Allow structure void to be used in structures to define literal air

Author: Swedz

src/main/java/aztech/modern_industrialization/machines/multiblocks/ShapeMatcher.java

@@ -284,11 +284,13 @@ public int buildMultiblock(Level level, boolean structureBlocks) {
                 var optionalStructureBlock = member.asStructureBlock(pos, structureBlocks);
                 if (optionalStructureBlock.isPresent()) {
                     BlockState state = optionalStructureBlock.get().getFirst();
-                    FastBlockEntity be = optionalStructureBlock.get().getSecond();
                     level.setBlockAndUpdate(pos, state);
-                    level.setBlockEntity(be);
-                    be.setChanged();
-                    be.sync();
+                    FastBlockEntity be = optionalStructureBlock.get().getSecond();
+                    if (be != null) {
+                        level.setBlockEntity(be);
+                        be.setChanged();
+                        be.sync();
+                    }
                     setBlocks++;
                     continue;
                 } else if (member instanceof SimpleStructureMember simpleMember) {

src/main/java/aztech/modern_industrialization/machines/multiblocks/structure/MIStructureTemplateManager.java

@@ -127,9 +127,12 @@ public static StructureResult fromWorld(ResourceLocation id, Level level,
 
         for (BlockPos pos : BlockPos.betweenClosed(minPos, maxPos)) {
             BlockState state = toTemplateState(level, pos, level.getBlockState(pos), controllerDirection);
-            if (state.isAir() || state.is(Blocks.STRUCTURE_VOID)) {
+            if (state.isAir()) {
                 continue;
             }
+            if (state.is(Blocks.STRUCTURE_VOID)) {
+                state = Blocks.AIR.defaultBlockState();
+            }
             BlockEntity blockEntity = level.getBlockEntity(pos);
 
             boolean isIgnoreNBT = ignoreNBTPositions.contains(pos);

src/main/java/aztech/modern_industrialization/machines/multiblocks/structure/member/HatchStructureMember.java

@@ -40,6 +40,7 @@
 import java.util.Optional;
 import net.minecraft.core.BlockPos;
 import net.minecraft.world.level.block.state.BlockState;
+import org.jetbrains.annotations.Nullable;
 
 public final class HatchStructureMember extends SimpleStructureMember {
     public static final MapCodec<HatchStructureMember> CODEC = RecordCodecBuilder.mapCodec(instance -> instance
@@ -79,7 +80,7 @@ public StructureMemberType<?> type() {
     }
 
     @Override
-    public Optional<Pair<BlockState, FastBlockEntity>> asStructureBlock(BlockPos pos, boolean required) {
+    public Optional<Pair<BlockState, @Nullable FastBlockEntity>> asStructureBlock(BlockPos pos, boolean required) {
         if (required) {
             var state = MIBlock.STRUCTURE_MULTIBLOCK_MEMBER.asBlock().defaultBlockState();
             state = state.setValue(StructureMultiblockMemberBlock.MODE, StructureMemberMode.HATCH);

src/main/java/aztech/modern_industrialization/machines/multiblocks/structure/member/LiteralStructureMember.java

@@ -32,6 +32,7 @@
 import java.util.List;
 import java.util.Optional;
 import net.minecraft.core.BlockPos;
+import net.minecraft.world.level.block.Blocks;
 import net.minecraft.world.level.block.entity.BlockEntity;
 import net.minecraft.world.level.block.state.BlockState;
 import org.jetbrains.annotations.Nullable;
@@ -59,7 +60,10 @@ public boolean matchesState(BlockState state, @Nullable BlockEntity blockEntity)
     }
 
     @Override
-    public Optional<Pair<BlockState, FastBlockEntity>> asStructureBlock(BlockPos pos, boolean required) {
+    public Optional<Pair<BlockState, @Nullable FastBlockEntity>> asStructureBlock(BlockPos pos, boolean required) {
+        if (preview.state().get().isAir()) {
+            return Optional.of(new Pair<>(Blocks.STRUCTURE_VOID.defaultBlockState(), null));
+        }
         return Optional.empty();
     }
 

src/main/java/aztech/modern_industrialization/machines/multiblocks/structure/member/SimpleStructureMember.java

@@ -82,7 +82,7 @@ public StructureMemberType<?> type() {
     }
 
     @Override
-    public Optional<Pair<BlockState, FastBlockEntity>> asStructureBlock(BlockPos pos, boolean required) {
+    public Optional<Pair<BlockState, @Nullable FastBlockEntity>> asStructureBlock(BlockPos pos, boolean required) {
         if (required) {
             var state = MIBlock.STRUCTURE_MULTIBLOCK_MEMBER.asBlock().defaultBlockState();
             state = state.setValue(StructureMultiblockMemberBlock.MODE, StructureMemberMode.SIMPLE);