Merge remote-tracking branch 'upstream/master' into client-vehicle

core/src/main/java/org/geysermc/geyser/entity/type/player/SessionPlayerEntity.java

@@ -329,4 +329,48 @@ public void setVehicleInput(Vector2f vehicleInput) {
     public void setVehicleJumpStrength(int vehicleJumpStrength) {
         this.vehicleJumpStrength = MathUtils.constrain(vehicleJumpStrength, 0, 100);
     }
+
+    private boolean isBelowVoidFloor() {
+        return position.getY() < voidFloorPosition();
+    }
+
+    public int voidFloorPosition() {
+        // The void floor is offset about 40 blocks below the bottom of the world
+        BedrockDimension bedrockDimension = session.getChunkCache().getBedrockDimension();
+        return bedrockDimension.minY() - 40;
+    }
+
+    /**
+     * This method handles teleporting the player below or above the Bedrock void floor.
+     * The Java server should never see this desync as we adjust the position that we send to it
+     *
+     * @param up in which direction to teleport - true to resync our position, or false to be
+     *           teleported below the void floor.
+     */
+    public void teleportVoidFloorFix(boolean up) {
+        // Safety to avoid double teleports
+        if ((voidPositionDesynched && !up) || (!voidPositionDesynched && up)) {
+            return;
+        }
+
+        // Work around there being a floor at the bottom of the world and teleport the player below it
+        // Moving from below to above the void floor works fine
+        Vector3f newPosition = this.getPosition();
+        if (up) {
+            newPosition = newPosition.up(4f);
+            voidPositionDesynched = false;
+        } else {
+            newPosition = newPosition.down(4f);
+            voidPositionDesynched = true;
+        }
+
+        this.setPositionManual(newPosition);
+        MovePlayerPacket movePlayerPacket = new MovePlayerPacket();
+        movePlayerPacket.setRuntimeEntityId(geyserId);
+        movePlayerPacket.setPosition(newPosition);
+        movePlayerPacket.setRotation(getBedrockRotation());
+        movePlayerPacket.setMode(MovePlayerPacket.Mode.TELEPORT);
+        movePlayerPacket.setTeleportationCause(MovePlayerPacket.TeleportationCause.BEHAVIOR);
+        session.sendUpstreamPacketImmediately(movePlayerPacket);
+    }
 }