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Fix some issues with the retract event & sticky pistons #12985

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Fix some issues with the retract event & sticky pistons #12985

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e342dbf
Fix some issues with the retract event & sticky pistons
Aug 17, 2025
be49ee9
format
Lulu13022002 Aug 27, 2025
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111 changes: 101 additions & 10 deletions ...-server/patches/sources/net/minecraft/world/level/block/piston/PistonBaseBlock.java.patch
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Original file line number Diff line number Diff line change
Expand Up @@ -13,13 +13,22 @@
BlockState blockState = state.setValue(EXTENDED, true);
if (!level.isClientSide) {
boolean neighborSignal = this.getNeighborSignal(level, pos, direction);
@@ -182,10 +_,17 @@
@@ -165,7 +_,7 @@
}

if (id == 0) {
- if (!this.moveBlocks(level, pos, direction, true)) {
+ if (this.moveBlocks(level, state, pos, direction, true) != MoveBlocksResult.SUCCESS) { // Paper - Fix sticky piston retract event
return false;
}

@@ -182,40 +_,70 @@
.defaultBlockState()
.setValue(MovingPistonBlock.FACING, direction)
.setValue(MovingPistonBlock.TYPE, this.isSticky ? PistonType.STICKY : PistonType.DEFAULT);
+ // Paper start - Fix sticky pistons and BlockPistonRetractEvent; Move empty piston retract call to fix multiple event fires
+ if (!this.isSticky) {
+ if (!new org.bukkit.event.block.BlockPistonRetractEvent(org.bukkit.craftbukkit.block.CraftBlock.at(level, pos), java.util.Collections.emptyList(), org.bukkit.craftbukkit.block.CraftBlock.notchToBlockFace(direction)).callEvent()) {
+ if (!new org.bukkit.event.block.BlockPistonRetractEvent(org.bukkit.craftbukkit.block.CraftBlock.at(level, pos), java.util.Collections.emptyList(), org.bukkit.craftbukkit.block.CraftBlock.notchToBlockFace(direction.getOpposite())).callEvent()) {
+ return false;
+ }
+ }
Expand All @@ -32,20 +41,50 @@
)
);
level.updateNeighborsAt(pos, blockState1.getBlock());
@@ -209,13 +_,27 @@
- blockState1.updateNeighbourShapes(level, pos, 2);
+ if (!this.isSticky) blockState1.updateNeighbourShapes(level, pos, Block.UPDATE_CLIENTS); // Paper - move sticky update down until after piston event
if (this.isSticky) {
BlockPos blockPos = pos.offset(direction.getStepX() * 2, direction.getStepY() * 2, direction.getStepZ() * 2);
BlockState blockState2 = level.getBlockState(blockPos);
- boolean flag = false;
+ boolean isWorkingMovingPiston = false; // Paper - OBFHELPER
if (blockState2.is(Blocks.MOVING_PISTON)
&& level.getBlockEntity(blockPos) instanceof PistonMovingBlockEntity pistonMovingBlockEntity
&& pistonMovingBlockEntity.getDirection() == direction
&& pistonMovingBlockEntity.isExtending()) {
pistonMovingBlockEntity.finalTick();
- flag = true;
+ isWorkingMovingPiston = true; // Paper - OBFHELPER
}

- if (!flag) {
+ if (isWorkingMovingPiston) blockState1.updateNeighbourShapes(level, pos, Block.UPDATE_CLIENTS); // Paper - Fix sticky piston retract event; Move update to after event call
+ if (!isWorkingMovingPiston) { // Paper - OBFHELPER
if (id != 1
|| blockState2.isAir()
|| !isPushable(blockState2, level, blockPos, direction.getOpposite(), false, direction)
|| blockState2.getPistonPushReaction() != PushReaction.NORMAL
&& !blockState2.is(Blocks.PISTON)
&& !blockState2.is(Blocks.STICKY_PISTON)) {
+ // Paper start - Fix sticky pistons and BlockPistonRetractEvent; fire BlockPistonRetractEvent for sticky pistons retracting nothing (air)
+ if (id == TRIGGER_CONTRACT && blockState1.isAir()) {
+ if (!new org.bukkit.event.block.BlockPistonRetractEvent(org.bukkit.craftbukkit.block.CraftBlock.at(level, pos), java.util.Collections.emptyList(), org.bukkit.craftbukkit.block.CraftBlock.notchToBlockFace(direction)).callEvent()) {
+ // Paper start - Fix sticky pistons and BlockPistonRetractEvent; fire BlockPistonRetractEvent for sticky pistons retracting un-pushable block or air
+ if (id == TRIGGER_CONTRACT) {
+ if (!new org.bukkit.event.block.BlockPistonRetractEvent(org.bukkit.craftbukkit.block.CraftBlock.at(level, pos), java.util.Collections.emptyList(), org.bukkit.craftbukkit.block.CraftBlock.notchToBlockFace(direction.getOpposite())).callEvent()) {
+ level.removeBlockEntity(pos);
+ level.setBlock(pos, state, Block.UPDATE_KNOWN_SHAPE | Block.UPDATE_SKIP_ON_PLACE);
+ return false;
+ }
+ }
+ blockState1.updateNeighbourShapes(level, pos, Block.UPDATE_CLIENTS); // move this from right after creating the moving piston block entity to after the event call
+ // Paper end - Fix sticky pistons and BlockPistonRetractEvent
level.removeBlock(pos.relative(direction), false);
} else {
this.moveBlocks(level, pos, direction, false);
- this.moveBlocks(level, pos, direction, false);
+ // Paper start - Fix sticky piston retract event
+ if (this.moveBlocks(level, state, pos, direction, false) == MoveBlocksResult.CANCEL) {
+ return false;
+ }
+ blockState1.updateNeighbourShapes(level, pos, Block.UPDATE_CLIENTS); // move this from right after creating the moving piston block entity to after the event call
+ // Paper end - Fix sticky piston retract event
}
}
} else {
Expand All @@ -70,9 +109,47 @@
return false;
} else if (state.isAir()) {
return true;
@@ -282,12 +_,54 @@
@@ -258,15 +_,31 @@
}
}

- private boolean moveBlocks(Level level, BlockPos pos, Direction facing, boolean extending) {
+ private enum MoveBlocksResult { FAIL, CANCEL, SUCCESS } // Paper - Fix sticky piston retract event
+
+ private MoveBlocksResult moveBlocks(Level level, BlockState oldState, BlockPos pos, Direction facing, boolean extending) { // Paper - Fix sticky piston retract event
BlockPos blockPos = pos.relative(facing);
- if (!extending && level.getBlockState(blockPos).is(Blocks.PISTON_HEAD)) {
+ // Paper start - Fix sticky piston retract event
+ final BlockState pistonHead = level.getBlockState(blockPos);
+ if (!extending && pistonHead.is(Blocks.PISTON_HEAD)) {
+ // Paper end - Fix sticky piston retract event
level.setBlock(blockPos, Blocks.AIR.defaultBlockState(), 276);
}

PistonStructureResolver pistonStructureResolver = new PistonStructureResolver(level, pos, facing, extending);
+ Direction direction = extending ? facing : facing.getOpposite(); // Paper - Fix sticky piston retract event; moved from below
if (!pistonStructureResolver.resolve()) {
- return false;
+ // Paper start - Fix sticky piston retract event; Fire event if piston retracts without moving blocks
+ if (!extending) {
+ if (!new org.bukkit.event.block.BlockPistonRetractEvent(org.bukkit.craftbukkit.block.CraftBlock.at(level, pos), java.util.Collections.emptyList(), org.bukkit.craftbukkit.block.CraftBlock.notchToBlockFace(direction)).callEvent()) {
+ level.removeBlockEntity(pos);
+ level.setBlock(pos, oldState, Block.UPDATE_KNOWN_SHAPE | Block.UPDATE_SKIP_ON_PLACE);
+ level.setBlock(blockPos, pistonHead, Block.UPDATE_KNOWN_SHAPE | Block.UPDATE_SKIP_ON_PLACE);
+ return MoveBlocksResult.CANCEL;
+ }
+ }
+ return MoveBlocksResult.FAIL;
+ // Paper end - Fix sticky piston retract event
} else {
Map<BlockPos, BlockState> map = Maps.newHashMap();
List<BlockPos> toPush = pistonStructureResolver.getToPush();
@@ -280,14 +_,61 @@

List<BlockPos> toDestroy = pistonStructureResolver.getToDestroy();
BlockState[] blockStates = new BlockState[toPush.size() + toDestroy.size()];
Direction direction = extending ? facing : facing.getOpposite();
- Direction direction = extending ? facing : facing.getOpposite();
+ // Paper - Fix sticky piston retract event; moved up
int i = 0;
+ // CraftBukkit start
+ final org.bukkit.block.Block bukkitBlock = org.bukkit.craftbukkit.block.CraftBlock.at(level, pos);
Expand Down Expand Up @@ -105,6 +182,11 @@
+ event = new org.bukkit.event.block.BlockPistonRetractEvent(bukkitBlock, blocks, org.bukkit.craftbukkit.block.CraftBlock.notchToBlockFace(direction));
+ }
+ if (!event.callEvent()) {
+ if (!extending) {
+ level.removeBlockEntity(pos);
+ level.setBlock(pos, oldState, Block.UPDATE_KNOWN_SHAPE | Block.UPDATE_SKIP_ON_PLACE);
+ level.setBlock(blockPos, pistonHead, Block.UPDATE_KNOWN_SHAPE | Block.UPDATE_SKIP_ON_PLACE);
+ }
+ for (BlockPos brokenPos : broken) {
+ level.sendBlockUpdated(brokenPos, Blocks.AIR.defaultBlockState(), level.getBlockState(brokenPos), Block.UPDATE_ALL);
+ }
Expand All @@ -113,7 +195,7 @@
+ movedPos = movedPos.relative(direction);
+ level.sendBlockUpdated(movedPos, Blocks.AIR.defaultBlockState(), level.getBlockState(movedPos), Block.UPDATE_ALL);
+ }
+ return false;
+ return MoveBlocksResult.CANCEL;
+ }
+ // CraftBukkit end

Expand Down Expand Up @@ -156,3 +238,12 @@
blockStates[i++] = blockState1;
}

@@ -359,7 +_,7 @@
level.updateNeighborsAt(blockPos, Blocks.PISTON_HEAD, orientation);
}

- return true;
+ return MoveBlocksResult.SUCCESS; // Paper - Fix sticky piston retract event
}
}

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