return drew;
}
int remove_noop(struct draw *geom, int n) {
// first pass: remove empty linetos
long long x = 0, y = 0;
int out = 0;
int i;
for (i = 0; i < n; i++) {
if (geom[i].op == VT_LINETO && geom[i].x == x && geom[i].y == y) {
continue;
}
if (geom[i].op == VT_CLOSEPATH) {
geom[out++] = geom[i];
} else { /* moveto or lineto */
geom[out++] = geom[i];
x = geom[i].x;
y = geom[i].y;
}
}
// second pass: remove unused movetos
n = out;
out = 0;
for (i = 0; i < n; i++) {
if (geom[i].op == VT_MOVETO) {
if (i + 1 >= n) {
continue;
}
if (geom[i + 1].op == VT_MOVETO) {
continue;
}
if (geom[i + 1].op == VT_CLOSEPATH) {
i++; // also remove unused closepath
continue;
}
}
geom[out++] = geom[i];
}
return out;
}
void write_tile(struct index *start, struct index *end, char *metabase, unsigned *file_bbox, int z, unsigned tx, unsigned ty, int detail, int basezoom, struct pool *file_keys) {
GOOGLE_PROTOBUF_VERIFY_VERSION;
@ -215,6 +264,10 @@ void write_tile(struct index *start, struct index *end, char *metabase, unsigned
deserialize_int(&meta, &t);
decode_feature(&meta, geom, z, tx, ty, detail);
if (t == VT_LINE || t == VT_POLYGON) {
len = remove_noop(geom, len);
}
if (t == VT_POINT || draw(geom, len, NULL)) {
struct pool_val *pv = pool_long_long(&dup, &i->fpos, 0);
if (pv->n == 0) {