it is done

core/src/mindustry/entities/traits/SyncTrait.java

@@ -0,0 +1,48 @@
+package mindustry.entities.traits;
+
+import mindustry.net.Interpolator;
+
+import java.io.*;
+
+public interface SyncTrait extends Entity, TypeTrait{
+
+    /** Sets the position of this entity and updated the interpolator. */
+    default void setNet(float x, float y){
+        set(x, y);
+
+        if(getInterpolator() != null){
+            getInterpolator().target.set(x, y);
+            getInterpolator().last.set(x, y);
+            getInterpolator().pos.set(0, 0);
+            getInterpolator().updateSpacing = 16;
+            getInterpolator().lastUpdated = 0;
+        }
+    }
+
+    /** Interpolate entity position only. Override if you need to interpolate rotations or other values. */
+    default void interpolate(){
+        if(getInterpolator() == null){
+            throw new RuntimeException("This entity must have an interpolator to interpolate()!");
+        }
+
+        getInterpolator().update();
+
+        setX(getInterpolator().pos.x);
+        setY(getInterpolator().pos.y);
+    }
+
+    /** Return the interpolator used for smoothing the position. Optional. */
+    default Interpolator getInterpolator(){
+        return null;
+    }
+
+    /** Whether syncing is enabled for this entity; true by default. */
+    default boolean isSyncing(){
+        return true;
+    }
+
+    //Read and write sync data, usually position
+    void write(DataOutput data) throws IOException;
+
+    void read(DataInput data) throws IOException;
+}