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Port scanline algorithm from _getCoveringTiles()

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fixes #22
This commit is contained in:
Konstantin Käfer
2014-03-04 14:50:17 +01:00
parent ed5e335da1
commit ba5070bf52
7 changed files with 133 additions and 32 deletions
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24
src/map/map.cpp
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@@ -3,6 +3,7 @@
#include <llmr/platform/platform.hpp>
#include <llmr/style/resources.hpp>
#include <llmr/style/sprite.hpp>
#include <llmr/map/coverage.hpp>
#include <algorithm>
@@ -329,27 +330,12 @@ bool Map::updateTiles() {
int32_t min_covering_zoom = zoom - 10;
if (min_covering_zoom < min_zoom) min_covering_zoom = min_zoom;
int32_t max_dim = pow(2, zoom);
// Map four viewport corners to pixel coordinates
box box;
transform.mapCornersToBox(zoom, box);
box box = transform.mapCornersToBox(zoom);
vec2<int32_t> tl, br;
tl.x = fmax(0, floor(fmin(box.tl.x, box.bl.x)));
tl.y = fmax(0, floor(fmin(box.tl.y, box.tr.y)));
br.x = fmin(max_dim, ceil(fmax(box.tr.x, box.br.x)));
br.y = fmin(max_dim, ceil(fmax(box.bl.y, box.br.y)));
// TODO: Discard tiles that are outside the viewport
std::forward_list<Tile::ID> required;
for (int32_t y = tl.y; y < br.y; ++y) {
for (int32_t x = tl.x; x < br.x; ++x) {
required.emplace_front(x, y, zoom);
}
}
// Performs a scanline algorithm search that covers the rectangle of the box
// and sorts them by proximity to the center.
std::forward_list<Tile::ID> required = llmr::covering_tiles(zoom, box);
// Retain is a list of tiles that we shouldn't delete, even if they are not
// the most ideal tile for the current viewport. This may include tiles like