Sound engine running full steam

- Play at most 4 steam engine sounds at once per side of a boiler
- 3 seems to be too few for this case as there's still a perceptible
  difference between 3 and 4 sounds per side
- Track which positions want to play the sound in any given rolling
  window of ticks, and roll dice to decide which positions actually get
  to play
- Introduce SoundPool to track that and explain the perception stuffs

src/main/java/com/simibubi/create/content/fluids/tank/BoilerData.java

@@ -1,6 +1,7 @@
 package com.simibubi.create.content.fluids.tank;
 
 import java.util.Arrays;
+import java.util.EnumMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
@@ -8,6 +9,7 @@ import java.util.Set;
 import org.jetbrains.annotations.NotNull;
 
 import com.simibubi.create.AllBlocks;
+import com.simibubi.create.AllSoundEvents;
 import com.simibubi.create.Create;
 import com.simibubi.create.content.decoration.steamWhistle.WhistleBlock;
 import com.simibubi.create.content.decoration.steamWhistle.WhistleBlockEntity;
@@ -29,6 +31,8 @@ import net.minecraft.core.Direction;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.network.chat.Component;
 import net.minecraft.network.chat.MutableComponent;
+import net.minecraft.sounds.SoundEvents;
+import net.minecraft.sounds.SoundSource;
 import net.minecraft.util.Mth;
 import net.minecraft.world.level.Level;
 import net.minecraft.world.level.block.state.BlockState;
@@ -65,10 +69,25 @@ public class BoilerData {
 
 	public LerpedFloat gauge = LerpedFloat.linear();
 
+	// client only sound control
+
+	// re-use the same lambda for each side
+	private final SoundPool.Sound sound = (level, pos) -> {
+		float volume = 3f / Math.max(2, attachedEngines / 6);
+		float pitch = 1.18f - level.random.nextFloat() * .25f;
+		level.playLocalSound(pos.getX(), pos.getY(), pos.getZ(),
+			SoundEvents.CANDLE_EXTINGUISH, SoundSource.BLOCKS, volume, pitch, false);
+
+		AllSoundEvents.STEAM.playAt(level, pos, volume / 16, .8f, false);
+	};
+	// separate pools for each side so they sound distinct when standing at corners of the boiler
+	private final EnumMap<Direction, SoundPool> pools = new EnumMap<>(Direction.class);
+
 	public void tick(FluidTankBlockEntity controller) {
 		if (!isActive())
 			return;
 		if (controller.getLevel().isClientSide) {
+			pools.values().forEach(p -> p.play(controller.getLevel()));
 			gauge.tickChaser();
 			float current = gauge.getValue(1);
 			if (current > 1 && Create.RANDOM.nextFloat() < 1 / 2f)
@@ -105,6 +124,15 @@ public class BoilerData {
 		controller.notifyUpdate();
 	}
 
+	public void queueSoundOnSide(BlockPos pos, Direction side) {
+		SoundPool pool = pools.get(side);
+		if (pool == null) {
+			pool = new SoundPool(4, 2, sound);
+			pools.put(side, pool);
+		}
+		pool.queueAt(pos);
+	}
+
 	public int getTheoreticalHeatLevel() {
 		return activeHeat;
 	}

src/main/java/com/simibubi/create/content/fluids/tank/SoundPool.java

@@ -0,0 +1,101 @@
+package com.simibubi.create.content.fluids.tank;
+
+import it.unimi.dsi.fastutil.longs.LongArrayList;
+import it.unimi.dsi.fastutil.longs.LongList;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Vec3i;
+import net.minecraft.world.level.Level;
+
+/**
+ * One person walking sounds like one person walking, and you can easily distinguish where they are.
+ *
+ * <br>With two people walking, you can still pick out which footsteps belong to which person.
+ *
+ * <br>Try and listen to three people walking in a group, however, and you'll find that you can't distinguish
+ * individual footsteps anymore. You now just hear the sound of a group of people walking.
+ *
+ * <p>You'll likely find that you perceive any number of people walking in a group as a single distinguishable sound.
+ * This class is a helper to take advantage of that for sound effects in Create to avoid saturating the sound engine
+ * without a perceptible loss in quality.
+ *
+ * <p>NOTE: It's up to the user of this class to decide how to group sounds such that they are perceived as a single
+ * sound. There are no spatial calculations made here.
+ */
+public class SoundPool {
+	/**
+	 * The maximum number of sounds that can be played at once.
+	 */
+	private final int maxConcurrent;
+	/**
+	 * The number of ticks to wait before playing sounds. Useful if sounds are queued across many block entities,
+	 * and you don't have control over the tick order.
+	 */
+	private final int mergeTicks;
+
+	private final Sound sound;
+
+	private final LongList queuedPositions = new LongArrayList();
+
+	private final BlockPos.MutableBlockPos pos = new BlockPos.MutableBlockPos();
+
+	private int ticks = 0;
+
+	public SoundPool(int maxConcurrent, int mergeTicks, Sound sound) {
+		this.maxConcurrent = maxConcurrent;
+		this.sound = sound;
+		this.mergeTicks = mergeTicks;
+	}
+
+	public void queueAt(BlockPos pos) {
+		queueAt(pos.asLong());
+	}
+
+	public void queueAt(long pos) {
+		queuedPositions.add(pos);
+	}
+
+	public void play(Level level) {
+		if (queuedPositions.isEmpty()) {
+			return;
+		}
+
+		ticks++;
+
+		if (ticks < mergeTicks) {
+			// Wait for more sounds to be queued in further ticks.
+			return;
+		}
+
+		ticks = 0;
+
+		var numberOfPositions = queuedPositions.size();
+
+		if (numberOfPositions <= maxConcurrent) {
+			// Fewer sound positions than maxConcurrent, play them all.
+			for (long pos : queuedPositions) {
+				playAt(level, pos);
+			}
+		} else {
+			// Roll for n random positions and play there.
+			while (!queuedPositions.isEmpty() && queuedPositions.size() > numberOfPositions - maxConcurrent) {
+				rollNextPosition(level);
+			}
+		}
+
+		queuedPositions.clear();
+	}
+
+	private void rollNextPosition(Level level) {
+		int index = level.random.nextInt(queuedPositions.size());
+		long pos = queuedPositions.removeLong(index);
+		playAt(level, pos);
+	}
+
+	private void playAt(Level level, long pos) {
+		sound.playAt(level, this.pos.set(pos));
+	}
+
+	public interface Sound {
+		void playAt(Level level, Vec3i pos);
+	}
+}

src/main/java/com/simibubi/create/content/kinetics/steamEngine/SteamEngineBlockEntity.java

@@ -6,7 +6,6 @@ import java.util.List;
 import javax.annotation.Nullable;
 
 import com.simibubi.create.AllBlocks;
-import com.simibubi.create.AllSoundEvents;
 import com.simibubi.create.content.contraptions.bearing.WindmillBearingBlockEntity.RotationDirection;
 import com.simibubi.create.content.equipment.goggles.IHaveGoggleInformation;
 import com.simibubi.create.content.fluids.tank.FluidTankBlockEntity;
@@ -26,8 +25,6 @@ import net.minecraft.core.Direction;
 import net.minecraft.core.Direction.Axis;
 import net.minecraft.core.Direction.AxisDirection;
 import net.minecraft.network.chat.Component;
-import net.minecraft.sounds.SoundEvents;
-import net.minecraft.sounds.SoundSource;
 import net.minecraft.util.Mth;
 import net.minecraft.world.level.block.entity.BlockEntity;
 import net.minecraft.world.level.block.entity.BlockEntityType;
@@ -208,11 +205,7 @@ public class SteamEngineBlockEntity extends SmartBlockEntity implements IHaveGog
 		if (sourceBE != null) {
 			FluidTankBlockEntity controller = sourceBE.getControllerBE();
 			if (controller != null && controller.boiler != null) {
-				float volume = 3f / Math.max(2, controller.boiler.attachedEngines / 6);
-				float pitch = 1.18f - level.random.nextFloat() * .25f;
-				level.playLocalSound(worldPosition.getX(), worldPosition.getY(), worldPosition.getZ(),
-					SoundEvents.CANDLE_EXTINGUISH, SoundSource.BLOCKS, volume, pitch, false);
-				AllSoundEvents.STEAM.playAt(level, worldPosition, volume / 16, .8f, false);
+				controller.boiler.queueSoundOnSide(worldPosition, SteamEngineBlock.getFacing(getBlockState()));
 			}
 		}