Make Bullet projectile extensible

OpenRA.Mods.Common/Projectiles/Bullet.cs

@@ -134,14 +134,14 @@ namespace OpenRA.Mods.Common.Projectiles
 		[Desc("The alpha value [from 0 to 255] of color at the contrail end.")]
 		public readonly int ContrailEndColorAlpha = 0;
 
-		public IProjectile Create(ProjectileArgs args) { return new Bullet(this, args); }
+		public virtual IProjectile Create(ProjectileArgs args) { return new Bullet(this, args); }
 	}
 
 	public class Bullet : IProjectile, ISync
 	{
 		readonly BulletInfo info;
-		readonly ProjectileArgs args;
+		protected readonly ProjectileArgs Args;
-		readonly Animation anim;
+		protected readonly Animation Animation;
 		readonly WAngle facing;
 		readonly WAngle angle;
 		readonly WDist speed;
@@ -153,16 +153,18 @@ namespace OpenRA.Mods.Common.Projectiles
 		readonly ContrailRenderable contrail;
 
 		[Sync]
-		WPos pos, lastPos, target, source;
+		protected WPos pos, lastPos, target, source;
 
 		int length;
 		int ticks, smokeTicks;
 		int remainingBounces;
 
+		protected bool FlightLengthReached => ticks >= length;
+
 		public Bullet(BulletInfo info, ProjectileArgs args)
 		{
 			this.info = info;
-			this.args = args;
+			Args = args;
 			pos = args.Source;
 			source = args.Source;
 
@@ -193,8 +195,8 @@ namespace OpenRA.Mods.Common.Projectiles
 
 			if (!string.IsNullOrEmpty(info.Image))
 			{
-				anim = new Animation(world, info.Image, new Func<WAngle>(GetEffectiveFacing));
+				Animation = new Animation(world, info.Image, new Func<WAngle>(GetEffectiveFacing));
-				anim.PlayRepeating(info.Sequences.Random(world.SharedRandom));
+				Animation.PlayRepeating(info.Sequences.Random(world.SharedRandom));
 			}
 
 			if (info.ContrailLength > 0)
@@ -230,21 +232,26 @@ namespace OpenRA.Mods.Common.Projectiles
 			return new WAngle(effective);
 		}
 
-		public void Tick(World world)
+		public virtual void Tick(World world)
 		{
-			anim?.Tick();
+			Animation?.Tick();
 
 			lastPos = pos;
 			pos = WPos.LerpQuadratic(source, target, angle, ticks, length);
 
 			if (ShouldExplode(world))
+			{
+				if (info.ContrailLength > 0)
+					world.AddFrameEndTask(w => w.Add(new ContrailFader(pos, contrail)));
+
 				Explode(world);
+			}
 		}
 
 		bool ShouldExplode(World world)
 		{
 			// Check for walls or other blocking obstacles
-			if (info.Blockable && BlocksProjectiles.AnyBlockingActorsBetween(world, args.SourceActor.Owner, lastPos, pos, info.Width, out var blockedPos))
+			if (info.Blockable && BlocksProjectiles.AnyBlockingActorsBetween(world, Args.SourceActor.Owner, lastPos, pos, info.Width, out var blockedPos))
 			{
 				pos = blockedPos;
 				return true;
@@ -274,7 +281,7 @@ namespace OpenRA.Mods.Common.Projectiles
 				if (info.InvalidBounceTerrain.Contains(world.Map.GetTerrainInfo(cell).Type))
 					return true;
 
-				if (AnyValidTargetsInRadius(world, pos, info.Width, args.SourceActor, true))
+				if (AnyValidTargetsInRadius(world, pos, info.Width, Args.SourceActor, true))
 					return true;
 
 				target += (pos - source) * info.BounceRangeModifier / 100;
@@ -297,26 +304,35 @@ namespace OpenRA.Mods.Common.Projectiles
 				return true;
 
 			// After first bounce, check for targets each tick
-			if (remainingBounces < info.BounceCount && AnyValidTargetsInRadius(world, pos, info.Width, args.SourceActor, true))
+			if (remainingBounces < info.BounceCount && AnyValidTargetsInRadius(world, pos, info.Width, Args.SourceActor, true))
 				return true;
 
 			return false;
 		}
 
-		public IEnumerable<IRenderable> Render(WorldRenderer wr)
+		public virtual IEnumerable<IRenderable> Render(WorldRenderer wr)
 		{
 			if (info.ContrailLength > 0)
 				yield return contrail;
 
-			if (anim == null || ticks >= length)
+			if (FlightLengthReached)
 				yield break;
 
-			var world = args.SourceActor.World;
+			foreach (var r in RenderAnimation(wr))
+				yield return r;
+		}
+
+		protected IEnumerable<IRenderable> RenderAnimation(WorldRenderer wr)
+		{
+			if (Animation == null)
+				yield break;
+
+			var world = Args.SourceActor.World;
 			if (!world.FogObscures(pos))
 			{
 				var paletteName = info.Palette;
 				if (paletteName != null && info.IsPlayerPalette)
-					paletteName += args.SourceActor.Owner.InternalName;
+					paletteName += Args.SourceActor.Owner.InternalName;
 
 				var palette = wr.Palette(paletteName);
 
@@ -324,31 +340,28 @@ namespace OpenRA.Mods.Common.Projectiles
 				{
 					var dat = world.Map.DistanceAboveTerrain(pos);
 					var shadowPos = pos - new WVec(0, 0, dat.Length);
-					foreach (var r in anim.Render(shadowPos, palette))
+					foreach (var r in Animation.Render(shadowPos, palette))
 						yield return ((IModifyableRenderable)r)
 							.WithTint(shadowColor, ((IModifyableRenderable)r).TintModifiers | TintModifiers.ReplaceColor)
 							.WithAlpha(shadowAlpha);
 				}
 
-				foreach (var r in anim.Render(pos, palette))
+				foreach (var r in Animation.Render(pos, palette))
 					yield return r;
 			}
 		}
 
-		void Explode(World world)
+		protected virtual void Explode(World world)
 		{
-			if (info.ContrailLength > 0)
-				world.AddFrameEndTask(w => w.Add(new ContrailFader(pos, contrail)));
-
 			world.AddFrameEndTask(w => w.Remove(this));
 
-			var warheadArgs = new WarheadArgs(args)
+			var warheadArgs = new WarheadArgs(Args)
 			{
-				ImpactOrientation = new WRot(WAngle.Zero, Util.GetVerticalAngle(lastPos, pos), args.Facing),
+				ImpactOrientation = new WRot(WAngle.Zero, Util.GetVerticalAngle(lastPos, pos), Args.Facing),
 				ImpactPosition = pos,
 			};
 
-			args.Weapon.Impact(Target.FromPos(pos), warheadArgs);
+			Args.Weapon.Impact(Target.FromPos(pos), warheadArgs);
 		}
 
 		bool AnyValidTargetsInRadius(World world, WPos pos, WDist radius, Actor firedBy, bool checkTargetType)