Piecewise axis separate (#3418)

* test cases to exhibit collision issues

* add piecewise separate logic and clean up tests

* FlxObject separate logic now uses temp variable to allow updating axis separate piecewise

Author: MondayHopscotch

flixel/FlxObject.hx

@@ -159,8 +159,16 @@ class FlxObject extends FlxBasic
 	 */
 	public static function separate(object1:FlxObject, object2:FlxObject):Bool
 	{
+		var tmp1 = object1.last.copyTo();
+		var tmp2 = object2.last.copyTo();
 		final separatedX = separateX(object1, object2);
+		object1.last.x = object1.x;
+		object2.last.x = object2.x;
 		final separatedY = separateY(object1, object2);
+		object1.last.copyFrom(tmp1);
+		object2.last.copyFrom(tmp2);
+		tmp1.put();
+		tmp2.put();
 		return separatedX || separatedY;
 
 		/*

tests/unit/src/flixel/FlxObjectTest.hx

@@ -80,7 +80,7 @@ class FlxObjectTest extends FlxTest
 	}
 
 	@Test
-	function testSeprateX():Void
+	function testSeparateX():Void
 	{
 		final object1 = new FlxObject(5, 0, 10, 10);
 		object1.last.x = 10;
@@ -100,7 +100,7 @@ class FlxObjectTest extends FlxTest
 	}
 
 	@Test
-	function testSeprateY():Void
+	function testSeparateY():Void
 	{
 		final object1 = new FlxObject(0, 5, 10, 10);
 		object1.last.y = 10;
@@ -119,7 +119,23 @@ class FlxObjectTest extends FlxTest
 	}
 
 	@Test
-	function testSeprateXFromOpposite():Void
+	function testSeparateOnBothAxisNewlyOverlapping():Void
+	{
+		final object1 = new FlxObject(11, -1, 10, 10);
+		final object2 = new FlxObject(0, 10, 10, 10);
+		object2.immovable = true;
+		
+		object1.setPosition(9, 2);
+		
+		Assert.isTrue(FlxObject.separate(object1, object2));
+		// X-axis resolves first and no collision
+		Assert.areEqual(9, object1.x);
+		// Y-axis resolves second and is stopped by collision
+		Assert.areEqual(0, object1.y);
+	}
+	
+	@Test
+	function testSeparateXFromOpposite():Void
 	{
 		/*
 		 * NOTE: An odd y value on either may result in a rounding error where the second
@@ -142,7 +158,7 @@ class FlxObjectTest extends FlxTest
 	}
 
 	@Test
-	function testSeprateYFromOpposite():Void
+	function testSeparateYFromOpposite():Void
 	{
 		/*
 		 * NOTE: An odd y value on either may result in a rounding error where the second
@@ -371,7 +387,7 @@ class FlxObjectTest extends FlxTest
 	}
 
 	@Test
-	function testgetRotatedBounds()
+	function testGetRotatedBounds()
 	{
 		var expected = FlxRect.get();
 		var rect = FlxRect.get();

tests/unit/src/flixel/math/FlxRectTest.hx

@@ -34,7 +34,7 @@ class FlxRectTest extends FlxTest
 	}
 
 	@Test
-	function testgetRotatedBounds()
+	function testGetRotatedBounds()
 	{
 		var pivot = FlxPoint.get();
 		var expected = FlxRect.get();
@@ -64,7 +64,7 @@ class FlxRectTest extends FlxTest
 	}
 
 	@Test
-	function testgetRotatedBoundsSelf()
+	function testGetRotatedBoundsSelf()
 	{
 		var pivot = FlxPoint.get();
 		var expected = FlxRect.get();