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Change region reader to a visitor pattern

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Not keeping the whole region in memory reduces the needed space
to less than 5MB (from about 140).
This commit is contained in:
Matthias Schiffer 2015-02-02 01:41:17 +01:00
parent 1e5e315816
commit 8c1629af42
3 changed files with 30 additions and 32 deletions
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33
src/MinedMap.cpp
View file

@ -40,7 +40,19 @@
using namespace MinedMap;
static void writePNG(const char *filename, const uint32_t data[World::Region::SIZE*World::Chunk::SIZE][World::Region::SIZE*World::Chunk::SIZE]) {
static const size_t DIM = World::Region::SIZE*World::Chunk::SIZE;
static void addChunk(uint32_t image[DIM][DIM], size_t X, size_t Z, const World::Chunk *chunk) {
World::Chunk::Blocks layer = chunk->getTopLayer();
for (size_t x = 0; x < World::Chunk::SIZE; x++) {
for (size_t z = 0; z < World::Chunk::SIZE; z++)
image[Z*World::Chunk::SIZE+z][X*World::Chunk::SIZE+x] = htonl(layer.blocks[x][z].getColor());
}
}
static void writePNG(const char *filename, const uint32_t data[DIM][DIM]) {
std::FILE *f = std::fopen(filename, "wb");
if (!f)
throw std::system_error(errno, std::generic_category(), "unable to open output file");
@ -82,24 +94,9 @@ int main(int argc, char *argv[]) {
return 1;
}
World::Region region(argv[1]);
uint32_t image[DIM][DIM] = {};
uint32_t image[World::Region::SIZE*World::Chunk::SIZE][World::Region::SIZE*World::Chunk::SIZE] = {};
for (size_t X = 0; X < World::Region::SIZE; X++) {
for (size_t Z = 0; Z < World::Region::SIZE; Z++) {
const World::Chunk *chunk = region(X, Z);
if (!chunk)
continue;
World::Chunk::Blocks layer = chunk->getTopLayer();
for (size_t x = 0; x < World::Chunk::SIZE; x++) {
for (size_t z = 0; z < World::Chunk::SIZE; z++)
image[Z*World::Chunk::SIZE+z][X*World::Chunk::SIZE+x] = htonl(layer.blocks[x][z].getColor());
}
}
}
World::Region::visitChunks(argv[1], [&image] (size_t X, size_t Z, const World::Chunk *chunk) { addChunk(image, X, Z, chunk); });
writePNG(argv[2], image);

13
src/World/Region.cpp
View file

@ -54,7 +54,7 @@ Region::ChunkMap Region::processHeader(const uint8_t header[4096]) {
return map;
}
Region::Region(const char *filename) {
void Region::visitChunks(const char *filename, ChunkVisitor visitor) {
std::ifstream file;
file.exceptions(std::ios::failbit | std::ios::badbit);
file.open(filename, std::ios::in | std::ios::binary);
@ -68,6 +68,8 @@ Region::Region(const char *filename) {
chunkMap = processHeader(header);
}
bool seen[SIZE][SIZE] = {};
size_t i = 1, c = 0;
while (!file.eof()) {
auto it = chunkMap.find(i);
@ -80,16 +82,19 @@ Region::Region(const char *filename) {
size_t x, z, len;
std::tie(x, z, len) = it->second;
if (chunks[x][z])
if (seen[x][z])
throw std::invalid_argument("duplicate chunk");
seen[x][z] = true;
c++;
uint8_t buffer[len * 4096];
file.read((char *)buffer, len * 4096);
chunks[x][z].reset(new Chunk(Buffer(buffer, len * 4096)));
Chunk chunk(Buffer(buffer, len * 4096));
visitor(x, z, &chunk);
i += len;
c++;
}
if (c != chunkMap.size())

16
src/World/Region.hpp
View file

@ -28,6 +28,7 @@
#include "Chunk.hpp"
#include <functional>
#include <memory>
#include <stdexcept>
#include <tuple>
@ -41,23 +42,18 @@ class Region {
public:
static const size_t SIZE = 32;
typedef std::function<void (size_t, size_t, const Chunk *)> ChunkVisitor;
Region() = delete;
private:
typedef std::tuple<size_t, size_t, size_t> ChunkDesc;
typedef std::unordered_map<size_t, ChunkDesc> ChunkMap;
std::unique_ptr<Chunk> chunks[SIZE][SIZE];
static ChunkMap processHeader(const uint8_t header[4096]);
public:
Region(const char *filename);
const Chunk * operator()(size_t x, size_t z) {
if (x >= SIZE || z >= SIZE)
throw std::range_error("Region(): bad coordinates");
return chunks[x][z].get();
}
static void visitChunks(const char *filename, ChunkVisitor visitor);
};
}