Add --dumpblock flag for advanced use

This is not only useful for debugging minetestmapper itself but
also makes it a standalone tool for extracting data you want to work on
from a Minetest map.

TileGenerator.cpp

@@ -254,6 +254,11 @@ void TileGenerator::setExhaustiveSearch(int mode)
 	m_exhaustiveSearch = mode;
 }
 
+void TileGenerator::setDontWriteEmpty(bool f)
+{
+	m_dontWriteEmpty = f;
+}
+
 void TileGenerator::parseColorsFile(const std::string &fileName)
 {
 	std::ifstream in(fileName);
@@ -265,9 +270,8 @@ void TileGenerator::parseColorsFile(const std::string &fileName)
 void TileGenerator::printGeometry(const std::string &input)
 {
 	std::string input_path = input;
-	if (input_path[input.length() - 1] != PATH_SEPARATOR) {
+	if (input_path.back() != PATH_SEPARATOR)
 		input_path += PATH_SEPARATOR;
-	}
 
 	setExhaustiveSearch(EXH_NEVER);
 	openDb(input_path);
@@ -283,17 +287,33 @@ void TileGenerator::printGeometry(const std::string &input)
 
 }
 
-void TileGenerator::setDontWriteEmpty(bool f)
+void TileGenerator::dumpBlock(const std::string &input, BlockPos pos)
 {
-	m_dontWriteEmpty = f;
+	std::string input_path = input;
+	if (input_path.back() != PATH_SEPARATOR)
+		input_path += PATH_SEPARATOR;
+
+	openDb(input_path);
+
+	BlockList list;
+	std::vector<BlockPos> positions;
+	positions.emplace_back(pos);
+	m_db->getBlocksByPos(list, positions);
+	if (!list.empty()) {
+		const ustring &data = list.begin()->second;
+		for (u8 c : data)
+			printf("%02x", static_cast<int>(c));
+		printf("\n");
+	}
+
+	closeDatabase();
 }
 
 void TileGenerator::generate(const std::string &input, const std::string &output)
 {
 	std::string input_path = input;
-	if (input_path[input.length() - 1] != PATH_SEPARATOR) {
+	if (input_path.back() != PATH_SEPARATOR)
 		input_path += PATH_SEPARATOR;
-	}
 
 	if (m_dontWriteEmpty) // FIXME: possible too, just needs to be done differently
 		setExhaustiveSearch(EXH_NEVER);

include/TileGenerator.h

@@ -92,6 +92,8 @@ public:
 
 	void generate(const std::string &input, const std::string &output);
 	void printGeometry(const std::string &input);
+	void dumpBlock(const std::string &input, BlockPos pos);
+
 	static std::set<std::string> getSupportedBackends();
 
 private:

include/db.h

@@ -13,6 +13,7 @@ struct BlockPos {
 	int16_t z;
 
 	BlockPos() : x(0), y(0), z(0) {}
+	explicit BlockPos(int16_t v) : x(v), y(v), z(v) {}
 	BlockPos(int16_t x, int16_t y, int16_t z) : x(x), y(y), z(z) {}
 
 	// Implements the inverse ordering so that (2,2,2) < (1,1,1)

mapper.cpp

@@ -35,6 +35,7 @@ static void usage()
 		{"--colors", "<colors.txt>"},
 		{"--scales", "[t][b][l][r]"},
 		{"--exhaustive", "never|y|full|auto"},
+		{"--dumpblock", "x,y,z"},
 	};
 	const char *top_text =
 		"minetestmapper -i <world_path> -o <output_image.png> [options]\n"
@@ -110,15 +111,17 @@ int main(int argc, char *argv[])
 		{"scales", required_argument, 0, 'f'},
 		{"noemptyimage", no_argument, 0, 'n'},
 		{"exhaustive", required_argument, 0, 'j'},
+		{"dumpblock", required_argument, 0, 'k'},
 		{0, 0, 0, 0}
 	};
 
 	std::string input;
 	std::string output;
-	std::string colors = "";
+	std::string colors;
+	bool onlyPrintExtent = false;
+	BlockPos dumpblock(INT16_MIN);
 
 	TileGenerator generator;
-	bool onlyPrintExtent = false;
 	while (1) {
 		int option_index;
 		int c = getopt_long(argc, argv, "hi:o:", long_options, &option_index);
@@ -129,7 +132,6 @@ int main(int argc, char *argv[])
 			case 'h':
 				usage();
 				return 0;
-				break;
 			case 'i':
 				input = optarg;
 				break;
@@ -234,12 +236,23 @@ int main(int argc, char *argv[])
 					generator.setExhaustiveSearch(mode);
 				}
 				break;
+			case 'k': {
+				std::istringstream iss(optarg);
+				char c, c2;
+				iss >> dumpblock.x >> c >> dumpblock.y >> c2 >> dumpblock.z;
+				if (iss.fail() || c != ',' || c2 != ',') {
+					usage();
+					exit(1);
+				}
+				break;
+			}
 			default:
 				exit(1);
 		}
 	}
 
-	if (input.empty() || (!onlyPrintExtent && output.empty())) {
+	const bool need_output = !onlyPrintExtent && dumpblock.x == INT16_MIN;
+	if (input.empty() || (need_output && output.empty())) {
 		usage();
 		return 0;
 	}
@@ -249,6 +262,9 @@ int main(int argc, char *argv[])
 		if (onlyPrintExtent) {
 			generator.printGeometry(input);
 			return 0;
+		} else if (dumpblock.x != INT16_MIN) {
+			generator.dumpBlock(input, dumpblock);
+			return 0;
 		}
 
 		if(colors == "")
@@ -256,7 +272,7 @@ int main(int argc, char *argv[])
 		generator.parseColorsFile(colors);
 		generator.generate(input, output);
 
-	} catch (const std::runtime_error &e) {
+	} catch (const std::exception &e) {
 		std::cerr << "Exception: " << e.what() << std::endl;
 		return 1;
 	}

minetestmapper.6

@@ -77,7 +77,7 @@ Use specific map backend; supported: \fIsqlite3\fP, \fIleveldb\fP, \fIredis\fP,
 Limit area to specific geometry (\fIx:y+w+h\fP where x and y specify the lower left corner), e.g. "--geometry -800:-800+1600+1600"
 
 .TP
-.BR \-\-extent " " \fIextent\fR
+.BR \-\-extent
 Don't render the image, just print the extent of the map that would be generated, in the same format as the geometry above.
 
 .TP
@@ -93,7 +93,7 @@ Forcefully set path to colors.txt file (it's autodetected otherwise), e.g. "--co
 Draw scales on specified image edges (letters \fIt b l r\fP meaning top, bottom, left and right), e.g. "--scales tbr"
 
 .TP
-.BR \-\-exhaustive " \fImode\fR
+.BR \-\-exhaustive " " \fImode\fR
 Select if database should be traversed exhaustively or using range queries, available: \fInever\fP, \fIy\fP, \fIfull\fP, \fIauto\fP
 
 Defaults to \fIauto\fP. You shouldn't need to change this, but doing so can improve rendering times on large maps.
@@ -103,6 +103,10 @@ and
 .B max-y
 when you don't care about the world below e.g. -60 and above 1000 nodes.
 
+.TP
+.BR \-\-dumpblock " " \fIpos\fR
+Instead of rendering anything try to load the block at the given position (\fIx,y,z\fR) and print its raw data as hexadecimal.
+
 .SH MORE INFORMATION
 Website: https://github.com/minetest/minetestmapper