Paper/patches/server/0544-MC-4-Fix-item-position-desync.patch
Spottedleaf 41647af74c Do not use worldgen executor for api profile completions
We cannot put blocking network I/O onto the worldgen threads,
this will crash the server if it stalls
2022-07-03 14:55:56 -07:00

50 lines
2.5 KiB
Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: BillyGalbreath <blake.galbreath@gmail.com>
Date: Tue, 8 Dec 2020 20:24:52 -0600
Subject: [PATCH] MC-4: Fix item position desync
This fixes item position desync (MC-4) by running the item coordinates
through the encode/decode methods of the packet that causes the precision
loss, which forces the server to lose the same precision as the client
keeping them in sync.
diff --git a/src/main/java/net/minecraft/network/protocol/game/VecDeltaCodec.java b/src/main/java/net/minecraft/network/protocol/game/VecDeltaCodec.java
index 3768a71491ef7836b9739bdaec7a077c523dbacd..a57957ace1a72b3308487f180a366c3879eceb21 100644
--- a/src/main/java/net/minecraft/network/protocol/game/VecDeltaCodec.java
+++ b/src/main/java/net/minecraft/network/protocol/game/VecDeltaCodec.java
@@ -8,11 +8,11 @@ public class VecDeltaCodec {
public Vec3 base = Vec3.ZERO; // Paper
private static long encode(double value) {
- return Mth.lfloor(value * 4096.0D);
+ return Mth.lfloor(value * 4096.0D); // Paper - check ItemEntity#setPosRaw on update
}
private static double decode(long value) {
- return (double)value / 4096.0D;
+ return (double)value / 4096.0D; // Paper - check ItemEntity#setPosRaw on update
}
public Vec3 decode(long x, long y, long z) {
diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index f2f91815137db868bf6968be062ef9e7b96266b8..84365010341c1f5a4ed6dcc5c4110944268ce611 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -3893,6 +3893,16 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource {
}
public final void setPosRaw(double x, double y, double z, boolean forceBoundingBoxUpdate) {
// Paper end
+ // Paper start - fix MC-4
+ if (this instanceof ItemEntity) {
+ if (io.papermc.paper.configuration.GlobalConfiguration.get().misc.fixEntityPositionDesync) {
+ // encode/decode from ClientboundMoveEntityPacket
+ x = Mth.lfloor(x * 4096.0D) * (1 / 4096.0D);
+ y = Mth.lfloor(y * 4096.0D) * (1 / 4096.0D);
+ z = Mth.lfloor(z * 4096.0D) * (1 / 4096.0D);
+ }
+ }
+ // Paper end - fix MC-4
if (this.position.x != x || this.position.y != y || this.position.z != z) {
this.position = new Vec3(x, y, z);
int i = Mth.floor(x);