Move ContrailRenderable into Mods.RA.

OpenRA.Mods.RA/Graphics/ContrailRenderable.cs

@@ -0,0 +1,120 @@
+#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.Drawing;
+using System.Linq;
+using OpenRA.Graphics;
+
+namespace OpenRA.Mods.RA.Graphics
+{
+	public struct ContrailRenderable : IRenderable
+	{
+		public int Length { get { return trail.Length; } }
+
+		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 bool IsDecoration { get { return true; } }
+
+		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 OffsetBy(WVec vec) { return new ContrailRenderable(world, trail.Select(pos => pos + vec).ToArray(), next, length, skip, color, zOffset); }
+		public IRenderable AsDecoration() { return this; }
+
+		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;
+
+			var wlr = Game.Renderer.WorldLineRenderer;
+			var oldWidth = wlr.LineWidth;
+			wlr.LineWidth = wr.Viewport.Zoom;
+
+			// 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 = wr.world.Map.CellContaining(curPos);
+			var curColor = color;
+			for (var i = 0; i < length - skip - 4; i++)
+			{
+				var j = next - skip - i - 2;
+				var nextPos = Average(trail[idx(j)], trail[idx(j-1)], trail[idx(j-2)], trail[idx(j-3)]);
+				var nextCell = wr.world.Map.CellContaining(nextPos);
+				var nextColor = Exts.ColorLerp(i * 1f / (length - 4), color, Color.Transparent);
+
+				if (!world.FogObscures(curCell) && !world.FogObscures(nextCell))
+					wlr.DrawLine(wr.ScreenPosition(curPos), wr.ScreenPosition(nextPos), curColor, nextColor);
+
+				curPos = nextPos;
+				curCell = nextCell;
+				curColor = nextColor;
+			}
+
+			wlr.LineWidth = oldWidth;
+		}
+
+		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;
+		}
+
+		static WPos Average(params WPos[] list)
+		{
+			return list.Average();
+		}
+
+		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);
+		}
+	}
+}