recoil!

OpenRa.Game/GameRules/UnitInfo.cs

@@ -49,6 +49,7 @@ namespace OpenRa.Game.GameRules
 		public readonly string[] BuiltAt = { };
 		public readonly int[] PrimaryOffset = { 0, 0 };
 		public readonly int[] SecondaryOffset = null;
+		public readonly int Recoil = 0;
 
 		public UnitInfo(string name) { Name = name; }
 

OpenRa.Game/Traits/AttackTurreted.cs

@@ -26,14 +26,28 @@ namespace OpenRa.Game.Traits
 
 		protected void DoAttack( Actor self )
 		{
-			if( self.unitInfo.Primary != null && CheckFire( self, self.unitInfo.Primary, ref primaryFireDelay, self.unitInfo.PrimaryOffset ) )
+			var rut = self.traits.GetOrDefault<RenderUnitTurreted>();
+
+			if( self.unitInfo.Primary != null && CheckFire( self, self.unitInfo.Primary, ref primaryFireDelay, 
+				self.unitInfo.PrimaryOffset ) )
 			{
 				secondaryFireDelay = Math.Max( 4, secondaryFireDelay );
+				if (rut != null) rut.primaryRecoil = 1;
 				return;
 			}
-			if( self.unitInfo.Secondary != null && CheckFire( self, self.unitInfo.Secondary, ref secondaryFireDelay, 
-				self.unitInfo.SecondaryOffset ?? self.unitInfo.PrimaryOffset) )
+
+			if (self.unitInfo.Secondary != null && CheckFire(self, self.unitInfo.Secondary, ref secondaryFireDelay,
+				self.unitInfo.SecondaryOffset ?? self.unitInfo.PrimaryOffset))
+			{
+				if (rut != null)
+				{
+					if (self.unitInfo.SecondaryOffset != null)
+						rut.secondaryRecoil = 1;
+					else
+						rut.primaryRecoil = 1;
+				}
 				return;
+			}
 		}
 
 		bool CheckFire( Actor self, string weaponName, ref int fireDelay, int[] offset )
@@ -45,7 +59,7 @@ namespace OpenRa.Game.Traits
 			fireDelay = weapon.ROF;
 
 			Game.world.Add( new Bullet( weaponName, self.Owner, self,
-				self.CenterLocation.ToInt2() + Util.GetTurretPosition( self, offset ),
+				self.CenterLocation.ToInt2() + Util.GetTurretPosition( self, offset, 0f ).ToInt2(),
 				target.CenterLocation.ToInt2() ) );
 
 			return true;

OpenRa.Game/Traits/RenderUnitTurreted.cs

@@ -10,6 +10,7 @@ namespace OpenRa.Game.Traits
 	class RenderUnitTurreted : RenderUnit
 	{
 		public Animation turretAnim;
+		public float primaryRecoil = 0.0f, secondaryRecoil = 0.0f;
 
 		public RenderUnitTurreted(Actor self)
 			: base(self)
@@ -24,16 +25,18 @@ namespace OpenRa.Game.Traits
 
 			yield return Centered(anim.Image, self.CenterLocation);
 			yield return Centered(turretAnim.Image, self.CenterLocation 
-				+ Util.GetTurretPosition(self, self.unitInfo.PrimaryOffset).ToFloat2());
+				+ Util.GetTurretPosition(self, self.unitInfo.PrimaryOffset, primaryRecoil));
 			if (self.unitInfo.SecondaryOffset != null)
 				yield return Centered(turretAnim.Image, self.CenterLocation
-					+ Util.GetTurretPosition(self, self.unitInfo.SecondaryOffset).ToFloat2());
+					+ Util.GetTurretPosition(self, self.unitInfo.SecondaryOffset, secondaryRecoil));
 		}
 
 		public override void Tick(Actor self)
 		{
 			base.Tick(self);
 			turretAnim.Tick();
+			primaryRecoil = Math.Max(0f, primaryRecoil - .2f);
+			secondaryRecoil = Math.Max(0f, secondaryRecoil - .2f);
 		}
 	}
 }

OpenRa.Game/Traits/Util.cs

@@ -54,7 +54,30 @@ namespace OpenRa.Game.Traits
 			return facing + turn;
 		}
 
-		public static int2 GetTurretPosition(Actor self, int[] offset)
+		static float2 RotateVectorByFacing(float2 v, int facing, float ecc)
+		{
+			var angle = (facing / 256f) * (2 * (float)Math.PI);
+			var sinAngle = (float)Math.Sin(angle);
+			var cosAngle = (float)Math.Cos(angle);
+
+			return new float2(
+				(cosAngle * v.X + sinAngle * v.Y),
+				ecc * (cosAngle * v.Y - sinAngle * v.X));
+		}
+
+		static float2 GetRecoil(Actor self, float recoil)
+		{
+			if (self.unitInfo.Recoil == 0) return float2.Zero;
+			var rut = self.traits.WithInterface<RenderUnitTurreted>().FirstOrDefault();
+			if (rut == null) return float2.Zero;
+
+			var facing = self.traits.Get<Turreted>().turretFacing;
+			var quantizedFacing = facing - facing % rut.turretAnim.CurrentSequence.Length;
+
+			return RotateVectorByFacing(new float2(0, recoil * self.unitInfo.Recoil), quantizedFacing, .7f);
+		}
+
+		public static float2 GetTurretPosition(Actor self, int[] offset, float recoil)
 		{
 			var ru = self.traits.WithInterface<RenderUnit>().FirstOrDefault();
 			if (ru == null) return int2.Zero;	/* things that don't have a rotating base don't need the turrets repositioned */
@@ -62,16 +85,7 @@ namespace OpenRa.Game.Traits
 			var bodyFacing = self.traits.Get<Mobile>().facing;
 			var quantizedFacing = bodyFacing - bodyFacing % ru.anim.CurrentSequence.Length;
 
-			var angle = (quantizedFacing / 256f) * (2 * (float)Math.PI);
-			var sinAngle = Math.Sin(angle);
-			var cosAngle = Math.Cos(angle);
-
-			var pos = new int2(
-				(int)(cosAngle * offset[0] + sinAngle * offset[1]),
-				(int)(cosAngle * offset[1] - sinAngle * offset[0]));
-
-			pos.Y = (int)(.7f * pos.Y);
-			return pos;
+			return (RotateVectorByFacing(new float2(offset[0], offset[1]), quantizedFacing, .7f) + GetRecoil(self, recoil));
 		}
 
 	}

units.ini

@@ -19,12 +19,15 @@ Traits=Mobile, RenderUnit
 [1TNK]
 Description=Light Tank
 Traits=Mobile, Turreted, AttackTurreted, RenderUnitTurreted
+Recoil=2;
 [2TNK]
 Description=Medium Tank
 Traits=Mobile, Turreted, AttackTurreted, RenderUnitTurreted
+Recoil=3;
 [3TNK]
 Description=Heavy Tank
 Traits=Mobile, Turreted, AttackTurreted, RenderUnitTurreted
+Recoil=3;
 [4TNK]
 Description=Mammoth Tank
 Traits=Mobile, Turreted, AttackTurreted, RenderUnitTurreted
@@ -81,6 +84,7 @@ BuiltAt=syrd
 Traits=Mobile, Turreted, RenderUnitTurreted, AttackTurreted
 PrimaryOffset=0,17
 SecondaryOffset=0,-17
+Recoil=3
 [LST]
 Description=Transport
 WaterBound=yes