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[core] add algorithm for computing masks for raster tiles

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This commit is contained in:
Konstantin Käfer
2017-07-05 15:38:50 +02:00
parent 541712aac7
commit 4dff51719b
9 changed files with 323 additions and 0 deletions
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38
benchmark/parse/tile_mask.benchmark.cpp Normal file
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@@ -0,0 +1,38 @@
#include <benchmark/benchmark.h>
#include <mbgl/algorithm/update_tile_masks.hpp>
using namespace mbgl;
class MaskedRenderable {
public:
MaskedRenderable(const UnwrappedTileID& id_, TileMask&& mask_)
: id(id_), mask(std::move(mask_)) {
}
UnwrappedTileID id;
TileMask mask;
bool used = true;
void setMask(TileMask&& mask_) {
mask = std::move(mask_);
}
};
static void TileMaskGeneration(benchmark::State& state) {
std::vector<MaskedRenderable> renderables = {
MaskedRenderable{ UnwrappedTileID{ 12, 1028, 1456 }, {} },
MaskedRenderable{ UnwrappedTileID{ 13, 2056, 2912 }, {} },
MaskedRenderable{ UnwrappedTileID{ 13, 2056, 2913 }, {} },
MaskedRenderable{ UnwrappedTileID{ 14, 4112, 5824 }, {} },
MaskedRenderable{ UnwrappedTileID{ 14, 4112, 5827 }, {} },
MaskedRenderable{ UnwrappedTileID{ 14, 4114, 5824 }, {} },
MaskedRenderable{ UnwrappedTileID{ 14, 4114, 5825 }, {} },
};
while (state.KeepRunning()) {
algorithm::updateTileMasks<MaskedRenderable>({ renderables.begin(), renderables.end() });
}
}
BENCHMARK(TileMaskGeneration);

1
cmake/benchmark-files.cmake
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@@ -10,6 +10,7 @@ set(MBGL_BENCHMARK_FILES
# parse
benchmark/parse/filter.benchmark.cpp
benchmark/parse/tile_mask.benchmark.cpp
benchmark/parse/vector_tile.benchmark.cpp
# src

1
cmake/benchmark.cmake
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@@ -19,6 +19,7 @@ target_link_libraries(mbgl-benchmark
PRIVATE mbgl-core
)
target_add_mason_package(mbgl-benchmark PRIVATE boost)
target_add_mason_package(mbgl-benchmark PRIVATE benchmark)
target_add_mason_package(mbgl-benchmark PRIVATE rapidjson)
target_add_mason_package(mbgl-benchmark PRIVATE protozero)

2
cmake/core-files.cmake
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@@ -15,6 +15,7 @@ set(MBGL_CORE_FILES
src/mbgl/algorithm/generate_clip_ids.hpp
src/mbgl/algorithm/generate_clip_ids_impl.hpp
src/mbgl/algorithm/update_renderables.hpp
src/mbgl/algorithm/update_tile_masks.hpp
# annotation
include/mbgl/annotation/annotation.hpp
@@ -205,6 +206,7 @@ set(MBGL_CORE_FILES
src/mbgl/renderer/renderer_observer.hpp
src/mbgl/renderer/style_diff.cpp
src/mbgl/renderer/style_diff.hpp
src/mbgl/renderer/tile_mask.hpp
src/mbgl/renderer/tile_parameters.hpp
src/mbgl/renderer/tile_pyramid.cpp
src/mbgl/renderer/tile_pyramid.hpp

1
cmake/test-files.cmake
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@@ -10,6 +10,7 @@ set(MBGL_TEST_FILES
test/algorithm/generate_clip_ids.test.cpp
test/algorithm/mock.hpp
test/algorithm/update_renderables.test.cpp
test/algorithm/update_tile_masks.test.cpp
# api
test/api/annotations.test.cpp

128
src/mbgl/algorithm/update_tile_masks.hpp Normal file
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@@ -0,0 +1,128 @@
#pragma once
#include <mbgl/renderer/tile_mask.hpp>
#include <vector>
#include <functional>
#include <algorithm>
namespace mbgl {
namespace algorithm {
namespace {
template <typename Renderable>
void computeTileMasks(
const CanonicalTileID& root,
const UnwrappedTileID ref,
typename std::vector<std::reference_wrapper<Renderable>>::const_iterator it,
const typename std::vector<std::reference_wrapper<Renderable>>::const_iterator end,
TileMask& mask) {
// If the reference or any of its children is found in the list, we need to recurse.
for (; it != end; ++it) {
auto& renderable = it->get();
if (!renderable.used) {
continue;
}
if (ref == renderable.id) {
// The current tile is masked out, so we don't need to add them to the mask set.
return;
} else if (renderable.id.isChildOf(ref)) {
// There's at least one child tile that is masked out, so recursively descend.
for (const auto& child : ref.children()) {
computeTileMasks<Renderable>(root, child, it, end, mask);
}
return;
}
}
// We couldn't find a child, so it's definitely a masked part.
// Compute the difference between the root tile ID and the reference tile ID, since TileMask
// elements are always relative (see below for explanation).
const uint8_t diffZ = ref.canonical.z - root.z;
mask.emplace(diffZ, ref.canonical.x - (root.x << diffZ), ref.canonical.y - (root.y << diffZ));
}
} // namespace
// Updates the TileMasks for all renderables. Renderables are objects that have an UnwrappedTileID
// property indicating where they should be rendered on the screen. A TileMask describes all regions
// within that tile that are *not* covered by other Renderables.
// Example: Renderables in our list are 2/1/3, 3/3/6, and 4/5/13. The schematic for creating the
// TileMask for 2/1/3 looks like this:
//
// ┌────────┬────────┬─────────────────┐
// │ │ │#################│
// │ 4/4/12 │ 4/5/12 │#################│
// │ │ │#################│
// ├──────3/2/6──────┤#####3/3/6#######│
// │ │########│#################│
// │ 4/4/13 │#4/5/13#│#################│
// │ │########│#################│
// ├────────┴──────2/1/3───────────────┤
// │ │ │
// │ │ │
// │ │ │
// │ 3/2/7 │ 3/3/7 │
// │ │ │
// │ │ │
// │ │ │
// └─────────────────┴─────────────────┘
//
// The TileMask for 2/1/3 thus consists of the tiles 4/4/12, 4/5/12, 4/4/13, 3/2/7, and 3/3/7,
// but it does *not* include 4/5/13, and 3/3/6, since these are other Renderables.
// A TileMask always contains TileIDs *relative* to the tile it is generated for, so 2/1/3 is
// "subtracted" from these TileIDs. The final TileMask for 2/1/3 will thus be:
//
// ┌────────┬────────┬─────────────────┐
// │ │ │#################│
// │ 2/0/0 │ 2/1/0 │#################│
// │ │ │#################│
// ├────────┼────────┤#################│
// │ │########│#################│
// │ 2/0/1 │########│#################│
// │ │########│#################│
// ├────────┴────────┼─────────────────┤
// │ │ │
// │ │ │
// │ │ │
// │ 1/0/1 │ 1/1/1 │
// │ │ │
// │ │ │
// │ │ │
// └─────────────────┴─────────────────┘
//
// Only other Renderables that are *children* of the Renderable we are generating the mask for will
// be considered. For example, adding a Renderable with TileID 4/8/13 won't affect the TileMask for
// 2/1/3, since it is not a descendant of it.
template <typename Renderable>
void updateTileMasks(std::vector<std::reference_wrapper<Renderable>> renderables) {
std::sort(renderables.begin(), renderables.end(),
[](const Renderable& a, const Renderable& b) { return a.id < b.id; });
TileMask mask;
const auto end = renderables.end();
for (auto it = renderables.begin(); it != end; it++) {
auto& renderable = it->get();
if (!renderable.used) {
continue;
}
// Try to add all remaining ids as children. We sorted the tile list
// by z earlier, so all preceding items cannot be children of the current
// tile. We also compute the lower bound of the next wrap, because items of the next wrap
// can never be children of the current wrap.
auto child_it = std::next(it);
const auto children_end = std::lower_bound(
child_it, end,
UnwrappedTileID{ static_cast<int16_t>(renderable.id.wrap + 1), { 0, 0, 0 } },
[](auto& a, auto& b) { return a.get().id < b; });
mask.clear();
computeTileMasks<Renderable>(renderable.id.canonical, renderable.id, child_it, children_end,
mask);
renderable.setMask(std::move(mask));
}
}
} // namespace algorithm
} // namespace mbgl

15
src/mbgl/renderer/tile_mask.hpp Normal file
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@@ -0,0 +1,15 @@
#pragma once
#include <mbgl/tile/tile_id.hpp>
#include <set>
namespace mbgl {
// A TileMask is a set of TileIDs that describe what part of a tile should be rendered. It omits
// those parts of the tile that are covered by other/better tiles. If the entire tile should be
// rendered, it contains the { 0, 0, 0 } tile. If it's empty, no part of the tile will be rendered.
// TileMasks are typically generated with algorithm::updateTileMasks().
using TileMask = std::set<CanonicalTileID>;
} // namespace mbgl

5
src/mbgl/tile/tile_id_io.cpp
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@@ -6,6 +6,8 @@
namespace mbgl {
::std::ostream& operator<<(::std::ostream& os, const CanonicalTileID& rhs) {
// Uncomment this to create code instead of shorthands.
// return os << "CanonicalTileID{ " << uint32_t(rhs.z) << ", " << rhs.x << ", " << rhs.y << " }";
return os << uint32_t(rhs.z) << "/" << rhs.x << "/" << rhs.y;
}
@@ -26,6 +28,9 @@ std::string toString(const OverscaledTileID& rhs) {
} // namespace util
::std::ostream& operator<<(::std::ostream& os, const UnwrappedTileID& rhs) {
// Uncomment this to create code instead of shorthands.
// return os << "UnwrappedTileID{ " << uint32_t(rhs.wrap) << ", { " << uint32_t(rhs.canonical.z)
// << ", " << rhs.canonical.x << ", " << rhs.canonical.y << " } }";
return os << rhs.canonical << (rhs.wrap >= 0 ? "+" : "") << rhs.wrap;
}

132
test/algorithm/update_tile_masks.test.cpp Normal file
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@@ -0,0 +1,132 @@
#include <mbgl/test/util.hpp>
#include <mbgl/algorithm/update_tile_masks.hpp>
using namespace mbgl;
namespace {
class MaskedRenderable {
public:
MaskedRenderable(const UnwrappedTileID& id_, TileMask&& mask_)
: id(id_), mask(std::move(mask_)) {
}
UnwrappedTileID id;
TileMask mask;
bool used = true;
void setMask(TileMask&& mask_) {
mask = std::move(mask_);
}
};
bool operator==(const MaskedRenderable& lhs, const MaskedRenderable& rhs) {
return lhs.id == rhs.id && lhs.mask == rhs.mask;
}
::std::ostream& operator<<(::std::ostream& os, const MaskedRenderable& rhs) {
os << "MaskedRenderable{ " << rhs.id << ", { ";
bool first = true;
for (auto& id : rhs.mask) {
if (!first) {
os << ", ";
} else {
first = false;
}
os << id;
}
return os << " } }";
}
} // namespace
void validate(const std::vector<MaskedRenderable> expected) {
std::vector<MaskedRenderable> actual = expected;
std::for_each(actual.begin(), actual.end(),
[](auto& renderable) { renderable.mask.clear(); });
algorithm::updateTileMasks<MaskedRenderable>({ actual.begin(), actual.end() });
EXPECT_EQ(expected, actual);
}
TEST(UpdateTileMasks, NoChildren) {
validate({
MaskedRenderable{ UnwrappedTileID{ 0, 0, 0 }, { CanonicalTileID{ 0, 0, 0 } } },
});
validate({
MaskedRenderable{ UnwrappedTileID{ 4, 3, 8 }, { CanonicalTileID{ 0, 0, 0 } } },
});
validate({
MaskedRenderable{ UnwrappedTileID{ 1, 0, 0 }, { CanonicalTileID{ 0, 0, 0 } } },
MaskedRenderable{ UnwrappedTileID{ 1, 1, 1 }, { CanonicalTileID{ 0, 0, 0 } } },
});
validate({
MaskedRenderable{ UnwrappedTileID{ 1, 0, 0 }, { CanonicalTileID{ 0, 0, 0 } } },
MaskedRenderable{ UnwrappedTileID{ 2, 2, 3 }, { CanonicalTileID{ 0, 0, 0 } } },
});
}
TEST(UpdateTileMasks, ParentAndFourChildren) {
validate({
// Mask is empty (== not rendered!) because we have four covering children.
MaskedRenderable{ UnwrappedTileID{ 0, 0, 0 }, {} },
// All four covering children
MaskedRenderable{ UnwrappedTileID{ 1, 0, 0 }, { CanonicalTileID{ 0, 0, 0 } } },
MaskedRenderable{ UnwrappedTileID{ 1, 0, 1 }, { CanonicalTileID{ 0, 0, 0 } } },
MaskedRenderable{ UnwrappedTileID{ 1, 1, 0 }, { CanonicalTileID{ 0, 0, 0 } } },
MaskedRenderable{ UnwrappedTileID{ 1, 1, 1 }, { CanonicalTileID{ 0, 0, 0 } } },
});
}
TEST(UpdateTileMasks, OneChild) {
validate({
MaskedRenderable{ UnwrappedTileID{ 0, 0, 0 },
// Only render the three children that aren't covering the other tile.
{ CanonicalTileID{ 1, 0, 1 }, CanonicalTileID{ 1, 1, 0 },
CanonicalTileID{ 1, 1, 1 } } },
MaskedRenderable{ UnwrappedTileID{ 1, 0, 0 }, { CanonicalTileID{ 0, 0, 0 } } },
});
}
TEST(UpdateTileMasks, Complex) {
validate({
MaskedRenderable{ UnwrappedTileID{ 0, 0, 0 },
{ CanonicalTileID{ 1, 0, 1 }, CanonicalTileID{ 1, 1, 0 },
CanonicalTileID{ 2, 2, 3 }, CanonicalTileID{ 2, 3, 2 },
CanonicalTileID{ 3, 6, 7 }, CanonicalTileID{ 3, 7, 6 } } },
MaskedRenderable{ UnwrappedTileID{ 0, { 1, 0, 0 } }, { CanonicalTileID{ 0, 0, 0 } } },
MaskedRenderable{ UnwrappedTileID{ 0, { 2, 2, 2 } }, { CanonicalTileID{ 0, 0, 0 } } },
MaskedRenderable{ UnwrappedTileID{ 0, { 3, 7, 7 } }, { CanonicalTileID{ 0, 0, 0 } } },
MaskedRenderable{ UnwrappedTileID{ 0, { 3, 6, 6 } }, { CanonicalTileID{ 0, 0, 0 } } },
});
validate({
MaskedRenderable{ UnwrappedTileID{ 0, 0, 0 },
{ CanonicalTileID{ 1, 0, 1 }, CanonicalTileID{ 1, 1, 0 },
CanonicalTileID{ 1, 1, 1 }, CanonicalTileID{ 2, 0, 0 },
CanonicalTileID{ 2, 0, 1 }, CanonicalTileID{ 2, 1, 0 },
CanonicalTileID{ 3, 2, 3 }, CanonicalTileID{ 3, 3, 2 },
CanonicalTileID{ 3, 3, 3 }, CanonicalTileID{ 4, 4, 5 },
CanonicalTileID{ 4, 5, 4 }, CanonicalTileID{ 4, 5, 5 } } },
MaskedRenderable{ UnwrappedTileID{ 4, 4, 4 }, { CanonicalTileID{ 0, 0, 0 } } },
});
validate({
MaskedRenderable{ UnwrappedTileID{ 12, 1028, 1456 },
{ CanonicalTileID{ 1, 1, 1 }, CanonicalTileID{ 2, 3, 0 },
CanonicalTileID{ 2, 3, 1 } } },
MaskedRenderable{ UnwrappedTileID{ 13, 2056, 2912 },
{ CanonicalTileID{ 1, 0, 1 }, CanonicalTileID{ 1, 1, 0 },
CanonicalTileID{ 1, 1, 1 } } },
MaskedRenderable{ UnwrappedTileID{ 13, 2056, 2913 },
{ CanonicalTileID{ 1, 0, 0 }, CanonicalTileID{ 1, 1, 0 },
CanonicalTileID{ 1, 1, 1 } } },
MaskedRenderable{ UnwrappedTileID{ 14, 4112, 5824 }, { CanonicalTileID{ 0, 0, 0 } } },
MaskedRenderable{ UnwrappedTileID{ 14, 4112, 5827 }, { CanonicalTileID{ 0, 0, 0 } } },
MaskedRenderable{ UnwrappedTileID{ 14, 4114, 5824 }, { CanonicalTileID{ 0, 0, 0 } } },
MaskedRenderable{ UnwrappedTileID{ 14, 4114, 5825 }, { CanonicalTileID{ 0, 0, 0 } } },
});
}