Set world framebuffer size based on minimum zoom.

This avoids reallocating buffers each time the player changes zoom level.

OpenRA.Game/Graphics/HardwarePalette.cs

@@ -18,15 +18,19 @@ namespace OpenRA.Graphics
 	public sealed class HardwarePalette : IDisposable
 	{
 		public ITexture Texture { get; private set; }
+		public ITexture ColorShifts { get; private set; }
+
 		public int Height { get; private set; }
 		readonly Dictionary<string, ImmutablePalette> palettes = new Dictionary<string, ImmutablePalette>();
 		readonly Dictionary<string, MutablePalette> mutablePalettes = new Dictionary<string, MutablePalette>();
 		readonly Dictionary<string, int> indices = new Dictionary<string, int>();
 		byte[] buffer = new byte[0];
+		float[] colorShiftBuffer = new float[0];
 
 		public HardwarePalette()
 		{
 			Texture = Game.Renderer.Context.CreateTexture();
+			ColorShifts = Game.Renderer.Context.CreateTexture();
 		}
 
 		public bool Contains(string name)
@@ -55,14 +59,18 @@ namespace OpenRA.Graphics
 			if (palettes.ContainsKey(name))
 				throw new InvalidOperationException($"Palette {name} has already been defined");
 
-			int index = palettes.Count;
+			// PERF: the first row in the palette textures is reserved as a placeholder for non-indexed sprites
+			// that do not have a color-shift applied. This provides a quick shortcut to avoid querying the
+			// color-shift texture for every pixel only to find that most are not shifted.
+			var index = palettes.Count + 1;
 			indices.Add(name, index);
 			palettes.Add(name, p);
 
-			if (palettes.Count > Height)
+			if (index >= Height)
 			{
-				Height = Exts.NextPowerOf2(palettes.Count);
+				Height = Exts.NextPowerOf2(index + 1);
 				Array.Resize(ref buffer, Height * Palette.Size * 4);
+				Array.Resize(ref colorShiftBuffer, Height * 4);
 			}
 
 			if (allowModifiers)
@@ -82,6 +90,21 @@ namespace OpenRA.Graphics
 			CopyBufferToTexture();
 		}
 
+		public void SetColorShift(string name, float hueOffset, float satOffset, float minHue, float maxHue)
+		{
+			var index = GetPaletteIndex(name);
+			colorShiftBuffer[4 * index + 0] = hueOffset;
+			colorShiftBuffer[4 * index + 1] = satOffset;
+			colorShiftBuffer[4 * index + 2] = minHue;
+			colorShiftBuffer[4 * index + 3] = maxHue;
+		}
+
+		public bool HasColorShift(string name)
+		{
+			var index = GetPaletteIndex(name);
+			return colorShiftBuffer[4 * index + 2] != 0 || colorShiftBuffer[4 * index + 3] != 0;
+		}
+
 		public void Initialize()
 		{
 			CopyModifiablePalettesToBuffer();
@@ -102,6 +125,7 @@ namespace OpenRA.Graphics
 		void CopyBufferToTexture()
 		{
 			Texture.SetData(buffer, Palette.Size, Height);
+			ColorShifts.SetFloatData(colorShiftBuffer, 1, Height);
 		}
 
 		public void ApplyModifiers(IEnumerable<IPaletteModifier> paletteMods)
@@ -125,6 +149,7 @@ namespace OpenRA.Graphics
 		public void Dispose()
 		{
 			Texture.Dispose();
+			ColorShifts.Dispose();
 		}
 	}
 }

OpenRA.Game/Graphics/PaletteReference.cs

@@ -28,5 +28,7 @@ namespace OpenRA.Graphics
 			this.index = index;
 			this.hardwarePalette = hardwarePalette;
 		}
+
+		public bool HasColorShift => hardwarePalette.HasColorShift(Name);
 	}
 }

OpenRA.Game/Graphics/SpriteRenderable.cs

@@ -41,6 +41,12 @@ namespace OpenRA.Graphics
 			this.isDecoration = isDecoration;
 			this.tintModifiers = tintModifiers;
 			this.alpha = alpha;
+
+			// PERF: Remove useless palette assignments for RGBA sprites
+			// HACK: This is working around the fact that palettes are defined on traits rather than sequences
+			// and can be removed once this has been fixed
+			if (sprite.Channel == TextureChannel.RGBA && !(palette?.HasColorShift ?? false))
+				this.palette = null;
 		}
 
 		public WPos Pos => pos + offset;

OpenRA.Game/Graphics/SpriteRenderer.cs

@@ -116,14 +116,28 @@ namespace OpenRA.Graphics
 			nv += 6;
 		}
 
+		float ResolveTextureIndex(Sprite s, PaletteReference pal)
+		{
+			if (pal == null)
+				return 0;
+
+			// PERF: Remove useless palette assignments for RGBA sprites
+			// HACK: This is working around the limitation that palettes are defined on traits rather than on sequences,
+			// and can be removed once this has been fixed
+			if (s.Channel == TextureChannel.RGBA && !pal.HasColorShift)
+				return 0;
+
+			return pal.TextureIndex;
+		}
+
 		public void DrawSprite(Sprite s, in float3 location, PaletteReference pal)
 		{
-			DrawSprite(s, location, pal.TextureIndex, s.Size);
+			DrawSprite(s, location, ResolveTextureIndex(s, pal), s.Size);
 		}
 
 		public void DrawSprite(Sprite s, in float3 location, PaletteReference pal, float3 size)
 		{
-			DrawSprite(s, location, pal.TextureIndex, size);
+			DrawSprite(s, location, ResolveTextureIndex(s, pal), size);
 		}
 
 		public void DrawSprite(Sprite s, in float3 a, in float3 b, in float3 c, in float3 d)
@@ -142,7 +156,7 @@ namespace OpenRA.Graphics
 
 		public void DrawSprite(Sprite s, in float3 location, PaletteReference pal, in float3 size, in float3 tint, float alpha)
 		{
-			DrawSprite(s, location, pal.TextureIndex, size, tint, alpha);
+			DrawSprite(s, location, ResolveTextureIndex(s, pal), size, tint, alpha);
 		}
 
 		public void DrawSprite(Sprite s, in float3 a, in float3 b, in float3 c, in float3 d, in float3 tint, float alpha)
@@ -189,9 +203,10 @@ namespace OpenRA.Graphics
 			nv += v.Length;
 		}
 
-		public void SetPalette(ITexture palette)
+		public void SetPalette(ITexture palette, ITexture colorShifts)
 		{
 			shader.SetTexture("Palette", palette);
+			shader.SetTexture("ColorShifts", colorShifts);
 		}
 
 		public void SetViewportParams(Size screen, float depthScale, float depthOffset, int2 scroll)

OpenRA.Game/Graphics/TerrainSpriteLayer.cs

@@ -164,6 +164,12 @@ namespace OpenRA.Graphics
 					throw new InvalidDataException("Attempted to add sprite with a different blend mode");
 
 				samplers = new int2(GetOrAddSheetIndex(sprite.Sheet), GetOrAddSheetIndex((sprite as SpriteWithSecondaryData)?.SecondarySheet));
+
+				// PERF: Remove useless palette assignments for RGBA sprites
+				// HACK: This is working around the limitation that palettes are defined on traits rather than on sequences,
+				// and can be removed once this has been fixed
+				if (sprite.Channel == TextureChannel.RGBA && !(palette?.HasColorShift ?? false))
+					palette = null;
 			}
 			else
 			{

OpenRA.Game/Graphics/UISpriteRenderable.cs

@@ -32,6 +32,12 @@ namespace OpenRA.Graphics
 			this.palette = palette;
 			this.scale = scale;
 			this.alpha = alpha;
+
+			// PERF: Remove useless palette assignments for RGBA sprites
+			// HACK: This is working around the fact that palettes are defined on traits rather than sequences
+			// and can be removed once this has been fixed
+			if (sprite.Channel == TextureChannel.RGBA && !(palette?.HasColorShift ?? false))
+				this.palette = null;
 		}
 
 		// Does not exist in the world, so a world positions don't make sense

OpenRA.Game/Graphics/WorldRenderer.cs

@@ -109,6 +109,11 @@ namespace OpenRA.Graphics
 				palettes[name].Palette = pal;
 		}
 
+		public void SetPaletteColorShift(string name, float hueOffset, float satOffset, float minHue, float maxHue)
+		{
+			palette.SetColorShift(name, hueOffset, satOffset, minHue, maxHue);
+		}
+
 		// PERF: Avoid LINQ.
 		void GenerateRenderables()
 		{