Eliminate ALL cascading worldgen lag, with the following changes:

- Offset structures by minus half their width in x/z (as well as the usual +8), so they can't ever spill out of the 2x2 chunk area being generated (provided they are less than 16 blocks wide, which mine are)
- Pass the block placement flags 16 | 2 to Template#addBlocksToWorld instead of just 2, to prevent neighbour updates
- Ignore unloaded blocks when removing floating trees (in theory there can't be trees there anyway)

src/main/java/electroblob/wizardry/worldgen/WorldGenCrystalOre.java

@@ -15,8 +15,6 @@ import java.util.Random;
 
 public class WorldGenCrystalOre implements IWorldGenerator {
 
-	// TODO: Probably this and the flowers are causing cascading lag!
-
 	@Override
 	public void generate(Random random, int chunkX, int chunkZ, World world, IChunkGenerator chunkGenerator, IChunkProvider chunkProvider){
 

src/main/java/electroblob/wizardry/worldgen/WorldGenLibraryRuins.java

@@ -41,7 +41,8 @@ public class WorldGenLibraryRuins extends WorldGenSurfaceStructure {
 	@Override
 	public boolean canGenerate(Random random, World world, int chunkX, int chunkZ){
 		return ArrayUtils.contains(Wizardry.settings.libraryDimensions, world.provider.getDimension())
-				&& BiomeDictionary.getTypes(world.getBiome(new BlockPos(chunkX * 16 + 8, 0, chunkZ * 16 + 8)))
+				// +8 for the anti-cascading offset, and +8 for the middle of the generated area makes +16 in total
+				&& BiomeDictionary.getTypes(world.getBiome(new BlockPos(chunkX * 16 + 16, 0, chunkZ * 16 + 16)))
 				.stream().anyMatch(BIOME_TYPES::contains)
 				&& Wizardry.settings.libraryRarity > 0 && random.nextInt(Wizardry.settings.libraryRarity) == 0;
 	}
@@ -91,7 +92,7 @@ public class WorldGenLibraryRuins extends WorldGenSurfaceStructure {
 				}
 		);
 
-		template.addBlocksToWorld(world, origin, processor, settings, 2);
+		template.addBlocksToWorld(world, origin, processor, settings, 2 | 16);
 
 		WizardryAntiqueAtlasIntegration.markLibrary(world, origin.getX(), origin.getZ());
 	}

src/main/java/electroblob/wizardry/worldgen/WorldGenObelisk.java

@@ -62,7 +62,7 @@ public class WorldGenObelisk extends WorldGenSurfaceStructure {
 		ITemplateProcessor processor = (w, p, i) -> i.blockState.getBlock() instanceof BlockRunestone ? new Template.BlockInfo(
 				i.pos, i.blockState.withProperty(BlockRunestone.ELEMENT, element), i.tileentityData) : i;
 
-		template.addBlocksToWorld(world, origin, processor, settings, 2);
+		template.addBlocksToWorld(world, origin, processor, settings, 2 | 16);
 
 		WizardryAntiqueAtlasIntegration.markObelisk(world, origin.getX(), origin.getZ());
 

src/main/java/electroblob/wizardry/worldgen/WorldGenShrine.java

@@ -54,7 +54,7 @@ public class WorldGenShrine extends WorldGenSurfaceStructure {
 		ITemplateProcessor processor = (w, p, i) -> i.blockState.getBlock() instanceof BlockRunestone ? new Template.BlockInfo(
 				i.pos, i.blockState.withProperty(BlockRunestone.ELEMENT, element), i.tileentityData) : i;
 
-		template.addBlocksToWorld(world, origin, processor, settings, 2);
+		template.addBlocksToWorld(world, origin, processor, settings, 2 | 16);
 
 		WizardryAntiqueAtlasIntegration.markShrine(world, origin.getX(), origin.getZ());
 

src/main/java/electroblob/wizardry/worldgen/WorldGenSurfaceStructure.java

@@ -45,12 +45,12 @@ public abstract class WorldGenSurfaceStructure extends WorldGenWizardryStructure
 	protected BlockPos attemptPosition(Template template, PlacementSettings settings, Random random, World world,
 									   int chunkX, int chunkZ, String structureFile){
 
-		// Offset by (8, 8) to minimise cascading worldgen lag
+		BlockPos size = template.transformedSize(settings.getRotation());
+
+		// Offset by (8, 8) to minimise cascading worldgen lag, MINUS half the width of the structure (important!)
 		// See https://www.reddit.com/r/feedthebeast/cowmments/5x0twz/investigating_extreme_worldgen_lag/?ref=share&ref_source=embed&utm_content=title&utm_medium=post_embed&utm_name=c07cbb545f74487793783012794733d8&utm_source=embedly&utm_term=5x0twz
 		// Multiplying and left-shifting are identical but it's good practice to bitshift here I guess
-		BlockPos origin = new BlockPos(8 + (chunkX << 4) + random.nextInt(16), 0, 8 + (chunkZ << 4) + random.nextInt(16));
+		BlockPos origin = new BlockPos((chunkX << 4) + random.nextInt(16) + 8 - size.getX()/2, 0, (chunkZ << 4) + random.nextInt(16) + 8 - size.getZ()/2);
-
-		BlockPos size = template.transformedSize(settings.getRotation());
 
 		// Estimate a starting height for searching for the floor
 		BlockPos centre = world.getTopSolidOrLiquidBlock(new BlockPos(origin.add(size.getX()/2, 0, size.getZ()/2)));
@@ -150,6 +150,9 @@ public abstract class WorldGenSurfaceStructure extends WorldGenWizardryStructure
 			for(int y1 = boundingBox.minY - border; y1 <= y + border; y1++){
 				for(int z = boundingBox.minZ - border; z <= boundingBox.maxZ + border; z++){
 					BlockPos pos = new BlockPos(x, y1, z);
+					// Skip blocks that haven't been generated yet
+					// If you think about it, there can't possibly be floating trees in unloaded chunks anyway
+					if(!world.isBlockLoaded(pos)) continue;
 					if(world.getBlockState(pos).getBlock() instanceof BlockLeaves) leaves.add(pos);
 				}
 			}

src/main/java/electroblob/wizardry/worldgen/WorldGenUndergroundLibraryRuins.java

@@ -96,7 +96,7 @@ public class WorldGenUndergroundLibraryRuins extends WorldGenUndergroundStructur
 				}
 		);
 
-		template.addBlocksToWorld(world, origin, processor, settings, 2);
+		template.addBlocksToWorld(world, origin, processor, settings, 2 | 16);
 
 		WizardryAntiqueAtlasIntegration.markLibrary(world, origin.getX(), origin.getZ());
 	}

src/main/java/electroblob/wizardry/worldgen/WorldGenUndergroundStructure.java

@@ -25,9 +25,13 @@ public abstract class WorldGenUndergroundStructure extends WorldGenWizardryStruc
 	@Override
 	protected BlockPos attemptPosition(Template template, PlacementSettings settings, Random random, World world, int chunkX, int chunkZ, String structureFile){
 
-		BlockPos origin = new BlockPos(8 + (chunkX << 4) + random.nextInt(16), 20 + random.nextInt(40), 8 + (chunkZ << 4) + random.nextInt(16));
-
 		BlockPos size = template.transformedSize(settings.getRotation());
+
+		// Offset by (8, 8) to minimise cascading worldgen lag, MINUS half the width of the structure (important!)
+		// See https://www.reddit.com/r/feedthebeast/cowmments/5x0twz/investigating_extreme_worldgen_lag/?ref=share&ref_source=embed&utm_content=title&utm_medium=post_embed&utm_name=c07cbb545f74487793783012794733d8&utm_source=embedly&utm_term=5x0twz
+		// Multiplying and left-shifting are identical but it's good practice to bitshift here I guess
+		BlockPos origin = new BlockPos((chunkX << 4) + random.nextInt(16) + 8 - size.getX()/2, 20 + random.nextInt(40), (chunkZ << 4) + random.nextInt(16) + 8 - size.getZ()/2);
+
 		BlockPos corner = origin.add(size.getX(), 1, size.getZ()); // Need not iterate through everything
 
 		// Criteria for a valid position:

src/main/java/electroblob/wizardry/worldgen/WorldGenWizardTower.java

@@ -101,7 +101,7 @@ public class WorldGenWizardTower extends WorldGenSurfaceStructure {
 				(w, p, i) -> {if(i.blockState.getBlock() != Blocks.AIR) blocksPlaced.add(p); return i;}
 		);
 
-		template.addBlocksToWorld(world, origin, processor, settings, 2);
+		template.addBlocksToWorld(world, origin, processor, settings, 2 | 16);
 
 		WizardryAntiqueAtlasIntegration.markTower(world, origin.getX(), origin.getZ());