Initial implementation

core/src/io/anuke/mindustry/entities/type/Unit.java

@@ -7,7 +7,6 @@ import io.anuke.arc.graphics.g2d.Draw;
 import io.anuke.arc.graphics.g2d.TextureRegion;
 import io.anuke.arc.math.Mathf;
 import io.anuke.arc.math.geom.Geometry;
-import io.anuke.arc.math.geom.Rectangle;
 import io.anuke.arc.math.geom.Vector2;
 import io.anuke.arc.util.Time;
 import io.anuke.arc.util.Tmp;
@@ -15,7 +14,6 @@ import io.anuke.mindustry.content.Blocks;
 import io.anuke.mindustry.content.Fx;
 import io.anuke.mindustry.entities.Damage;
 import io.anuke.mindustry.entities.Effects;
-import io.anuke.mindustry.entities.Units;
 import io.anuke.mindustry.entities.effect.ScorchDecal;
 import io.anuke.mindustry.entities.impl.DestructibleEntity;
 import io.anuke.mindustry.entities.traits.*;
@@ -49,9 +47,10 @@ public abstract class Unit extends DestructibleEntity implements SaveTrait, Targ
     public static final float maxAbsVelocity = 127f / velocityPercision;
     public static final int noSpawner = Pos.get(-1, 1);
 
-    private static final Rectangle queryRect = new Rectangle();
     private static final Vector2 moveVector = new Vector2();
 
+    private int lastWeightTile = Pos.invalid, lastWeightDelta;
+
     public float rotation;
 
     protected final Interpolator interpolator = new Interpolator();
@@ -140,6 +139,15 @@ public abstract class Unit extends DestructibleEntity implements SaveTrait, Targ
         }
     }
 
+    @Override
+    public void removed(){
+        Tile tile = world.tile(lastWeightTile);
+
+        if(tile != null){
+            tile.weight -= Math.max(lastWeightDelta, tile.weight);
+        }
+    }
+
     @Override
     public boolean isValid(){
         return !isDead() && isAdded();
@@ -190,8 +198,8 @@ public abstract class Unit extends DestructibleEntity implements SaveTrait, Targ
     }
 
     protected void clampPosition(){
-        x = Mathf.clamp(x, tilesize, world.width() * tilesize - tilesize);
-        y = Mathf.clamp(y, tilesize, world.height() * tilesize - tilesize);
+        x = Mathf.clamp(x, 0, world.width() * tilesize - tilesize);
+        y = Mathf.clamp(y, 0, world.height() * tilesize - tilesize);
     }
 
     public void kill(){
@@ -219,17 +227,41 @@ public abstract class Unit extends DestructibleEntity implements SaveTrait, Targ
         return status.hasEffect(effect);
     }
 
-    //TODO optimize
     public void avoidOthers(float scaling){
-        hitbox(queryRect);
-        queryRect.setSize(queryRect.getWidth() * scaling);
+        if(isFlying()) return;
 
-        Units.getNearby(queryRect, t -> {
-            if(t == this || t.isFlying() != isFlying()) return;
-            float dst = dst(t);
-            moveVector.set(x, y).sub(t.getX(), t.getY()).setLength(1f * (1f - (dst / queryRect.getWidth())));
-            applyImpulse(moveVector.x, moveVector.y);
-        });
+        if(lastWeightTile != Pos.invalid){
+            Tile tile = world.tile(lastWeightTile);
+
+            if(tile != null){
+                tile.weight -= Math.min(lastWeightDelta, tile.weight);
+            }
+        }
+
+        final int rad = 1;
+
+        moveVector.setZero();
+        for(int cx = -rad; cx <= rad; cx++){
+            for(int cy = -rad; cy <= rad; cy++){
+                Tile tile = world.tileWorld(x + cx*tilesize, y + cy*tilesize);
+                if(tile == null) continue;
+                float scl = (Math.abs(cx) + Math.abs(cy) > 1 ? 1f / Mathf.sqrt2 : Math.abs(cx) + Math.abs(cy) == 1 ? 0.8f : 1f) * 0.2f;
+
+                moveVector.add(-cx * scaling * tile.weight * scl, -cy*scaling * tile.weight * scl);
+            }
+        }
+
+        applyImpulse(moveVector.x, moveVector.y);
+
+        Tile tile = world.tileWorld(x, y);
+
+        if(tile != null){
+            lastWeightDelta = Math.min((int)(mass()), 127 - tile.weight);
+            lastWeightTile = tile.pos();
+            tile.weight += lastWeightDelta;
+        }else{
+            lastWeightTile = Pos.invalid;
+        }
     }
 
     public TileEntity getClosestCore(){

core/src/io/anuke/mindustry/world/Tile.java

@@ -31,6 +31,8 @@ public class Tile implements Position, TargetTrait{
     public byte link = 0;
     /** Tile traversal cost. */
     public byte cost = 1;
+    /** Weight of [ground] units on this tile.*/
+    public byte weight = 0;
     /** Tile entity, usually null. */
     public TileEntity entity;
     public short x, y;