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Don't forward in-flight velocity updates for arrows or fireballs #685

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Don't forward in-flight velocity updates for arrows or fireballs #685

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8095ae8
Update EntityPacketRewriter1_9.java
Term4 Jun 14, 2026
169c5d4
Update EntityPacketRewriter1_9.java
Term4 Jun 14, 2026
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13 changes: 13 additions & 0 deletions ...in/java/com/viaversion/viarewind/protocol/v1_9to1_8/rewriter/EntityPacketRewriter1_9.java
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Expand Up @@ -83,6 +83,19 @@ protected void registerPackets() {
wrapper.write(Types.ENTITY_DATA_LIST1_8, entityData);
});

// 1.8 tracks arrows and fireballs with sendVelocity=false (EntityTracker: EntityArrow/EntityFireball ->
// (.., false)), so the client predicts their trajectory locally from the spawn velocity. Modern servers send
// periodic velocity (trackDeltas) that overwrites this prediction and desyncs the client's block-collision
// raytrace (arrows visibly stick to / slide off block edges). Drop in-flight velocity for them to match 1.8.
protocol.registerClientbound(ClientboundPackets1_9.SET_ENTITY_MOTION, wrapper -> {
final int entityId = wrapper.passthrough(Types.VAR_INT);
final EntityType type = wrapper.user().getEntityTracker(Protocol1_9To1_8.class).entityType(entityId);
if (type != null && (type.isOrHasParent(EntityTypes1_9.EntityType.ARROW)
|| type.isOrHasParent(EntityTypes1_9.EntityType.HURTING_PROJECTILE))) {
wrapper.cancel();
}
});

protocol.registerClientbound(ClientboundPackets1_9.ADD_ENTITY, new PacketHandlers() {
@Override
public void register() {
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