Implemented multiblock replacement, upgrade-safe building

core/src/io/anuke/mindustry/entities/TileEntity.java

@@ -101,8 +101,8 @@ public class TileEntity extends Entity{
 				Block block = tile.block();
 
 				block.onDestroyed(tile);
-
 				world.removeBlock(tile);
+				block.afterDestroyed(tile, this);
 				remove();
 			}
 		}

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

@@ -214,6 +214,10 @@ public class Block extends BaseBlock {
 	public boolean isAccessible(){
 		return (hasItems && itemCapacity > 0);
 	}
+
+	public void afterDestroyed(Tile tile, TileEntity entity){
+
+	}
 	
 	public void onDestroyed(Tile tile){
 		float x = tile.worldx(), y = tile.worldy();

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

@@ -50,6 +50,7 @@ public class Build {
     public static void placeBlock(Team team, int x, int y, Recipe recipe, int rotation){
         Tile tile = world.tile(x, y);
         Block result = recipe.result;
+        Block previous = tile.block();
 
         //just in case
         if(tile == null) return;
@@ -57,7 +58,7 @@ public class Build {
         Block sub = Block.getByName("build" + result.size);
 
         tile.setBlock(sub, rotation);
-        tile.<BuildEntity>entity().set(recipe);
+        tile.<BuildEntity>entity().set(previous, recipe);
         tile.setTeam(team);
 
         if(result.isMultiblock()){
@@ -119,6 +120,10 @@ public class Build {
         if(tile == null || (isSpawnPoint(tile) && (type.solidifes || type.solid))) return false;
 
         if(type.isMultiblock()){
+            if(type.canReplace(tile.block()) && tile.block().size == type.size){
+                return true;
+            }
+
             int offsetx = -(type.size-1)/2;
             int offsety = -(type.size-1)/2;
             for(int dx = 0; dx < type.size; dx ++){

core/src/io/anuke/mindustry/world/blocks/types/BuildBlock.java

@@ -12,10 +12,7 @@ import io.anuke.mindustry.game.Team;
 import io.anuke.mindustry.graphics.Layer;
 import io.anuke.mindustry.graphics.Shaders;
 import io.anuke.mindustry.type.Recipe;
-import io.anuke.mindustry.world.BarType;
+import io.anuke.mindustry.world.*;
-import io.anuke.mindustry.world.Block;
-import io.anuke.mindustry.world.BlockBar;
-import io.anuke.mindustry.world.Tile;
 import io.anuke.mindustry.world.blocks.types.modules.InventoryModule;
 import io.anuke.ucore.core.Effects;
 import io.anuke.ucore.core.Graphics;
@@ -56,8 +53,23 @@ public class BuildBlock extends Block {
     }
 
     @Override
-    public void draw(Tile tile){
+    public void afterDestroyed(Tile tile, TileEntity e){
+        BuildEntity entity = (BuildEntity)e;
 
+        if(entity.previous.update || entity.previous.solid){
+            tile.setBlock(entity.previous);
+        }
+    }
+
+    @Override
+    public void draw(Tile tile){
+        BuildEntity entity = tile.entity();
+
+        if(entity.previous.update || entity.previous.solid) {
+            for (TextureRegion region : entity.previous.getBlockIcon()) {
+                Draw.rect(region, tile.drawx(), tile.drawy(), entity.recipe.result.rotate ? tile.getRotation() * 90 : 0);
+            }
+        }
     }
 
     @Override
@@ -115,6 +127,7 @@ public class BuildBlock extends Block {
         private double progress = 0;
         private double[] accumulator;
         private boolean updated;
+        private Block previous;
 
         public void addProgress(InventoryModule inventory, double amount){
             double maxProgress = amount;
@@ -147,9 +160,10 @@ public class BuildBlock extends Block {
             return (float)progress;
         }
 
-        public void set(Recipe recipe){
+        public void set(Block previous, Recipe recipe){
             updated = true;
             this.recipe = recipe;
+            this.previous = previous;
             this.accumulator = new double[recipe.requirements.length];
         }
     }