Optimize jigsaw free space tracking with cuboid difference shapes

common/src/main/java/net/caffeinemc/mods/lithium/mixin/gen/jigsaw_free_space/JigsawPlacementMixin.java

@@ -0,0 +1,28 @@
+package net.caffeinemc.mods.lithium.mixin.gen.jigsaw_free_space;
+
+import net.caffeinemc.mods.lithium.common.shapes.VoxelShapeCuboidDifference;
+import net.minecraft.world.level.levelgen.structure.pools.JigsawPlacement;
+import net.minecraft.world.phys.shapes.VoxelShape;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.ModifyVariable;
+
+@Mixin(JigsawPlacement.class)
+public class JigsawPlacementMixin {
+
+    /**
+     * Replace the initial free space shape (usually the max-radius box minus the start piece's box) with a
+     * cuboid-list-based representation. The subsequent piece placement queries and free space subtractions in
+     * {@code Placer#tryPlacingChildren} then operate on the cuboid lists directly instead of running vanilla's
+     * costly voxel-based shape joins. If the shape cannot be represented exactly, it is passed through unchanged
+     * and all operations fall back to vanilla.
+     */
+    @ModifyVariable(
+            method = "addPieces(Lnet/minecraft/world/level/levelgen/RandomState;IZLnet/minecraft/world/level/chunk/ChunkGenerator;Lnet/minecraft/world/level/levelgen/structure/templatesystem/StructureTemplateManager;Lnet/minecraft/world/level/LevelHeightAccessor;Lnet/minecraft/util/RandomSource;Lnet/minecraft/core/Registry;Lnet/minecraft/world/level/levelgen/structure/PoolElementStructurePiece;Ljava/util/List;Lnet/minecraft/world/phys/shapes/VoxelShape;Lnet/minecraft/world/level/levelgen/structure/pools/alias/PoolAliasLookup;Lnet/minecraft/world/level/levelgen/structure/templatesystem/LiquidSettings;)V",
+            at = @At("HEAD"),
+            argsOnly = true
+    )
+    private static VoxelShape useCuboidDifferenceFreeSpace(VoxelShape freeSpace) {
+        return VoxelShapeCuboidDifference.tryConvert(freeSpace);
+    }
+}

common/src/main/java/net/caffeinemc/mods/lithium/mixin/gen/jigsaw_free_space/JigsawPlacementPlacerMixin.java

@@ -0,0 +1,68 @@
+package net.caffeinemc.mods.lithium.mixin.gen.jigsaw_free_space;
+
+import com.llamalad7.mixinextras.injector.wrapoperation.Operation;
+import com.llamalad7.mixinextras.injector.wrapoperation.WrapOperation;
+import net.caffeinemc.mods.lithium.common.shapes.VoxelShapeCuboidDifference;
+import net.minecraft.world.phys.AABB;
+import net.minecraft.world.phys.shapes.BooleanOp;
+import net.minecraft.world.phys.shapes.VoxelShape;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+
+@Mixin(targets = "net.minecraft.world.level.levelgen.structure.pools.JigsawPlacement$Placer")
+public class JigsawPlacementPlacerMixin {
+    private static final String TRY_PLACING_CHILDREN = "tryPlacingChildren(Lnet/minecraft/world/level/levelgen/structure/PoolElementStructurePiece;Lorg/apache/commons/lang3/mutable/MutableObject;IZLnet/minecraft/world/level/LevelHeightAccessor;Lnet/minecraft/world/level/levelgen/RandomState;Lnet/minecraft/world/level/levelgen/structure/pools/alias/PoolAliasLookup;Lnet/minecraft/world/level/levelgen/structure/templatesystem/LiquidSettings;)V";
+
+    /**
+     * The free space inside the current piece (used when placing children on the interior of a piece) starts out
+     * as a single cuboid, which the cuboid-list-based representation can express directly.
+     */
+    @WrapOperation(
+            method = TRY_PLACING_CHILDREN,
+            at = @At(value = "INVOKE", target = "Lnet/minecraft/world/phys/shapes/Shapes;create(Lnet/minecraft/world/phys/AABB;)Lnet/minecraft/world/phys/shapes/VoxelShape;", ordinal = 0)
+    )
+    private VoxelShape createInteriorFreeSpace(AABB cuboid, Operation<VoxelShape> original) {
+        VoxelShape freeSpace = VoxelShapeCuboidDifference.tryCreate(cuboid);
+        if (freeSpace != null) {
+            return freeSpace;
+        }
+        return original.call(cuboid);
+    }
+
+    /**
+     * A candidate piece is rejected when any part of its deflated bounding box lies outside the free space.
+     * For the cuboid-list-based free space this test is a handful of coordinate comparisons instead of a
+     * voxel-based shape join.
+     */
+    @WrapOperation(
+            method = TRY_PLACING_CHILDREN,
+            at = @At(value = "INVOKE", target = "Lnet/minecraft/world/phys/shapes/Shapes;joinIsNotEmpty(Lnet/minecraft/world/phys/shapes/VoxelShape;Lnet/minecraft/world/phys/shapes/VoxelShape;Lnet/minecraft/world/phys/shapes/BooleanOp;)Z")
+    )
+    private boolean testCandidateOutsideFreeSpace(VoxelShape freeSpace, VoxelShape candidate, BooleanOp op, Operation<Boolean> original) {
+        if (op == BooleanOp.ONLY_SECOND && freeSpace instanceof VoxelShapeCuboidDifference cuboidDifference) {
+            int result = cuboidDifference.exceedsFreeSpace(candidate);
+            if (result != VoxelShapeCuboidDifference.FALLBACK) {
+                return result == VoxelShapeCuboidDifference.EXCEEDS;
+            }
+        }
+        return original.call(VoxelShapeCuboidDifference.unwrap(freeSpace), VoxelShapeCuboidDifference.unwrap(candidate), op);
+    }
+
+    /**
+     * Subtracting a placed piece's bounding box from the free space only appends the cuboid to the list instead
+     * of running a voxel-based shape join.
+     */
+    @WrapOperation(
+            method = TRY_PLACING_CHILDREN,
+            at = @At(value = "INVOKE", target = "Lnet/minecraft/world/phys/shapes/Shapes;joinUnoptimized(Lnet/minecraft/world/phys/shapes/VoxelShape;Lnet/minecraft/world/phys/shapes/VoxelShape;Lnet/minecraft/world/phys/shapes/BooleanOp;)Lnet/minecraft/world/phys/shapes/VoxelShape;")
+    )
+    private VoxelShape subtractFromFreeSpace(VoxelShape freeSpace, VoxelShape placedPiece, BooleanOp op, Operation<VoxelShape> original) {
+        if (op == BooleanOp.ONLY_FIRST && freeSpace instanceof VoxelShapeCuboidDifference cuboidDifference) {
+            VoxelShape result = cuboidDifference.trySubtract(placedPiece);
+            if (result != null) {
+                return result;
+            }
+        }
+        return original.call(VoxelShapeCuboidDifference.unwrap(freeSpace), VoxelShapeCuboidDifference.unwrap(placedPiece), op);
+    }
+}

common/src/main/java/net/caffeinemc/mods/lithium/mixin/gen/jigsaw_free_space/package-info.java

@@ -0,0 +1,4 @@
+@MixinConfigOption(description = "Jigsaw structure placement (e.g. villages, bastions, trial chambers) tracks the remaining free space using cuboid lists instead of repeatedly joining VoxelShapes")
+package net.caffeinemc.mods.lithium.mixin.gen.jigsaw_free_space;
+
+import net.caffeinemc.gradle.MixinConfigOption;

common/src/main/resources/lithium.mixins.json

@@ -164,6 +164,8 @@
     "experimental.entity.block_caching.suffocation.EntityMixin",
     "experimental.entity.item_entity_merging.ItemEntityMixin",
     "gen.cached_generator_settings.NoiseBasedChunkGeneratorMixin",
+    "gen.jigsaw_free_space.JigsawPlacementMixin",
+    "gen.jigsaw_free_space.JigsawPlacementPlacerMixin",
     "math.fast_blockpos.BlockPosMixin",
     "math.fast_blockpos.DirectionMixin",
     "math.fast_util.AABBMixin",