Implement rotation collision check.

Assets/Scripts/tetrominoUserControl.cs

@@ -45,13 +45,15 @@ public class tetrominoUserControl : MonoBehaviour
 
         if (Input.GetButtonDown("tetrisRotateLeft") && activeTetromino != null)
         {
-            activeTetromino.gameObject.transform.Rotate(0,0,90,Space.World);
+            rotateWithChecks(90);
+            // activeTetromino.gameObject.transform.Rotate(0,0,90,Space.World);
             GetComponent<AudioSource>().Play();
         }
         
         if (Input.GetButtonDown("tetrisRotateRight") && activeTetromino != null)
         {
-            activeTetromino.gameObject.transform.Rotate(0,0,-90,Space.World);
+            rotateWithChecks(90);
+            // activeTetromino.gameObject.transform.Rotate(0,0,-90,Space.World);
             GetComponent<AudioSource>().Play();
         }
 
@@ -94,4 +96,41 @@ public class tetrominoUserControl : MonoBehaviour
             return false;
         }
     }
+
+    public void rotateWithChecks(int degrees)
+    {
+        bool wouldCollide = false;
+        Collider2D[] results = new Collider2D[10];
+        
+        //Perform the rotation (will undo later if there's a collision).
+        activeTetromino.gameObject.transform.Rotate(0,0,degrees,Space.World);
+
+        foreach (Transform child in activeTetromino.transform)
+        {
+            //Store any overlapping colliders in the results array.
+            child.GetComponent<BoxCollider2D>().OverlapCollider(new ContactFilter2D().NoFilter(), results);
+            //If there are collisions...
+            if (results.Length != 0)
+            {
+                foreach (Collider2D a in results)
+                {
+                    //and IF they aren't an extra null item in the array...
+                    if (a != null)
+                    {
+                        //Only act if the overlap is not with another part of this tetromino.
+                        if (a.gameObject.transform.parent != child.parent)
+                        {
+                            Debug.Log("Collision detected with " + a.gameObject.name);
+                            wouldCollide = true;
+                        }
+                    }
+                }
+            }
+        }
+        //If we collided, undo the rotation.
+        if (wouldCollide == true)
+        {
+            activeTetromino.gameObject.transform.Rotate(0,0,degrees * -1,Space.World);
+        }
+    }
 }