Mind the gap

- Fixed trapdoors and doors causing a contraption to flicker when activated
- Hastily added a few ticks of extra time before a contraption is discarded on the client to close the time gap between entity and chunk render

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/AbstractContraptionEntity.java

@@ -90,6 +90,15 @@ public abstract class AbstractContraptionEntity extends Entity implements IEntit
 	protected boolean prevPosInvalid;
 	private boolean skipActorStop;
 
+	/*
+	 * staleTicks are a band-aid to prevent a frame or two of missing blocks between
+	 * contraption discard and off-thread block placement on disassembly
+	 * 
+	 * FIXME this timeout should be longer but then also cancelled early based on a
+	 * chunk rebuild listener
+	 */
+	public int staleTicks = 3;
+
 	public AbstractContraptionEntity(EntityType<?> entityTypeIn, Level worldIn) {
 		super(entityTypeIn, worldIn);
 		prevPosInvalid = true;
@@ -168,7 +177,7 @@ public abstract class AbstractContraptionEntity extends Entity implements IEntit
 		callback.accept(passenger, transformedVector.x,
 			transformedVector.y + SeatEntity.getCustomEntitySeatOffset(passenger) - 1 / 8f, transformedVector.z);
 	}
-	
+
 	protected Vec3 getPassengerPosition(Entity passenger, float partialTicks) {
 		UUID id = passenger.getUUID();
 		if (passenger instanceof OrientedContraptionEntity) {
@@ -309,6 +318,14 @@ public abstract class AbstractContraptionEntity extends Entity implements IEntit
 		tickContraption();
 		super.tick();
 
+		if (level.isClientSide())
+			DistExecutor.unsafeRunWhenOn(Dist.CLIENT, () -> () -> {
+				if (!contraption.deferInvalidate)
+					return;
+				contraption.deferInvalidate = false;
+				ContraptionRenderDispatcher.invalidate(contraption);
+			});
+
 		if (!(level instanceof ServerLevelAccessor sl))
 			return;
 
@@ -695,7 +712,7 @@ public abstract class AbstractContraptionEntity extends Entity implements IEntit
 		StructureBlockInfo info = contraption.blocks.get(localPos);
 		contraption.blocks.put(localPos, new StructureBlockInfo(info.pos, newState, info.nbt));
 		if (info.state != newState && !(newState.getBlock() instanceof SlidingDoorBlock))
-			DistExecutor.unsafeRunWhenOn(Dist.CLIENT, () -> () -> ContraptionRenderDispatcher.invalidate(contraption));
+			contraption.deferInvalidate = true;
 		contraption.invalidateColliders();
 	}
 
@@ -851,4 +868,8 @@ public abstract class AbstractContraptionEntity extends Entity implements IEntit
 		return initialized;
 	}
 
+	public boolean isAliveOrStale() {
+		return isAlive() || level.isClientSide() ? staleTicks > 0 : false;
+	}
+
 }

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/Contraption.java

@@ -151,6 +151,7 @@ public abstract class Contraption {
 	public List<BlockEntity> specialRenderedTileEntities;
 
 	protected ContraptionWorld world;
+	public boolean deferInvalidate;
 
 	public Contraption() {
 		blocks = new HashMap<>();

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/ContraptionHandler.java

@@ -45,10 +45,15 @@ public class ContraptionHandler {
 		for (Iterator<WeakReference<AbstractContraptionEntity>> iterator = values.iterator(); iterator.hasNext();) {
 			WeakReference<AbstractContraptionEntity> weakReference = iterator.next();
 			AbstractContraptionEntity contraptionEntity = weakReference.get();
-			if (contraptionEntity == null || !contraptionEntity.isAlive()) {
+			if (contraptionEntity == null || !contraptionEntity.isAliveOrStale()) {
 				iterator.remove();
 				continue;
 			}
+			if (!contraptionEntity.isAlive()) {
+				contraptionEntity.staleTicks--;
+				continue;
+			}
+			
 			ContraptionCollider.collideEntities(contraptionEntity);
 		}
 	}

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/MovingInteractionBehaviour.java

@@ -2,16 +2,11 @@ package com.simibubi.create.content.contraptions.components.structureMovement;
 
 import org.apache.commons.lang3.tuple.MutablePair;
 
-import com.simibubi.create.content.contraptions.components.structureMovement.render.ContraptionRenderDispatcher;
-
 import net.minecraft.core.BlockPos;
 import net.minecraft.world.InteractionHand;
 import net.minecraft.world.entity.Entity;
 import net.minecraft.world.entity.player.Player;
 import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplate.StructureBlockInfo;
-import net.minecraftforge.api.distmarker.Dist;
-import net.minecraftforge.api.distmarker.OnlyIn;
-import net.minecraftforge.fml.DistExecutor;
 
 public abstract class MovingInteractionBehaviour {
 
@@ -22,7 +17,7 @@ public abstract class MovingInteractionBehaviour {
 		contraptionEntity.contraption.actors.remove(index);
 		contraptionEntity.contraption.actors.add(index, MutablePair.of(info, ctx));
 		if (contraptionEntity.level.isClientSide)
-			DistExecutor.unsafeRunWhenOn(Dist.CLIENT, () -> () -> invalidate(contraptionEntity.contraption));
+			contraptionEntity.contraption.deferInvalidate = true;
 	}
 
 	protected void setContraptionBlockData(AbstractContraptionEntity contraptionEntity, BlockPos pos,
@@ -32,11 +27,6 @@ public abstract class MovingInteractionBehaviour {
 		contraptionEntity.setBlock(pos, info);
 	}
 
-	@OnlyIn(Dist.CLIENT)
-	protected void invalidate(Contraption contraption) {
-		ContraptionRenderDispatcher.invalidate(contraption);
-	}
-
 	public boolean handlePlayerInteraction(Player player, InteractionHand activeHand, BlockPos localPos,
 		AbstractContraptionEntity contraptionEntity) {
 		return true;

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/render/ContraptionEntityRenderer.java

@@ -26,7 +26,7 @@ public class ContraptionEntityRenderer<C extends AbstractContraptionEntity> exte
 		double cameraZ) {
 		if (entity.getContraption() == null)
 			return false;
-		if (!entity.isAlive())
+		if (!entity.isAliveOrStale())
 			return false;
 		if (!entity.isReadyForRender())
 			return false;

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/render/ContraptionRenderInfo.java

@@ -21,24 +21,26 @@ public class ContraptionRenderInfo {
 		this.renderWorld = renderWorld;
 	}
 
-    public int getEntityId() {
+	public int getEntityId() {
-        return contraption.entity.getId();
+		return contraption.entity.getId();
-    }
+	}
 
-    public boolean isDead() {
+	public boolean isDead() {
-        return !contraption.entity.isAlive();
+		return !contraption.entity.isAliveOrStale();
-    }
+	}
 
-    public void beginFrame(BeginFrameEvent event) {
+	public void beginFrame(BeginFrameEvent event) {
 		matrices.clear();
 
 		AbstractContraptionEntity entity = contraption.entity;
 
-		visible = event.getFrustum().isVisible(entity.getBoundingBoxForCulling().inflate(2));
+		visible = event.getFrustum()
+			.isVisible(entity.getBoundingBoxForCulling()
+				.inflate(2));
 	}
 
 	public boolean isVisible() {
-		return visible && contraption.entity.isAlive() && contraption.entity.isReadyForRender();
+		return visible && contraption.entity.isAliveOrStale() && contraption.entity.isReadyForRender();
 	}
 
 	/**

src/main/java/com/simibubi/create/content/logistics/trains/entity/Carriage.java

@@ -762,7 +762,7 @@ public class Carriage {
 
 		@OnlyIn(Dist.CLIENT)
 		private void invalidate(CarriageContraptionEntity entity) {
-			ContraptionRenderDispatcher.invalidate(entity.getContraption());
+			entity.getContraption().deferInvalidate = true;
 			entity.updateRenderedPortalCutoff();
 		}