Add smooth scrolling

OpenRA.Game/Game.cs

@@ -724,7 +724,7 @@ namespace OpenRA
 				// Use worldRenderer.World instead of OrderManager.World to avoid a rendering mismatch while processing orders
 				if (worldRenderer != null && !worldRenderer.World.IsLoadingGameSave)
 				{
-					Renderer.BeginWorld(worldRenderer.Viewport.Rectangle);
+					Renderer.BeginWorld(worldRenderer.Viewport.CenterLocation, worldRenderer.Viewport.ViewportSize);
 					Sound.SetListenerPosition(worldRenderer.Viewport.CenterPosition);
 					using (new PerfSample("render_world"))
 						worldRenderer.Draw();

OpenRA.Game/Graphics/Viewport.cs

@@ -49,14 +49,13 @@ namespace OpenRA.Graphics
 		readonly Size tileSize;
 
 		// Viewport geometry (world-px)
-		public int2 CenterLocation { get; private set; }
+		public float2 CenterLocation { get; private set; }
 
-		public WPos CenterPosition => worldRenderer.ProjectedPosition(CenterLocation);
+		public WPos CenterPosition => worldRenderer.ProjectedPosition(CenterLocation.ToInt2());
 
-		public Rectangle Rectangle => new(TopLeft, new Size(viewportSize.X, viewportSize.Y));
-		public int2 TopLeft => CenterLocation - viewportSize / 2;
-		public int2 BottomRight => CenterLocation + viewportSize / 2;
-		int2 viewportSize;
+		public int2 TopLeft => CenterLocation.ToInt2() - ViewportSize.ToInt2() / 2;
+		public int2 BottomRight => CenterLocation.ToInt2() + ViewportSize.ToInt2() / 2;
+		public Size ViewportSize { get; private set; }
 		ProjectedCellRegion cells;
 		bool cellsDirty = true;
 
@@ -79,7 +78,7 @@ namespace OpenRA.Graphics
 			private set
 			{
 				zoom = value;
-				viewportSize = (1f / zoom * new float2(Game.Renderer.NativeResolution)).ToInt2();
+				ViewportSize = Size.FromInt2((1f / zoom * new float2(Game.Renderer.NativeResolution)).ToInt2());
 				cellsDirty = true;
 				allCellsDirty = true;
 			}
@@ -341,7 +340,7 @@ namespace OpenRA.Graphics
 		public void Scroll(float2 delta, bool ignoreBorders)
 		{
 			// Convert scroll delta from world-px to viewport-px
-			CenterLocation += (1f / Zoom * delta).ToInt2();
+			CenterLocation += 1f / Zoom * delta;
 			cellsDirty = true;
 			allCellsDirty = true;
 

OpenRA.Game/Primitives/float2.cs

@@ -93,6 +93,21 @@ namespace OpenRA
 		public static float2 Max(float2 a, float2 b) { return new float2(Math.Max(a.X, b.X), Math.Max(a.Y, b.Y)); }
 		public static float2 Min(float2 a, float2 b) { return new float2(Math.Min(a.X, b.X), Math.Min(a.Y, b.Y)); }
 
+		public float2 Clamp(Rectangle r)
+		{
+			var x = X;
+			var y = Y;
+			if (r.Left > X)
+				x = r.Left;
+			if (r.Top > Y)
+				y = r.Top;
+			if (r.Right < X)
+				x = r.Right;
+			if (r.Bottom < Y)
+				y = r.Bottom;
+			return new float2(x, y);
+		}
+
 		public float LengthSquared => X * X + Y * Y;
 		public float Length => (float)Math.Sqrt(LengthSquared);
 	}

OpenRA.Game/Renderer.cs

@@ -77,7 +77,8 @@ namespace OpenRA
 
 		Size lastBufferSize = new(-1, -1);
 
-		Rectangle lastWorldViewport = Rectangle.Empty;
+		Rectangle lastWorldViewport;
+		float2 lastViewportLocation;
 		ITexture currentPaletteTexture;
 		int currentPaletteHeight = 0;
 		IBatchRenderer currentBatchRenderer;
@@ -233,7 +234,7 @@ namespace OpenRA
 			lastMaximumViewportSize = size;
 		}
 
-		public void BeginWorld(Rectangle worldViewport)
+		public void BeginWorld(float2 viewportLocation, Size viewportSize)
 		{
 			if (renderType != RenderType.None)
 				throw new InvalidOperationException($"BeginWorld called with renderType = {renderType}, expected RenderType.None.");
@@ -243,28 +244,34 @@ namespace OpenRA
 			if (worldSheet == null)
 				throw new InvalidOperationException("BeginWorld called before SetMaximumViewportSize has been set.");
 
-			if (worldSprite == null || worldViewport.Size != lastWorldViewportSize)
+			var centerLocation = viewportLocation.ToInt2();
+			if (worldSprite == null || viewportSize != lastWorldViewportSize || viewportLocation != lastViewportLocation)
 			{
+				lastViewportLocation = viewportLocation;
+				lastWorldViewportSize = viewportSize;
+
 				// Downscale world rendering if needed to fit within the framebuffer
-				var vw = worldViewport.Size.Width;
-				var vh = worldViewport.Size.Height;
+				var vw = viewportSize.Width;
+				var vh = viewportSize.Height;
 				var bw = worldSheet.Size.Width;
 				var bh = worldSheet.Size.Height;
 				WorldDownscaleFactor = 1;
 				while (vw / WorldDownscaleFactor > bw || vh / WorldDownscaleFactor > bh)
 					WorldDownscaleFactor++;
 
-				var s = new Size(vw / WorldDownscaleFactor, vh / WorldDownscaleFactor);
-				worldSprite = new Sprite(worldSheet, new Rectangle(int2.Zero, s), TextureChannel.RGBA);
-				lastWorldViewportSize = worldViewport.Size;
+				// We need to add 1 to scroll in order to handle interpixel 0-0.99 fractionalOffset.
+				var s = new Size(vw / WorldDownscaleFactor + 1, vh / WorldDownscaleFactor + 1);
+				var fractionalOffset = centerLocation - viewportLocation;
+				worldSprite = new Sprite(worldSheet, new Rectangle(int2.Zero, s), 0, fractionalOffset, TextureChannel.RGBA);
 			}
 
 			worldBuffer.Bind();
-
-			if (lastWorldViewport != worldViewport)
+			var rect = new Rectangle(centerLocation, viewportSize);
+			if (lastWorldViewport != rect)
 			{
-				WorldSpriteRenderer.SetViewportParams(worldSheet.Size, WorldDownscaleFactor, depthMargin, worldViewport.Location);
-				lastWorldViewport = worldViewport;
+				var topLeft = centerLocation - viewportSize.ToInt2() / 2;
+				WorldSpriteRenderer.SetViewportParams(worldSheet.Size, WorldDownscaleFactor, depthMargin, topLeft);
+				lastWorldViewport = rect;
 			}
 
 			renderType = RenderType.World;
@@ -282,9 +289,11 @@ namespace OpenRA
 				screenBuffer.Bind();
 
 				var scale = Window.EffectiveWindowScale;
+
+				// We added 1 to worldSprite now we need to subtract.
 				var bufferScale = new float3(
-					(int)(screenSprite.Bounds.Width / scale) / worldSprite.Size.X,
-					(int)(-screenSprite.Bounds.Height / scale) / worldSprite.Size.Y,
+					(int)(screenSprite.Bounds.Width / scale) / (worldSprite.Size.X - 1),
+					(int)(-screenSprite.Bounds.Height / scale) / (worldSprite.Size.Y - 1),
 					1f);
 
 				SpriteRenderer.EnablePixelArtScaling(true);

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

@@ -240,7 +240,7 @@ namespace OpenRA.Mods.Common.Traits
 
 		void IRenderAboveWorld.RenderAboveWorld(Actor self, WorldRenderer wr)
 		{
-			var center = wr.Viewport.CenterLocation;
+			var center = wr.Viewport.CenterLocation.ToInt2();
 			var viewport = new Rectangle(center - new int2(viewportSize) / 2, viewportSize);
 			var wcr = Game.Renderer.WorldRgbaColorRenderer;
 

OpenRA.Mods.Common/Widgets/Logic/PerfDebugLogic.cs

@@ -47,7 +47,7 @@ namespace OpenRA.Mods.Common.Widgets.Logic
 				var fps = (newestFrame - oldestFrame) / (newestTime - oldestTime).TotalSeconds;
 
 				var wfbSize = Game.Renderer.WorldFrameBufferSize;
-				var viewportSize = worldRenderer.Viewport.Rectangle.Size;
+				var viewportSize = worldRenderer.Viewport.ViewportSize;
 				return $"FPS: {fps:0}\nTick {Game.LocalTick} @ {PerfHistory.Items["tick_time"].Average(Game.Settings.Debug.Samples):F1} ms\n" +
 					$"Render {Game.RenderFrame} @ {PerfHistory.Items["render"].Average(Game.Settings.Debug.Samples):F1} ms\n" +
 					$"Batches: {PerfHistory.Items["batches"].LastValue}\n" +