Draw radar update line for mobile sensors array

OpenRA.Mods.Common/Traits/Render/RenderDetectionCircle.cs

@@ -19,14 +19,35 @@ namespace OpenRA.Mods.Common.Traits
 {
 	class RenderDetectionCircleInfo : ITraitInfo, Requires<DetectCloakedInfo>
 	{
-		public object Create(ActorInitializer init) { return new RenderDetectionCircle(init.Self); }
+		[Desc("Draw a rotating radar scanner update line, disabled by default.")]
+		public readonly bool DrawUpdateLine = false;
+
+		[Desc("WAngle the Radar update line advances per tick.")]
+		public readonly WAngle UpdateLineTick = new WAngle(-1);
+
+		[Desc("Number of trailing Radar update lines, will only draw one line if zero.")]
+		public readonly int LineTrailLength = 3;
+
+		[Desc("Color of the circle and scanner update line.")]
+		public readonly Color Color = Color.FromArgb(128, Color.LimeGreen);
+
+		[Desc("Contrast color of the circle and scanner update line.")]
+		public readonly Color ContrastColor = Color.FromArgb(96, Color.Black);
+
+		public object Create(ActorInitializer init) { return new RenderDetectionCircle(init.Self, this); }
 	}
 
-	class RenderDetectionCircle : IPostRenderSelection
+	class RenderDetectionCircle : ITick, IPostRenderSelection
 	{
+		readonly RenderDetectionCircleInfo info;
 		readonly Actor self;
+		WAngle lineAngle;
 
-		public RenderDetectionCircle(Actor self) { this.self = self; }
+		public RenderDetectionCircle(Actor self, RenderDetectionCircleInfo info)
+		{
+			this.info = info;
+			this.self = self;
+		}
 
 		public IEnumerable<IRenderable> RenderAfterWorld(WorldRenderer wr)
 		{
@@ -45,8 +66,35 @@ namespace OpenRA.Mods.Common.Traits
 				self.CenterPosition,
 				range,
 				0,
-				Color.FromArgb(128, Color.LimeGreen),
+				info.Color,
-				Color.FromArgb(96, Color.Black));
+				info.ContrastColor);
+
+			if (info.DrawUpdateLine)
+			{
+				for (var i = info.LineTrailLength; i >= 0; i--)
+				{
+					var angle = lineAngle - new WAngle(i * (info.UpdateLineTick.Angle <= 512 ? 1 : -1));
+					var length = range.Length * new WVec(angle.Cos(), angle.Sin(), 0) / 1024;
+					var alpha = info.Color.A - (info.LineTrailLength > 0 ? i * info.Color.A / info.LineTrailLength : 0);
+					yield return new BeamRenderable(
+						self.CenterPosition,
+						0,
+						length,
+						3,
+						Color.FromArgb(alpha, info.ContrastColor));
+					yield return new BeamRenderable(
+						self.CenterPosition,
+						0,
+						length,
+						1,
+						Color.FromArgb(alpha, info.Color));
+				}
+			}
+		}
+
+		public void Tick(Actor self)
+		{
+			lineAngle += info.UpdateLineTick;
 		}
 	}
 }

mods/ts/rules/shared-vehicles.yaml

@@ -148,4 +148,5 @@ LPST:
 		UpgradeMinEnabledLevel: 1
 		Range: 18c0
 	RenderDetectionCircle:
+		DrawUpdateLine: true