Fixed disappearing blocks / Unit tech tree entries

core/src/mindustry/entities/EntityGroup.java

@@ -32,7 +32,7 @@ public class EntityGroup<T extends Entityc> implements Iterable<T>{
 
     /** Makes sure the next ID counter is higher than this number, so future entities cannot possibly use this ID. */
     public static void checkNextId(int id){
-        lastId = id + 1;
+        lastId = Math.max(lastId, id + 1);
     }
 
     public EntityGroup(Class<T> type, boolean spatial, boolean mapping){
@@ -47,6 +47,18 @@ public class EntityGroup<T extends Entityc> implements Iterable<T>{
         }
     }
 
+    /** @return entities with colliding IDs, or an empty array. */
+    public Seq<T> checkIDCollisions(){
+        Seq<T> out = new Seq<>();
+        IntSet ints = new IntSet();
+        each(u -> {
+            if(!ints.add(u.id())){
+                out.add(u);
+            }
+        });
+        return out;
+    }
+
     public void sort(Comparator<? super T> comp){
         array.sort(comp);
     }

core/src/mindustry/entities/Units.java

@@ -173,6 +173,22 @@ public class Units{
         return boolResult;
     }
 
+    public static boolean anyEntities(float x, float y, float width, float height, Boolf<Unit> check){
+        boolResult = false;
+
+        nearby(x, y, width, height, unit -> {
+            if(boolResult) return;
+            if(check.get(unit)){
+                unit.hitboxTile(hitrect);
+
+                if(hitrect.overlaps(aeX, aeY, aeW, aeH)){
+                    boolResult = true;
+                }
+            }
+        });
+        return boolResult;
+    }
+
     /** Returns the nearest damaged tile. */
     public static Building findDamagedTile(Team team, float x, float y){
         return indexer.getDamaged(team).min(b -> b.dst2(x, y));