From bb15bd20c07c368cd5092f63f8702527d96022bb Mon Sep 17 00:00:00 2001
From: Paul Chote <pchote@users.noreply.github.com>
Date: Fri, 23 Apr 2021 22:38:11 +0100
Subject: [PATCH] Add support for 16 bit floating point textures.

---
 OpenRA.Game/Graphics/PlatformInterfaces.cs    |  1 +
 OpenRA.Platforms.Default/OpenGL.cs            |  2 ++
 OpenRA.Platforms.Default/Texture.cs           | 19 +++++++++++++++
 .../ThreadedGraphicsContext.cs                | 23 +++++++++++++++++++
 4 files changed, 45 insertions(+)

diff --git a/OpenRA.Game/Graphics/PlatformInterfaces.cs b/OpenRA.Game/Graphics/PlatformInterfaces.cs
index 3f30b9e7c6..5d8113d591 100644
--- a/OpenRA.Game/Graphics/PlatformInterfaces.cs
+++ b/OpenRA.Game/Graphics/PlatformInterfaces.cs
@@ -125,6 +125,7 @@ namespace OpenRA
 	{
 		void SetData(uint[,] colors);
 		void SetData(byte[] colors, int width, int height);
+		void SetFloatData(float[] data, int width, int height);
 		byte[] GetData();
 		Size Size { get; }
 		TextureScaleFilter ScaleFilter { get; set; }
diff --git a/OpenRA.Platforms.Default/OpenGL.cs b/OpenRA.Platforms.Default/OpenGL.cs
index fc7adbee53..db6062f60b 100644
--- a/OpenRA.Platforms.Default/OpenGL.cs
+++ b/OpenRA.Platforms.Default/OpenGL.cs
@@ -144,6 +144,8 @@ namespace OpenRA.Platforms.Default
 		public const int GL_INFO_LOG_LENGTH = 0x8B84;
 		public const int GL_ACTIVE_UNIFORMS = 0x8B86;
 
+		public const int GL_RGBA16F = 0x881A;
+
 		// OpenGL 4.3
 		public const int GL_DEBUG_OUTPUT = 0x92E0;
 		public const int GL_DEBUG_OUTPUT_SYNCHRONOUS = 0x8242;
diff --git a/OpenRA.Platforms.Default/Texture.cs b/OpenRA.Platforms.Default/Texture.cs
index a3feb44e2c..024f963522 100644
--- a/OpenRA.Platforms.Default/Texture.cs
+++ b/OpenRA.Platforms.Default/Texture.cs
@@ -110,6 +110,25 @@ namespace OpenRA.Platforms.Default
 			}
 		}
 
+		public void SetFloatData(float[] data, int width, int height)
+		{
+			VerifyThreadAffinity();
+			if (!Exts.IsPowerOf2(width) || !Exts.IsPowerOf2(height))
+				throw new InvalidDataException("Non-power-of-two array {0}x{1}".F(width, height));
+
+			Size = new Size(width, height);
+			unsafe
+			{
+				fixed (float* ptr = &data[0])
+				{
+					PrepareTexture();
+					OpenGL.glTexImage2D(OpenGL.GL_TEXTURE_2D, 0, OpenGL.GL_RGBA16F, width, height,
+						0, OpenGL.GL_RGBA, OpenGL.GL_FLOAT, new IntPtr(ptr));
+					OpenGL.CheckGLError();
+				}
+			}
+		}
+
 		public byte[] GetData()
 		{
 			VerifyThreadAffinity();
diff --git a/OpenRA.Platforms.Default/ThreadedGraphicsContext.cs b/OpenRA.Platforms.Default/ThreadedGraphicsContext.cs
index a62575793c..62560099d2 100644
--- a/OpenRA.Platforms.Default/ThreadedGraphicsContext.cs
+++ b/OpenRA.Platforms.Default/ThreadedGraphicsContext.cs
@@ -560,6 +560,8 @@ namespace OpenRA.Platforms.Default
 		readonly Func<object, object> setData1;
 		readonly Action<object> setData2;
 		readonly Func<object, object> setData3;
+		readonly Action<object> setData4;
+		readonly Func<object, object> setData5;
 		readonly Action dispose;
 
 		public ThreadedTexture(ThreadedGraphicsContext device, ITextureInternal texture)
@@ -574,6 +576,8 @@ namespace OpenRA.Platforms.Default
 			setData1 = colors => { texture.SetData((uint[,])colors); return null; };
 			setData2 = tuple => { var t = (ValueTuple<byte[], int, int>)tuple; texture.SetData(t.Item1, t.Item2, t.Item3); };
 			setData3 = tuple => { setData2(tuple); return null; };
+			setData4 = tuple => { var t = (ValueTuple<float[], int, int>)tuple; texture.SetFloatData(t.Item1, t.Item2, t.Item3); };
+			setData5 = tuple => { setData4(tuple); return null; };
 			dispose = texture.Dispose;
 		}
 
@@ -623,6 +627,25 @@ namespace OpenRA.Platforms.Default
 			}
 		}
 
+		public void SetFloatData(float[] data, int width, int height)
+		{
+			// Objects 85000 bytes or more will be directly allocated in the Large Object Heap (LOH).
+			// https://docs.microsoft.com/en-us/dotnet/standard/garbage-collection/large-object-heap
+			if (data.Length < 21250)
+			{
+				// If we are able to create a small array the GC can collect easily, post a message to avoid blocking.
+				var temp = new float[data.Length];
+				Array.Copy(data, temp, temp.Length);
+				device.Post(setData4, (temp, width, height));
+			}
+			else
+			{
+				// If the length is large and would result in an array on the Large Object Heap (LOH),
+				// send a message and block to avoid LOH allocation as this requires a Gen2 collection.
+				device.Send(setData5, (data, width, height));
+			}
+		}
+
 		public void Dispose()
 		{
 			device.Post(dispose);