WIP tank unit type

core/src/mindustry/entities/comp/TankComp.java

@@ -0,0 +1,63 @@
+package mindustry.entities.comp;
+
+import arc.math.geom.*;
+import arc.util.*;
+import mindustry.annotations.Annotations.*;
+import mindustry.gen.*;
+import mindustry.type.*;
+import mindustry.world.blocks.environment.*;
+
+import static mindustry.Vars.*;
+
+@Component
+abstract class TankComp implements Posc, Flyingc, Hitboxc, Unitc, ElevationMovec{
+    @Import float x, y, hitSize;
+    @Import UnitType type;
+
+    transient float treadTime;
+    transient boolean walked;
+
+    @Override
+    public void update(){
+        //trigger animation only when walking manually
+        if(walked || net.client()){
+            float len = deltaLen();
+            treadTime += len;
+            walked = false;
+        }
+
+        //TODO treads should create dust, see MechComp
+    }
+
+    @Replace
+    @Override
+    public @Nullable Floor drownFloor(){
+        //tanks can only drown when all the nearby floors are deep
+        //TODO implement properly
+        if(hitSize >= 12 && canDrown()){
+            for(Point2 p : Geometry.d8){
+                Floor f = world.floorWorld(x + p.x * tilesize, y + p.y * tilesize);
+                if(!f.isDeep()){
+                    return null;
+                }
+            }
+        }
+        return canDrown() ? floorOn() : null;
+    }
+
+    @Override
+    public void moveAt(Vec2 vector, float acceleration){
+        //mark walking state when moving in a controlled manner
+        if(!vector.isZero()){
+            walked = true;
+        }
+    }
+
+    @Override
+    public void approach(Vec2 vector){
+        //mark walking state when moving in a controlled manner
+        if(!vector.isZero(0.001f)){
+            walked = true;
+        }
+    }
+}