Fix and rewrite contrails. Closes #3457.

OpenRA.Game/Graphics/ContrailRenderable.cs

@@ -0,0 +1,105 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2013 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation. For more information,
+ * see COPYING.
+ */
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Drawing;
+
+namespace OpenRA.Graphics
+{
+	public struct ContrailRenderable : IRenderable
+	{
+		readonly World world;
+
+		// Store trail positions in a circular buffer
+		readonly WPos[] trail;
+		int next;
+		int length;
+		int skip;
+
+		readonly Color color;
+		readonly int zOffset;
+
+		public ContrailRenderable(World world, Color color, int length, int skip, int zOffset)
+			: this(world, new WPos[length], 0, 0, skip, color, zOffset) {}
+
+		ContrailRenderable(World world, WPos[] trail, int next, int length, int skip, Color color, int zOffset)
+		{
+			this.world = world;
+			this.trail = trail;
+			this.next = next;
+			this.length = length;
+			this.skip = skip;
+			this.color = color;
+			this.zOffset = zOffset;
+		}
+
+		public WPos Pos { get { return trail[idx(next-1)]; } }
+		public float Scale { get { return 1f; } }
+		public PaletteReference Palette { get { return null; } }
+		public int ZOffset { get { return zOffset; } }
+
+		public IRenderable WithScale(float newScale) { return new ContrailRenderable(world, (WPos[])trail.Clone(), next, length, skip, color, zOffset); }
+		public IRenderable WithPalette(PaletteReference newPalette) { return new ContrailRenderable(world, (WPos[])trail.Clone(), next, length, skip, color, zOffset); }
+		public IRenderable WithZOffset(int newOffset) { return new ContrailRenderable(world, (WPos[])trail.Clone(), next, length, skip, color, newOffset); }
+		public IRenderable WithPos(WPos pos) { return new ContrailRenderable(world, (WPos[])trail.Clone(), next, length, skip, color, zOffset); }
+
+		public void BeforeRender(WorldRenderer wr) {}
+		public void Render(WorldRenderer wr)
+		{
+			// Need at least 4 points to smooth the contrail over
+			if (length - skip < 4 )
+				return;
+
+			// Start of the first line segment is the tail of the list - don't smooth it.
+			var curPos = trail[idx(next - skip - 1)];
+			var curCell = new CPos(curPos);
+			var curColor = color;
+			for (var i = 0; i < length - skip - 4; i++)
+			{
+				var j = next - skip - i - 2;
+				var nextPos = WPos.Average(trail[idx(j)], trail[idx(j-1)], trail[idx(j-2)], trail[idx(j-3)]);
+				var nextCell = new CPos(nextPos);
+				var nextColor = Exts.ColorLerp(i * 1f / (length - 4), color, Color.Transparent);
+
+				if (!world.FogObscures(curCell) && !world.FogObscures(nextCell))
+					Game.Renderer.WorldLineRenderer.DrawLine(wr.ScreenPosition(curPos), wr.ScreenPosition(nextPos), curColor, nextColor);
+
+				curPos = nextPos;
+				curCell = nextCell;
+				curColor = nextColor;
+			}
+		}
+
+		public void RenderDebugGeometry(WorldRenderer wr) {}
+
+		// Array index modulo length
+		int idx(int i)
+		{
+			var j = i % trail.Length;
+			return j < 0 ? j + trail.Length : j;
+		}
+
+		public void Update(WPos pos)
+		{
+			trail[next] = pos;
+			next = idx(next+1);
+
+			if (length < trail.Length)
+				length++;
+		}
+
+		public static Color ChooseColor(Actor self)
+		{
+			var ownerColor = Color.FromArgb(255, self.Owner.Color.RGB);
+			return Exts.ColorLerp(0.5f, ownerColor, Color.White);
+		}
+	}
+}

OpenRA.Game/OpenRA.Game.csproj

@@ -235,6 +235,7 @@
     <Compile Include="Graphics\VoxelRenderable.cs" />
     <Compile Include="Graphics\TextRenderable.cs" />
     <Compile Include="Graphics\BeamRenderable.cs" />
+    <Compile Include="Graphics\ContrailRenderable.cs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\OpenRA.FileFormats\OpenRA.FileFormats.csproj">

OpenRA.Mods.RA/Effects/Bullet.cs

@@ -51,7 +51,7 @@ namespace OpenRA.Mods.RA.Effects
 		Animation anim;
 
 		const int BaseBulletSpeed = 100;		/* pixels / 40ms frame */
-		ContrailHistory Trail;
+		ContrailRenderable Trail;
 
 		public Bullet(BulletInfo info, ProjectileArgs args)
 		{
@@ -73,9 +73,8 @@ namespace OpenRA.Mods.RA.Effects
 
 			if (Info.ContrailLength > 0)
 			{
-				Trail = new ContrailHistory(Info.ContrailLength,
+				var color = Info.ContrailUsePlayerColor ? ContrailRenderable.ChooseColor(args.firedBy) : Info.ContrailColor;
-					Info.ContrailUsePlayerColor ? ContrailHistory.ChooseColor(args.firedBy) : Info.ContrailColor,
+				Trail = new ContrailRenderable(args.firedBy.World, color, Info.ContrailLength, Info.ContrailDelay, 0);
-					Info.ContrailDelay);
 			}
 		}
 
@@ -127,10 +126,10 @@ namespace OpenRA.Mods.RA.Effects
 					ticksToNextSmoke = Info.TrailInterval;
 				}
 
-				if (Trail != null)
+				if (Info.ContrailLength > 0)
 				{
 					var alt = (Info.High || Info.Angle > 0) ? GetAltitude() : 0;
-					Trail.Tick(new PPos((int)pos.X, (int)pos.Y).ToWPos((int)alt));
+					Trail.Update(new PPos((int)pos.X, (int)pos.Y).ToWPos((int)alt));
 				}
 			}
 
@@ -153,6 +152,9 @@ namespace OpenRA.Mods.RA.Effects
 
 		public IEnumerable<IRenderable> Render(WorldRenderer wr)
 		{
+			if (Info.ContrailLength > 0)
+				yield return Trail;
+
 			if (anim != null)
 			{
 				var at = (float)t / TotalTime();
@@ -177,9 +179,6 @@ namespace OpenRA.Mods.RA.Effects
 							wr.Palette(Args.weapon.Underwater ? "shadow" : "effect"), (int)pos.Y);
 				}
 			}
-
-			if (Trail != null)
-				Trail.Render(wr, Args.firedBy);
 		}
 
 		void Explode( World world )

OpenRA.Mods.RA/Effects/Contrail.cs

@@ -28,17 +28,18 @@ namespace OpenRA.Mods.RA
 		public object Create(ActorInitializer init) { return new Contrail(init.self, this); }
 	}
 
-	class Contrail : ITick, IPostRender
+	class Contrail : ITick, IRender
 	{
 		ContrailInfo info;
-		ContrailHistory history;
+		ContrailRenderable trail;
 		IBodyOrientation body;
 
 		public Contrail(Actor self, ContrailInfo info)
 		{
 			this.info = info;
-			history = new ContrailHistory(info.TrailLength,
+
-				info.UsePlayerColor ? ContrailHistory.ChooseColor(self) : info.Color);
+			var color = info.UsePlayerColor ? ContrailRenderable.ChooseColor(self) : info.Color;
+			trail = new ContrailRenderable(self.World, color, info.TrailLength, 0, 0);
 
 			body = self.Trait<IBodyOrientation>();
 		}
@@ -46,62 +47,12 @@ namespace OpenRA.Mods.RA
 		public void Tick(Actor self)
 		{
 			var local = info.Offset.Rotate(body.QuantizeOrientation(self, self.Orientation));
-			history.Tick(self.CenterPosition + body.LocalToWorld(local));
+			trail.Update(self.CenterPosition + body.LocalToWorld(local));
 		}
 
-		public void RenderAfterWorld(WorldRenderer wr, Actor self) { history.Render(wr, self); }
+		public IEnumerable<IRenderable> Render(Actor self, WorldRenderer wr)
-	}
-
-	class ContrailHistory
-	{
-		List<WPos> positions = new List<WPos>();
-		readonly int TrailLength;
-		readonly Color Color;
-		readonly int StartSkip;
-
-		public static Color ChooseColor(Actor self)
 		{
-			var ownerColor = Color.FromArgb(255, self.Owner.Color.RGB);
+			yield return trail;
-			return Exts.ColorLerp(0.5f, ownerColor, Color.White);
-		}
-
-		public ContrailHistory(int trailLength, Color color)
-			: this(trailLength, color, 0) { }
-
-		public ContrailHistory(int trailLength, Color color, int startSkip)
-		{
-			this.TrailLength = trailLength;
-			this.Color = color;
-			this.StartSkip = startSkip;
-		}
-
-		public void Tick(WPos currentPos)
-		{
-			positions.Add(currentPos);
-			if (positions.Count >= TrailLength)
-				positions.RemoveAt(0);
-		}
-
-		public void Render(WorldRenderer wr, Actor self)
-		{
-			Color trailStart = Color;
-			Color trailEnd = Color.FromArgb(trailStart.A - 255 / TrailLength, trailStart.R, trailStart.G, trailStart.B);
-
-			for (int i = positions.Count - 1 - StartSkip; i >= 4; --i)
-			{
-				// World positions
-				var conPos = WPos.Average(positions[i], positions[i-1], positions[i-2], positions[i-3]);
-				var nextPos = WPos.Average(positions[i-1], positions[i-2], positions[i-3], positions[i-4]);
-
-				if (!self.World.FogObscures(new CPos(conPos)) &&
-				    !self.World.FogObscures(new CPos(nextPos)))
-				{
-					Game.Renderer.WorldLineRenderer.DrawLine(wr.ScreenPosition(conPos), wr.ScreenPosition(nextPos), trailStart, trailEnd);
-
-					trailStart = trailEnd;
-					trailEnd = Color.FromArgb(trailStart.A - 255 / positions.Count, trailStart.R, trailStart.G, trailStart.B);
-				}
-			}
 		}
 	}
 }

OpenRA.Mods.RA/Effects/Missile.cs

@@ -59,7 +59,7 @@ namespace OpenRA.Mods.RA.Effects
 		int Facing;
 		int t;
 		int Altitude;
-		ContrailHistory Trail;
+		ContrailRenderable Trail;
 
 		public Missile(MissileInfo info, ProjectileArgs args)
 		{
@@ -81,9 +81,8 @@ namespace OpenRA.Mods.RA.Effects
 
 			if (Info.ContrailLength > 0)
 			{
-				Trail = new ContrailHistory(Info.ContrailLength,
+				var color = Info.ContrailUsePlayerColor ? ContrailRenderable.ChooseColor(args.firedBy) : Info.ContrailColor;
-					Info.ContrailUsePlayerColor ? ContrailHistory.ChooseColor(args.firedBy) : Info.ContrailColor,
+				Trail = new ContrailRenderable(args.firedBy.World, color, Info.ContrailLength, Info.ContrailDelay, 0);
-					Info.ContrailDelay);
 			}
 		}
 
@@ -162,8 +161,8 @@ namespace OpenRA.Mods.RA.Effects
 					Explode(world);
 			}
 
-			if (Trail != null)
+			if (Info.ContrailLength > 0)
-				Trail.Tick(PxPosition.ToWPos(Altitude));
+				Trail.Update(PxPosition.ToWPos(Altitude));
 		}
 
 		void Explode(World world)
@@ -176,12 +175,12 @@ namespace OpenRA.Mods.RA.Effects
 
 		public IEnumerable<IRenderable> Render(WorldRenderer wr)
 		{
+			if (Info.ContrailLength > 0)
+				yield return Trail;
+
 			if (!Args.firedBy.World.FogObscures(PxPosition.ToCPos()))
 				yield return new SpriteRenderable(anim.Image, PxPosition.ToFloat2() - new float2(0, Altitude),
 				                                  wr.Palette(Args.weapon.Underwater ? "shadow" : "effect"), PxPosition.Y);
-
-			if (Trail != null)
-				Trail.Render(wr, Args.firedBy);
 		}
 	}
 }