Add smooth shellmap movement

OpenRA.Game/Graphics/Viewport.cs

@@ -71,6 +71,8 @@ namespace OpenRA.Graphics
 		float defaultScale;
 		bool overrideUserScale;
 
+		public Func<float2> ViewportCenterProvider;
+
 		public float Zoom
 		{
 			get => zoom;
@@ -177,6 +179,9 @@ namespace OpenRA.Graphics
 		{
 			if (lastViewportDistance != graphicSettings.ViewportDistance)
 				UpdateViewportZooms();
+
+			if (ViewportCenterProvider != null)
+				Center(ViewportCenterProvider());
 		}
 
 		static float CalculateMinimumZoom(float minHeight, float maxHeight)

OpenRA.Mods.Common/Traits/World/CameraMover.cs

@@ -0,0 +1,65 @@
+#region Copyright & License Information
+/*
+ * Copyright (c) The OpenRA Developers and Contributors
+ * 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, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System;
+using OpenRA.Graphics;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Traits
+{
+	[TraitLocation(SystemActors.World)]
+	[Desc("Moves the camera in an oval pattern around its starting position.")]
+	sealed class CameraOvalMoverInfo : TraitInfo
+	{
+		[Desc("Starting angle in degrees.")]
+		public int StartAngle = 45;
+
+		[Desc("How fast the camera moves around the oval.")]
+		public float DegreesPerSecond = 3f;
+
+		[Desc("The X and Y radius of the oval path. Z is unused.")]
+		public WVec OvalRadius = new(19200, 20480, 0);
+
+		public override object Create(ActorInitializer init) { return new CameraOvalMover(this); }
+	}
+
+	sealed class CameraOvalMover : IWorldLoaded
+	{
+		readonly CameraOvalMoverInfo info;
+		public CameraOvalMover(CameraOvalMoverInfo info)
+		{
+			this.info = info;
+		}
+
+		public void WorldLoaded(World world, WorldRenderer wr)
+		{
+			var vo = wr.Viewport.CenterPosition;
+			var viewportOrigin = new float2(vo.X, vo.Y);
+
+			float angle = info.StartAngle;
+			long lastTime = 0;
+			wr.Viewport.ViewportCenterProvider = () =>
+			{
+				var currentTime = Game.RunTime;
+				var dt = currentTime - lastTime;
+				lastTime = currentTime;
+
+				// Prevent large jumps when the game is paused or the framerate is very low.
+				const float MaxStep = 0.25f;
+				angle += Math.Min(dt / 1000.0f * info.DegreesPerSecond, MaxStep);
+
+				var rad = angle * (Math.PI / 180);
+				var offset = new float2((float)(info.OvalRadius.X * Math.Sin(rad)), (float)(info.OvalRadius.Y * Math.Cos(rad)));
+				return viewportOrigin + offset;
+			};
+		}
+	}
+}

mods/d2k/maps/shellmap/d2k-shellmap.lua

@@ -139,18 +139,6 @@ InitializeHarvester = function(harvester)
 	harvester.FindResources()
 end
 
-Ticks = 0
-Speed = 5
-
-Tick = function()
-	Ticks = Ticks + 1
-
-	if Ticks > 1 or not Map.IsPausedShellmap then
-		local t = (Ticks + 45) % (360 * Speed) * (math.pi / 180) / Speed;
-		Camera.Position = ViewportOrigin + WVec.New(19200 * math.sin(t), 28800 * math.cos(t), 0)
-	end
-end
-
 WorldLoaded = function()
 	Atreides = Player.GetPlayer("Atreides")
 	Harkonnen = Player.GetPlayer("Harkonnen")
@@ -162,8 +150,6 @@ WorldLoaded = function()
 	Reinforcements.Reinforce(Atreides, { "carryall" }, { atr_carry_2.Location })
 	Reinforcements.Reinforce(Atreides, { "carryall" }, { atr_carry_3.Location })
 
-	ViewportOrigin = Camera.Position
-
 	Utils.Do(Utils.Take(4, Upgrades), function(upgrade)
 		atr_cyard.Produce(upgrade)
 		har_cyard.Produce(upgrade)
@@ -201,6 +187,4 @@ WorldLoaded = function()
 		Produce(Corrino, CorrinoTankTypes)
 		Produce(Corrino, CorrinoStarportTypes)
 	end)
-
-	Tick()
 end

mods/d2k/maps/shellmap/rules.yaml

@@ -19,6 +19,8 @@ World:
 		DisableWorldSounds: true
 	LuaScript:
 		Scripts: utils.lua, d2k-shellmap.lua
+	CameraOvalMover:
+		OvalRadius: 19200, 28800, 0
 
 ^Palettes:
 	-MenuPostProcessEffect:

mods/ra/maps/desert-shellmap/desert-shellmap.lua

@@ -170,20 +170,9 @@ ChronoshiftAlliedUnits = function()
 	Trigger.AfterDelay(DateTime.Seconds(60), ChronoshiftAlliedUnits)
 end
 
-Ticks = 0
-Speed = 5
-
-Tick = function()
-	Ticks = Ticks + 1
-
-	local t = (Ticks + 45) % (360 * Speed) * (math.pi / 180) / Speed;
-	Camera.Position = ViewportOrigin + WVec.New(19200 * math.sin(t), 20480 * math.cos(t), 0)
-end
-
 WorldLoaded = function()
 	Allies = Player.GetPlayer("Allies")
 	Soviets = Player.GetPlayer("Soviets")
-	ViewportOrigin = Camera.Position
 
 	SetupAlliedUnits()
 	SetupFactories()

mods/ra/maps/desert-shellmap/rules.yaml

@@ -20,6 +20,7 @@ World:
 	LuaScript:
 		Scripts: desert-shellmap.lua
 	-StartGameNotification:
+	CameraOvalMover:
 
 ^Palettes:
 	-MenuPostProcessEffect: