Make mapgen edges a vector too

src/mapgen/mapgen.cpp

@@ -1127,25 +1127,13 @@ void MapgenParams::writeParams(Settings *settings) const
 s32 MapgenParams::getSpawnRangeMax()
 {
 	auto [emin, emax] = get_mapgen_edges(mapgen_limit, chunksize);
-	return std::min(-emin, emax);
+	s32 min_xz = std::max(emin.X, emin.Z), max_xz = std::min(emax.X, emax.Z);
+	return std::min(-min_xz, max_xz);
 }
 
 
-std::pair<s16, s16> get_mapgen_edges(s16 mapgen_limit, v3s16 chunksize)
+std::pair<v3s16, v3s16> get_mapgen_edges(s16 mapgen_limit, v3s16 chunksize)
 {
-	// FIXME: this is no longer exact
-	const s16 cs = std::max(std::max(chunksize.X, chunksize.Y), chunksize.Z);
-
-	// Central chunk offset, in blocks
-	s16 ccoff_b = -cs / 2;
-	// Chunksize, in nodes
-	s32 csize_n = cs * MAP_BLOCKSIZE;
-	// Minp/maxp of central chunk, in nodes
-	s16 ccmin = ccoff_b * MAP_BLOCKSIZE;
-	s16 ccmax = ccmin + csize_n - 1;
-	// Fullminp/fullmaxp of central chunk, in nodes
-	s16 ccfmin = ccmin - MAP_BLOCKSIZE;
-	s16 ccfmax = ccmax + MAP_BLOCKSIZE;
 	// Effective mapgen limit, in blocks
 	// Uses same calculation as ServerMap::blockpos_over_mapgen_limit(v3s16 p)
 	s16 mapgen_limit_b = rangelim(mapgen_limit,
@@ -1153,10 +1141,29 @@ std::pair<s16, s16> get_mapgen_edges(s16 mapgen_limit, v3s16 chunksize)
 	// Effective mapgen limits, in nodes
 	s16 mapgen_limit_min = -mapgen_limit_b * MAP_BLOCKSIZE;
 	s16 mapgen_limit_max = (mapgen_limit_b + 1) * MAP_BLOCKSIZE - 1;
-	// Number of complete chunks from central chunk fullminp/fullmaxp
+
-	// to effective mapgen limits.
+	const auto &calculate = [&] (s16 cs) -> std::pair<s16, s16> {
-	s16 numcmin = std::max((ccfmin - mapgen_limit_min) / csize_n, 0);
+		// Central chunk offset, in blocks
-	s16 numcmax = std::max((mapgen_limit_max - ccfmax) / csize_n, 0);
+		s16 ccoff_b = -cs / 2;
+		// Chunksize, in nodes
+		s32 csize_n = cs * MAP_BLOCKSIZE;
+		// Minp/maxp of central chunk, in nodes
+		s16 ccmin = ccoff_b * MAP_BLOCKSIZE;
+		s16 ccmax = ccmin + csize_n - 1;
+		// Fullminp/fullmaxp of central chunk, in nodes
+		s16 ccfmin = ccmin - MAP_BLOCKSIZE;
+		s16 ccfmax = ccmax + MAP_BLOCKSIZE;
+		// Number of complete chunks from central chunk fullminp/fullmaxp
+		// to effective mapgen limits.
+		s16 numcmin = std::max((ccfmin - mapgen_limit_min) / csize_n, 0);
+		s16 numcmax = std::max((mapgen_limit_max - ccfmax) / csize_n, 0);
+		return {ccmin - numcmin * csize_n, ccmax + numcmax * csize_n};
+	};
+
 	// Mapgen edges, in nodes
-	return {ccmin - numcmin * csize_n, ccmax + numcmax * csize_n};
+	v3s16 emin, emax;
+	std::tie(emin.X, emax.X) = calculate(chunksize.X);
+	std::tie(emin.Y, emax.Y) = calculate(chunksize.Y);
+	std::tie(emin.Z, emax.Z) = calculate(chunksize.Z);
+	return {emin, emax};
 }

src/mapgen/mapgen.h

@@ -325,4 +325,4 @@ protected:
 
 // Calculate exact edges of the outermost mapchunks that are within the set
 // mapgen_limit. Returns the minimum and maximum edges in nodes in that order.
-std::pair<s16, s16> get_mapgen_edges(s16 mapgen_limit, v3s16 chunksize);
+std::pair<v3s16, v3s16> get_mapgen_edges(s16 mapgen_limit, v3s16 chunksize);

src/script/lua_api/l_mapgen.cpp

@@ -867,9 +867,9 @@ int ModApiMapgen::l_get_mapgen_edges(lua_State *L)
 		chunksize = params->chunksize;
 	}
 
-	std::pair<s16, s16> edges = get_mapgen_edges(mapgen_limit, chunksize);
+	auto edges = get_mapgen_edges(mapgen_limit, chunksize);
-	push_v3s16(L, v3s16(1, 1, 1) * edges.first);
+	push_v3s16(L, edges.first);
-	push_v3s16(L, v3s16(1, 1, 1) * edges.second);
+	push_v3s16(L, edges.second);
 	return 2;
 }
 

src/unittest/test_mapgen.cpp

@@ -7,6 +7,7 @@
 #include "emerge.h"
 #include "mapgen/mapgen.h"
 #include "mapgen/mg_biome.h"
+#include "irrlicht_changes/printing.h"
 #include "mock_server.h"
 
 class TestMapgen : public TestBase
@@ -18,6 +19,7 @@ public:
 	void runTests(IGameDef *gamedef);
 
 	void testBiomeGen(IGameDef *gamedef);
+	void testMapgenEdges();
 };
 
 static TestMapgen g_test_instance;
@@ -37,6 +39,7 @@ namespace {
 void TestMapgen::runTests(IGameDef *gamedef)
 {
 	TEST(testBiomeGen, gamedef);
+	TEST(testMapgenEdges);
 }
 
 void TestMapgen::testBiomeGen(IGameDef *gamedef)
@@ -98,7 +101,7 @@ void TestMapgen::testBiomeGen(IGameDef *gamedef)
 			{    0, "deciduous_forest_shore", S16_MIN },
 			{ -100, "deciduous_forest_shore", S16_MIN },
 		};
-		for (const auto expected : expected_biomes) {
+		for (const auto &expected : expected_biomes) {
 			Biome *biome = biomegen->getBiomeAtIndex(
 				(1 * CSIZE.X) + 1, // index in CSIZE 2D noise map
 				v3s16(2000, expected.check_y, -1000) // absolute coordinates
@@ -123,3 +126,15 @@ void TestMapgen::testBiomeGen(IGameDef *gamedef)
 	}
 }
 
+void TestMapgen::testMapgenEdges()
+{
+	v3s16 emin, emax;
+
+	std::tie(emin, emax) = get_mapgen_edges(31007, v3s16(5));
+	UASSERTEQ(auto, emin, v3s16(-30912));
+	UASSERTEQ(auto, emax, v3s16(30927));
+
+	std::tie(emin, emax) = get_mapgen_edges(502 * MAP_BLOCKSIZE, v3s16(1, 2, 1));
+	UASSERTEQ(auto, emin, v3s16(-8016));
+	UASSERTEQ(auto, emax, v3s16(8031, 8015, 8031));
+}