Change RenderTarget to IRenderTarget, implement classes accordingly

Changes GDI+ handling quite a bit, hopefully didn't break anything

src/BizHawk.Bizware.Graphics.Controls/Controls/GDIPlusControl.cs

@@ -9,15 +9,19 @@ namespace BizHawk.Bizware.Graphics.Controls
 {
 	internal sealed class GDIPlusControl : GraphicsControl
 	{
-		public GDIPlusControl(Func<Func<(SDGraphics Graphics, Rectangle Rectangle)>, GDIPlusRenderTarget> createControlRenderTarget)
+		/// <summary>
+		/// The render target for rendering to this control
+		/// </summary>
+		private readonly GDIPlusControlRenderTarget _renderTarget;
+
+		public GDIPlusControl(Func<Func<(SDGraphics Graphics, Rectangle Rectangle)>, GDIPlusControlRenderTarget> createControlRenderTarget)
 		{
-			RenderTarget = createControlRenderTarget(GetControlRenderContext);
+			_renderTarget = createControlRenderTarget(GetControlRenderContext);
 
 			SetStyle(ControlStyles.UserPaint, true);
 			SetStyle(ControlStyles.Opaque, true);
 			SetStyle(ControlStyles.UserMouse, true);
 			DoubleBuffered = true;
-			BackColor = Color.Black;
 		}
 
 		private (SDGraphics Graphics, Rectangle Rectangle) GetControlRenderContext()
@@ -28,11 +32,6 @@ namespace BizHawk.Bizware.Graphics.Controls
 			return (graphics, ClientRectangle);
 		}
 
-		/// <summary>
-		/// The render target for rendering to this control
-		/// </summary>
-		private GDIPlusRenderTarget RenderTarget { get; }
-
 		public override void AllowTearing(bool state)
 		{
 			// not controllable
@@ -54,22 +53,22 @@ namespace BizHawk.Bizware.Graphics.Controls
 		protected override void OnHandleCreated(EventArgs e)
 		{
 			base.OnHandleCreated(e);
-			RenderTarget.CreateGraphics();
+			_renderTarget.CreateGraphics();
 		}
 
 		protected override void OnHandleDestroyed(EventArgs e)
 		{
 			base.OnHandleDestroyed(e);
-			RenderTarget.Dispose();
+			_renderTarget.Dispose();
 		}
 
 		protected override void OnResize(EventArgs e)
 		{
 			base.OnResize(e);
-			RenderTarget.CreateGraphics();
+			_renderTarget.CreateGraphics();
 		}
 
 		public override void SwapBuffers()
-			=> RenderTarget.BufferedGraphics?.Render(RenderTarget.CurGraphics);
+			=> _renderTarget.BufferedGraphics?.Render(_renderTarget.ControlGraphics);
 	}
-}
+}

src/BizHawk.Bizware.Graphics/D3D11/D3D11RenderTarget.cs

@@ -0,0 +1,38 @@
+using Vortice.Direct3D11;
+using Vortice.DXGI;
+
+namespace BizHawk.Bizware.Graphics
+{
+	internal sealed class D3D11RenderTarget : D3D11Texture2D, IRenderTarget
+	{
+		public ID3D11RenderTargetView RTV;
+
+		public D3D11RenderTarget(D3D11Resources resources, int width, int height)
+			: base(resources, BindFlags.ShaderResource | BindFlags.RenderTarget, ResourceUsage.Default, CpuAccessFlags.None, width, height)
+		{
+		}
+
+		public override void CreateTexture()
+		{
+			base.CreateTexture();
+			var rtvd = new RenderTargetViewDescription(RenderTargetViewDimension.Texture2D, Format.B8G8R8A8_UNorm);
+			RTV = Device.CreateRenderTargetView(Texture, rtvd);
+		}
+
+		public override void DestroyTexture()
+		{
+			RTV?.Dispose();
+			RTV = null;
+			base.DestroyTexture();
+		}
+
+		public void Bind()
+		{
+			Context.OMSetRenderTargets(RTV);
+			_resources.CurRenderTarget = this;
+		}
+
+		public override string ToString()
+			=> $"D3D11 RenderTarget: {Width}x{Height}";
+	}
+}

src/BizHawk.Bizware.Graphics/D3D11/D3D11Resources.cs

@@ -26,8 +26,9 @@ namespace BizHawk.Bizware.Graphics
 
 		public FeatureLevel DeviceFeatureLevel;
 
-		public readonly HashSet<RenderTarget> RenderTargets = new();
+		public D3D11RenderTarget CurRenderTarget;
-		public readonly HashSet<D3D11Texture2D> ShaderTextures = new();
+
+		public readonly HashSet<D3D11Texture2D> Textures = new();
 		public readonly HashSet<Shader> VertexShaders = new();
 		public readonly HashSet<Shader> PixelShaders = new();
 		public readonly HashSet<Pipeline> Pipelines = new();
@@ -94,6 +95,11 @@ namespace BizHawk.Bizware.Graphics
 				RasterizerState = Device.CreateRasterizerState(rd);
 
 				Context.IASetPrimitiveTopology(PrimitiveTopology.TriangleStrip);
+
+				foreach (var tex2d in Textures)
+				{
+					tex2d.CreateTexture();
+				}
 			}
 			catch
 			{
@@ -102,8 +108,15 @@ namespace BizHawk.Bizware.Graphics
 			}
 		}
 
-		public void Dispose()
+		public void DestroyResources()
 		{
+			foreach (var tex2d in Textures)
+			{
+				tex2d.DestroyTexture();
+			}
+
+			CurRenderTarget = null;
+
 			LinearSamplerState?.Dispose();
 			LinearSamplerState = null;
 			PointSamplerState?.Dispose();
@@ -128,5 +141,11 @@ namespace BizHawk.Bizware.Graphics
 			Factory1?.Dispose();
 			Factory1 = null;
 		}
+
+		public void Dispose()
+		{
+			DestroyResources();
+			Textures.Clear();
+		}
 	}
 }

src/BizHawk.Bizware.Graphics/D3D11/D3D11Texture2D.cs

@@ -10,18 +10,18 @@ namespace BizHawk.Bizware.Graphics
 {
 	internal class D3D11Texture2D : ITexture2D
 	{
-		private readonly D3D11Resources _resources;
+		protected readonly D3D11Resources _resources;
 		private readonly BindFlags _bindFlags;
 		private readonly ResourceUsage _usage;
 		private readonly CpuAccessFlags _cpuAccessFlags;
 
-		private ID3D11Device Device => _resources.Device;
+		protected ID3D11Device Device => _resources.Device;
-		private ID3D11DeviceContext Context => _resources.Context;
+		protected ID3D11DeviceContext Context => _resources.Context;
-		private HashSet<D3D11Texture2D> ShaderTextures => _resources.ShaderTextures;
+		private HashSet<D3D11Texture2D> Textures => _resources.Textures;
 
 		private ID3D11Texture2D StagingTexture;
 
-		public ID3D11Texture2D Texture;
+		protected ID3D11Texture2D Texture;
 		public ID3D11ShaderResourceView SRV;
 		public bool LinearFiltering;
 
@@ -37,17 +37,18 @@ namespace BizHawk.Bizware.Graphics
 			_cpuAccessFlags = cpuAccessFlags;
 			Width = width;
 			Height = height;
+			// ReSharper disable once VirtualMemberCallInConstructor
 			CreateTexture();
-			ShaderTextures.Add(this);
+			Textures.Add(this);
 		}
 
 		public void Dispose()
 		{
 			DestroyTexture();
-			ShaderTextures.Remove(this);
+			Textures.Remove(this);
 		}
 
-		public void CreateTexture()
+		public virtual void CreateTexture()
 		{
 			Texture = Device.CreateTexture2D(
 				Format.B8G8R8A8_UNorm,
@@ -62,7 +63,7 @@ namespace BizHawk.Bizware.Graphics
 			SRV = Device.CreateShaderResourceView(Texture, srvd);
 		}
 
-		public void DestroyTexture()
+		public virtual void DestroyTexture()
 		{
 			SRV?.Dispose();
 			SRV = null;

src/BizHawk.Bizware.Graphics/D3D11/IGL_D3D11.cs

@@ -38,10 +38,10 @@ namespace BizHawk.Bizware.Graphics
 		private ID3D11RasterizerState RasterizerState => _resources.RasterizerState;
 
 		private FeatureLevel DeviceFeatureLevel => _resources.DeviceFeatureLevel;
+		private D3D11RenderTarget CurRenderTarget => _resources.CurRenderTarget;
 
 		// rendering state
 		private Pipeline _curPipeline;
-		private RenderTarget _curRenderTarget;
 		private D3D11SwapChain.SwapChainResources _controlSwapChain;
 
 		public IGL_D3D11()
@@ -151,32 +151,9 @@ namespace BizHawk.Bizware.Graphics
 				sw.PS = null;
 			}
 
-			foreach (var rw in _resources.RenderTargets.Select(rt => (RenderTargetWrapper)rt.Opaque))
+			_resources.DestroyResources();
-			{
-				rw.RTV.Dispose();
-				rw.RTV = null;
-			}
-
-			foreach (var tex2d in _resources.ShaderTextures)
-			{
-				tex2d.DestroyTexture();
-			}
-
-			_resources.Dispose();
 			_resources.CreateResources();
 
-			foreach (var tex2d in _resources.ShaderTextures)
-			{
-				tex2d.CreateTexture();
-			}
-
-			foreach (var rt in _resources.RenderTargets)
-			{
-				var rw = (RenderTargetWrapper)rt.Opaque;
-				var rtvd = new RenderTargetViewDescription(RenderTargetViewDimension.Texture2D, Format.B8G8R8A8_UNorm);
-				rw.RTV = Device.CreateRenderTargetView(((D3D11Texture2D)rt.Texture2D).Texture, rtvd);
-			}
-
 			foreach (var sw in _resources.VertexShaders.Select(vertexShader => (ShaderWrapper)vertexShader.Opaque))
 			{
 				sw.VS = Device.CreateVertexShader(sw.Bytecode.Span);
@@ -264,17 +241,7 @@ namespace BizHawk.Bizware.Graphics
 		}
 
 		public void ClearColor(Color color)
-		{
+			=> Context.ClearRenderTargetView(CurRenderTarget?.RTV ?? _controlSwapChain.RTV, new(color.R, color.B, color.G, color.A));
-			if (_curRenderTarget == null)
-			{
-				Context.ClearRenderTargetView(_controlSwapChain.RTV, new(color.R, color.B, color.G, color.A));
-			}
-			else
-			{
-				var rw = (RenderTargetWrapper)_curRenderTarget.Opaque;
-				Context.ClearRenderTargetView(rw.RTV, new(color.R, color.B, color.G, color.A));
-			}
-		}
 
 		private class ShaderWrapper // Disposable fields cleaned up by Internal_FreeShader
 		{
@@ -607,11 +574,6 @@ namespace BizHawk.Bizware.Graphics
 			public ShaderWrapper VertexShader, FragmentShader;
 		}
 
-		private class RenderTargetWrapper
-		{
-			public ID3D11RenderTargetView RTV;
-		}
-
 		private class VertexLayoutWrapper
 		{
 			public ID3D11InputLayout VertexInputLayout;
@@ -875,36 +837,13 @@ namespace BizHawk.Bizware.Graphics
 			Context.RSSetScissorRect(x, y, width, height);
 		}
 
-		public void FreeRenderTarget(RenderTarget rt)
+		public IRenderTarget CreateRenderTarget(int width, int height)
+			=> new D3D11RenderTarget(_resources, width, height);
+
+		public void BindDefaultRenderTarget()
 		{
-			var rw = (RenderTargetWrapper)rt.Opaque;
+			_resources.CurRenderTarget = null;
-			rw.RTV.Dispose();
+			Context.OMSetRenderTargets(_controlSwapChain.RTV);
-			_resources.RenderTargets.Remove(rt);
-			rt.Texture2D.Dispose();
-		}
-
-		public RenderTarget CreateRenderTarget(int width, int height)
-		{
-			var tex = new D3D11Texture2D(_resources, BindFlags.ShaderResource | BindFlags.RenderTarget, ResourceUsage.Default, CpuAccessFlags.None, width, height);
-			var rtvd = new RenderTargetViewDescription(RenderTargetViewDimension.Texture2D, Format.B8G8R8A8_UNorm);
-			var rw = new RenderTargetWrapper { RTV = Device.CreateRenderTargetView(tex.Texture, rtvd) };
-			var rt = new RenderTarget(this, rw, tex);
-			_resources.RenderTargets.Add(rt);
-			return rt;
-		}
-
-		public void BindRenderTarget(RenderTarget rt)
-		{
-			_curRenderTarget = rt;
-
-			if (rt == null)
-			{
-				Context.OMSetRenderTargets(_controlSwapChain.RTV);
-				return;
-			}
-
-			var rw = (RenderTargetWrapper)rt.Opaque;
-			Context.OMSetRenderTargets(rw.RTV);
 		}
 
 		public void Draw(IntPtr data, int count)

src/BizHawk.Bizware.Graphics/GDIPlus/GDIPlusControlRenderTarget.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Drawing;
+
+using SDGraphics = System.Drawing.Graphics;
+
+namespace BizHawk.Bizware.Graphics
+{
+	public sealed class GDIPlusControlRenderTarget : IDisposable
+	{
+		private readonly Func<(SDGraphics, Rectangle)> _getControlRenderContext;
+		private BufferedGraphicsContext _bufferedGraphicsContext = new();
+
+		public SDGraphics ControlGraphics;
+		public BufferedGraphics BufferedGraphics;
+
+		internal GDIPlusControlRenderTarget(Func<(SDGraphics Graphics, Rectangle Rectangle)> getControlRenderContext)
+			=> _getControlRenderContext = getControlRenderContext;
+
+		public void Dispose()
+		{
+			ControlGraphics?.Dispose();
+			ControlGraphics = null;
+			BufferedGraphics?.Dispose();
+			BufferedGraphics = null;
+			_bufferedGraphicsContext?.Dispose();
+			_bufferedGraphicsContext = null;
+		}
+
+		public void CreateGraphics()
+		{
+			ControlGraphics?.Dispose();
+			BufferedGraphics?.Dispose();
+			(ControlGraphics, var r) = _getControlRenderContext();
+			BufferedGraphics = _bufferedGraphicsContext.Allocate(ControlGraphics, r);
+		}
+	}
+}

src/BizHawk.Bizware.Graphics/GDIPlus/GDIPlusRenderTarget.cs

@@ -1,63 +1,30 @@
-using System;
-using System.Drawing;
-
 using SDGraphics = System.Drawing.Graphics;
 
 namespace BizHawk.Bizware.Graphics
 {
-	public class GDIPlusRenderTarget : IDisposable
+	internal sealed class GDIPlusRenderTarget : GDIPlusTexture2D, IRenderTarget
 	{
-		internal GDIPlusRenderTarget(Func<BufferedGraphicsContext> getBufferedGraphicsContext,
+		private readonly IGL_GDIPlus _gdiPlus;
-			Func<(SDGraphics Graphics, Rectangle Rectangle)> getControlRenderContext = null)
+		public SDGraphics TextureGraphics;
+
+		internal GDIPlusRenderTarget(IGL_GDIPlus gdiPlus, int width, int height)
+			: base(width, height)
 		{
-			_getBufferedGraphicsContext = getBufferedGraphicsContext;
+			_gdiPlus = gdiPlus;
-			_getControlRenderContext = getControlRenderContext;
+			TextureGraphics = SDGraphics.FromImage(SDBitmap);
 		}
 
-		public void Dispose()
+		public override void Dispose()
 		{
-			if (_getControlRenderContext != null)
+			TextureGraphics?.Dispose();
-			{
+			TextureGraphics = null;
-				CurGraphics?.Dispose();
+			base.Dispose();
-				CurGraphics = null;
-			}
-
-			BufferedGraphics?.Dispose();
-			BufferedGraphics = null;
 		}
 
-		private readonly Func<BufferedGraphicsContext> _getBufferedGraphicsContext;
+		public void Bind()
+			=> _gdiPlus.CurRenderTarget = this;
 
-		/// <summary>
+		public override string ToString()
-		/// get Graphics and Rectangle from a control, if any
+			=> $"GDI+ RenderTarget: {Width}x{Height}";
-		/// </summary>
-		private readonly Func<(SDGraphics, Rectangle)> _getControlRenderContext;
-
-		/// <summary>
-		/// the offscreen render target, if that's what this is representing
-		/// </summary>
-		public RenderTarget Target;
-
-		public SDGraphics CurGraphics;
-		public BufferedGraphics BufferedGraphics;
-
-		public void CreateGraphics()
-		{
-			Rectangle r;
-			if (_getControlRenderContext != null)
-			{
-				(CurGraphics, r) = _getControlRenderContext();
-			}
-			else
-			{
-				var gtex = (GDIPlusTexture2D)Target.Texture2D;
-				CurGraphics?.Dispose();
-				CurGraphics = SDGraphics.FromImage(gtex.SDBitmap);
-				r = gtex.GetRectangle();
-			}
-
-			BufferedGraphics?.Dispose();
-			BufferedGraphics = _getBufferedGraphicsContext().Allocate(CurGraphics, r);
-		}
 	}
 }

src/BizHawk.Bizware.Graphics/GDIPlus/GDIPlusTexture2D.cs

@@ -3,7 +3,7 @@ using System.Drawing.Imaging;
 
 namespace BizHawk.Bizware.Graphics
 {
-	public class GDIPlusTexture2D : ITexture2D
+	internal class GDIPlusTexture2D : ITexture2D
 	{
 		public Bitmap SDBitmap;
 		public bool LinearFiltering;
@@ -19,7 +19,7 @@ namespace BizHawk.Bizware.Graphics
 			SDBitmap = new(width, height, PixelFormat.Format32bppArgb);
 		}
 
-		public void Dispose()
+		public virtual void Dispose()
 		{
 			SDBitmap?.Dispose();
 			SDBitmap = null;

src/BizHawk.Bizware.Graphics/GDIPlus/IGL_GDIPlus.cs

@@ -5,15 +5,22 @@ using System.Numerics;
 
 using SDGraphics = System.Drawing.Graphics;
 
-//TODO - maybe a layer to cache Graphics parameters (notably, filtering) ?
 namespace BizHawk.Bizware.Graphics
 {
 	public class IGL_GDIPlus : IGL
 	{
+		private GDIPlusControlRenderTarget _controlRenderTarget;
+
+		internal GDIPlusRenderTarget CurRenderTarget;
+
 		public EDispMethod DispMethodEnum => EDispMethod.GdiPlus;
 
 		public void Dispose()
-			=> BufferedGraphicsContext.Dispose();
+		{
+		}
+
+		internal SDGraphics GetCurrentGraphics()
+			=> CurRenderTarget?.TextureGraphics ?? _controlRenderTarget.BufferedGraphics.Graphics;
 
 		public void ClearColor(Color color)
 			=> GetCurrentGraphics().Clear(color);
@@ -118,62 +125,21 @@ namespace BizHawk.Bizware.Graphics
 		{
 		}
 
-		public void FreeRenderTarget(RenderTarget rt)
+		public IRenderTarget CreateRenderTarget(int width, int height)
-		{
+			=> new GDIPlusRenderTarget(this, width, height);
-			var grt = (GDIPlusRenderTarget)rt.Opaque;
-			grt.Dispose();
-		}
 
-		public RenderTarget CreateRenderTarget(int width, int height)
+		public void BindDefaultRenderTarget()
-		{
+			=> CurRenderTarget = null;
-			var tex2d = new GDIPlusTexture2D(width, height);
-			var grt = new GDIPlusRenderTarget(() => BufferedGraphicsContext);
-			var rt = new RenderTarget(this, grt, tex2d);
-			grt.Target = rt;
-			return rt;
-		}
 
-		public void BindRenderTarget(RenderTarget rt)
+		public GDIPlusControlRenderTarget CreateControlRenderTarget(Func<(SDGraphics Graphics, Rectangle Rectangle)> getControlRenderContext)
-		{
-			if (_currOffscreenGraphics != null)
-			{
-				_currOffscreenGraphics.Dispose();
-				_currOffscreenGraphics = null;
-			}
-
-			if (rt == null)
-			{
-				// null means to use the default RT for the current control
-				CurrentRenderTarget = _controlRenderTarget;
-			}
-			else
-			{
-				var gtex = (GDIPlusTexture2D)rt.Texture2D;
-				CurrentRenderTarget = (GDIPlusRenderTarget)rt.Opaque;
-				_currOffscreenGraphics = SDGraphics.FromImage(gtex.SDBitmap);
-			}
-		}
-
-		private GDIPlusRenderTarget _controlRenderTarget;
-
-		public GDIPlusRenderTarget CreateControlRenderTarget(Func<(SDGraphics Graphics, Rectangle Rectangle)> getControlRenderContext)
 		{
 			if (_controlRenderTarget != null)
 			{
 				throw new InvalidOperationException($"{nameof(IGL_GDIPlus)} can only have one control render target");
 			}
 
-			_controlRenderTarget = new(() => BufferedGraphicsContext, getControlRenderContext);
+			_controlRenderTarget = new(getControlRenderContext);
 			return _controlRenderTarget;
 		}
-
-		private SDGraphics _currOffscreenGraphics;
-
-		public SDGraphics GetCurrentGraphics()
-			=> _currOffscreenGraphics ?? CurrentRenderTarget.BufferedGraphics.Graphics;
-
-		public GDIPlusRenderTarget CurrentRenderTarget;
-
-		public readonly BufferedGraphicsContext BufferedGraphicsContext = new();
 	}
 }

src/BizHawk.Bizware.Graphics/Interfaces/IGL.cs

@@ -19,17 +19,17 @@ namespace BizHawk.Bizware.Graphics
 		EDispMethod DispMethodEnum { get; }
 
 		/// <summary>
-		/// Clears the color buffer with the specified color
+		/// Clears the currently bound render target with the specified color
 		/// </summary>
 		void ClearColor(Color color);
 
 		/// <summary>
-		/// compile a fragment shader. This is the simplified method. A more complex method may be added later which will accept multiple sources and preprocessor definitions independently
+		/// Compile a fragment shader. This is the simplified method. A more complex method may be added later which will accept multiple sources and preprocessor definitions independently
 		/// </summary>
 		Shader CreateFragmentShader(string source, string entry, bool required);
 
 		/// <summary>
-		/// compile a vertex shader. This is the simplified method. A more complex method may be added later which will accept multiple sources and preprocessor definitions independently
+		/// Compile a vertex shader. This is the simplified method. A more complex method may be added later which will accept multiple sources and preprocessor definitions independently
 		/// </summary>
 		Shader CreateVertexShader(string source, string entry, bool required);
 
@@ -59,40 +59,40 @@ namespace BizHawk.Bizware.Graphics
 		void SetPipelineUniformMatrix(PipelineUniform uniform, ref Matrix4x4 mat, bool transpose);
 
 		/// <summary>
-		/// sets a uniform value
+		/// Sets a uniform value
 		/// </summary>
 		void SetPipelineUniform(PipelineUniform uniform, Vector4 value);
 
 		/// <summary>
-		/// sets a uniform value
+		/// Sets a uniform value
 		/// </summary>
 		void SetPipelineUniform(PipelineUniform uniform, Vector2 value);
 
 		/// <summary>
-		/// sets a uniform value
+		/// Sets a uniform value
 		/// </summary>
 		void SetPipelineUniform(PipelineUniform uniform, float value);
 
 		/// <summary>
-		/// sets uniform values
+		/// Sets uniform values
 		/// </summary>
 		void SetPipelineUniform(PipelineUniform uniform, Vector4[] values);
 
 		/// <summary>
-		/// sets a uniform value
+		/// Sets a uniform value
 		/// </summary>
 		void SetPipelineUniform(PipelineUniform uniform, bool value);
 
 		/// <summary>
 		/// Draws based on the currently set pipeline
-		/// data contains vertexes based on the pipeline's VertexLayout
+		/// Data contains vertexes based on the pipeline's VertexLayout
-		/// count is the vertex count
+		/// Count is the vertex count
 		/// Vertexes must form triangle strips
 		/// </summary>
 		void Draw(IntPtr data, int count);
 
 		/// <summary>
-		/// creates a vertex layout resource
+		/// Creates a vertex layout resource
 		/// </summary>
 		VertexLayout CreateVertexLayout();
 
@@ -119,35 +119,32 @@ namespace BizHawk.Bizware.Graphics
 		ITexture2D WrapGLTexture2D(int glTexId, int width, int height);
 
 		/// <summary>
-		/// sets the viewport (and scissor) according to the provided specifications
+		/// Sets the viewport (and scissor) according to the provided specifications
 		/// </summary>
 		void SetViewport(int x, int y, int width, int height);
 
 		/// <summary>
-		/// generates a proper 2d othographic projection for the given destination size, suitable for use in a GUI
+		/// Generates a proper 2D othographic projection for the given destination size, suitable for use in a GUI
 		/// </summary>
 		Matrix4x4 CreateGuiProjectionMatrix(int width, int height);
 
 		/// <summary>
-		/// generates a proper view transform for a standard 2d ortho projection, including half-pixel jitter if necessary and
+		/// Generates a proper view transform for a standard 2D othographic projection, including half-pixel jitter if necessary
-		/// re-establishing of a normal 2d graphics top-left origin. suitable for use in a GUI
+		/// and re-establishing of a normal 2D graphics top-left origin. Suitable for use in a GUI
 		/// </summary>
 		Matrix4x4 CreateGuiViewMatrix(int width, int height, bool autoflip = true);
 
 		/// <summary>
-		/// Creates a render target. Only includes a color buffer. Pixel format control TBD
+		/// Creates a render target. Only includes a color buffer, and will always be in byte order BGRA (i.e. little endian ARGB)
+		/// This may unbind a previously bound render target
 		/// </summary>
-		RenderTarget CreateRenderTarget(int width, int height);
+		IRenderTarget CreateRenderTarget(int width, int height);
 
 		/// <summary>
-		/// Binds a RenderTarget for current rendering
+		/// Binds the IGL's default render target (i.e. to the IGL's control)
+		/// This implicitly unbinds any previously bound IRenderTarget
 		/// </summary>
-		void BindRenderTarget(RenderTarget rt);
+		void BindDefaultRenderTarget();
-
-		/// <summary>
-		/// Frees the provided render target. Same as disposing the resource.
-		/// </summary>
-		void FreeRenderTarget(RenderTarget rt);
 
 		/// <summary>
 		/// Frees the provided pipeline. Same as disposing the resource.

src/BizHawk.Bizware.Graphics/Interfaces/IRenderTarget.cs

@@ -0,0 +1,15 @@
+namespace BizHawk.Bizware.Graphics
+{
+	/// <summary>
+	/// A render target, essentially just a 2D texture which can be written as if it was a window
+	/// As this is effectively a texture, it inherits ITexture2D
+	/// However, note that semantically the CPU shouldn't be writing to a render target, so LoadFrom might not work!
+	/// </summary>
+	public interface IRenderTarget : ITexture2D
+	{
+		/// <summary>
+		/// Binds this render target
+		/// </summary>
+		void Bind();
+	}
+}

src/BizHawk.Bizware.Graphics/OpenGL/IGL_OpenGL.cs

@@ -34,7 +34,7 @@ namespace BizHawk.Bizware.Graphics
 
 		// rendering state
 		private Pipeline _currPipeline;
-		private RenderTarget _currRenderTarget;
+		internal bool DefaultRenderTargetBound;
 
 		// this IGL either requires at least OpenGL 3.0
 		public static bool Available => OpenGLVersion.SupportsVersion(3, 0);
@@ -451,50 +451,14 @@ namespace BizHawk.Bizware.Graphics
 		public ITexture2D WrapGLTexture2D(int glTexId, int width, int height)
 			=> new OpenGLTexture2D(GL, (uint)glTexId, width, height);
 
-		public void FreeRenderTarget(RenderTarget rt)
-		{
-			rt.Texture2D.Dispose();
-			GL.DeleteFramebuffer((uint)rt.Opaque);
-		}
-
 		/// <exception cref="InvalidOperationException">framebuffer creation unsuccessful</exception>
-		public RenderTarget CreateRenderTarget(int width, int height)
+		public IRenderTarget CreateRenderTarget(int width, int height)
+			=> new OpenGLRenderTarget(this, GL, width, height);
+
+		public void BindDefaultRenderTarget()
 		{
-			// create a texture for it
-			var tex2d = new OpenGLTexture2D(GL, width, height);
-
-			// create the FBO
-			var fbId = GL.GenFramebuffer();
-			GL.BindFramebuffer(FramebufferTarget.Framebuffer, fbId);
-
-			// bind the tex to the FBO
-			GL.FramebufferTexture2D(FramebufferTarget.Framebuffer, FramebufferAttachment.ColorAttachment0, TextureTarget.Texture2D, tex2d.TexID, 0);
-
-			// do something, I guess say which color buffers are used by the framebuffer
-			GL.DrawBuffer(DrawBufferMode.ColorAttachment0);
-
-			if ((FramebufferStatus)GL.CheckFramebufferStatus(FramebufferTarget.Framebuffer) != FramebufferStatus.Complete)
-			{
-				throw new InvalidOperationException($"Error creating framebuffer (at {nameof(GL.CheckFramebufferStatus)})");
-			}
-
-			// since we're done configuring unbind this framebuffer, to return to the default
 			GL.BindFramebuffer(FramebufferTarget.Framebuffer, 0);
-
+			DefaultRenderTargetBound = true;
-			return new(this, fbId, tex2d);
-		}
-
-		public void BindRenderTarget(RenderTarget rt)
-		{
-			_currRenderTarget = rt;
-			if (rt == null)
-			{
-				GL.BindFramebuffer(FramebufferTarget.Framebuffer, 0);
-			}
-			else
-			{
-				GL.BindFramebuffer(FramebufferTarget.Framebuffer, (uint)rt.Opaque);
-			}
 		}
 
 		public Matrix4x4 CreateGuiProjectionMatrix(int width, int height)
@@ -511,7 +475,7 @@ namespace BizHawk.Bizware.Graphics
 			ret.M22 = -1.0f;
 			ret.M41 = width * -0.5f;
 			ret.M42 = height * 0.5f;
-			if (autoflip && _currRenderTarget is not null) // flip as long as we're not a final render target
+			if (autoflip && !DefaultRenderTargetBound) // flip as long as we're not a final render target
 			{
 				ret.M22 = 1.0f;
 				ret.M42 *= -1;

src/BizHawk.Bizware.Graphics/OpenGL/OpenGLRenderTarget.cs

@@ -0,0 +1,52 @@
+using System;
+
+using Silk.NET.OpenGL.Legacy;
+
+namespace BizHawk.Bizware.Graphics
+{
+	internal sealed class OpenGLRenderTarget : OpenGLTexture2D, IRenderTarget
+	{
+		private readonly IGL_OpenGL _openGL;
+		private readonly GL GL;
+
+		public readonly uint FBO;
+
+		public OpenGLRenderTarget(IGL_OpenGL openGL, GL gl, int width, int height)
+			: base(gl, width, height)
+		{
+			_openGL = openGL;
+			GL = gl;
+
+			// create the FBO
+			FBO = GL.GenFramebuffer();
+			Bind();
+
+			// bind the tex to the FBO
+			GL.FramebufferTexture2D(FramebufferTarget.Framebuffer, FramebufferAttachment.ColorAttachment0, TextureTarget.Texture2D, TexID, 0);
+
+			// do something, I guess say which color buffers are used by the framebuffer
+			GL.DrawBuffer(DrawBufferMode.ColorAttachment0);
+
+			if ((FramebufferStatus)GL.CheckFramebufferStatus(FramebufferTarget.Framebuffer) != FramebufferStatus.Complete)
+			{
+				Dispose();
+				throw new InvalidOperationException($"Error creating framebuffer (at {nameof(GL.CheckFramebufferStatus)})");
+			}
+		}
+
+		public override void Dispose()
+		{
+			GL.DeleteFramebuffer(FBO);
+			base.Dispose();
+		}
+
+		public void Bind()
+		{
+			GL.BindFramebuffer(FramebufferTarget.Framebuffer, FBO);
+			_openGL.DefaultRenderTargetBound = false;
+		}
+
+		public override string ToString()
+			=> $"OpenGL RenderTarget: {Width}x{Height}";
+	}
+}

src/BizHawk.Bizware.Graphics/OpenGL/OpenGLTexture2D.cs

@@ -44,7 +44,7 @@ namespace BizHawk.Bizware.Graphics
 			IsUpsideDown = true;
 		}
 
-		public void Dispose()
+		public virtual void Dispose()
 			=> GL.DeleteTexture(TexID);
 
 		public unsafe BitmapBuffer Resolve()

src/BizHawk.Bizware.Graphics/RenderTarget.cs

@@ -1,38 +0,0 @@
-using System;
-
-namespace BizHawk.Bizware.Graphics
-{
-	public class RenderTarget : IDisposable
-	{
-		public RenderTarget(IGL owner, object opaque, ITexture2D tex)
-		{
-			Owner = owner;
-			Opaque = opaque;
-			Texture2D = tex;
-		}
-
-		public override string ToString()
-		{
-			return $"GL RT: {Texture2D.Width}x{Texture2D.Height}";
-		}
-
-		public object Opaque { get; }
-		public IGL Owner { get; }
-		public ITexture2D Texture2D { get; }
-
-		public void Unbind()
-		{
-			Owner.BindRenderTarget(null);
-		}
-
-		public void Bind()
-		{
-			Owner.BindRenderTarget(this);
-		}
-
-		public void Dispose()
-		{
-			Owner.FreeRenderTarget(this);
-		}
-	}
-}

src/BizHawk.Client.Common/DisplayManager/DisplayManagerBase.cs

@@ -32,14 +32,14 @@ namespace BizHawk.Client.Common
 
 		protected class DisplayManagerRenderTargetProvider : IRenderTargetProvider
 		{
-			private readonly Func<Size, RenderTarget> _callback;
+			private readonly Func<Size, IRenderTarget> _callback;
 
-			RenderTarget IRenderTargetProvider.Get(Size size)
+			public IRenderTarget Get(Size size)
 			{
 				return _callback(size);
 			}
 
-			public DisplayManagerRenderTargetProvider(Func<Size, RenderTarget> callback)
+			public DisplayManagerRenderTargetProvider(Func<Size, IRenderTarget> callback)
 			{
 				_callback = callback;
 			}
@@ -864,7 +864,7 @@ namespace BizHawk.Client.Common
 		public void Blank()
 		{
 			ActivateGraphicsControlContext();
-			_gl.BindRenderTarget(null);
+			_gl.BindDefaultRenderTarget();
 			_gl.ClearColor(Color.Black);
 			SwapBuffersOfGraphicsControl();
 		}
@@ -880,11 +880,11 @@ namespace BizHawk.Client.Common
 
 			RunFilterChainSteps(ref rtCounter, out var rtCurr, out _);
 
-			job.OffscreenBb = rtCurr.Texture2D.Resolve();
+			job.OffscreenBb = rtCurr.Resolve();
 			job.OffscreenBb.DiscardAlpha();
 		}
 
-		protected void RunFilterChainSteps(ref int rtCounter, out RenderTarget rtCurr, out bool inFinalTarget)
+		protected void RunFilterChainSteps(ref int rtCounter, out IRenderTarget rtCurr, out bool inFinalTarget)
 		{
 			ITexture2D texCurr = null;
 			rtCurr = null;
@@ -907,7 +907,7 @@ namespace BizHawk.Client.Common
 					break;
 				case FilterProgram.ProgramStepType.FinalTarget:
 					_currentFilterProgram.CurrRenderTarget = rtCurr = null;
-					_gl.BindRenderTarget(rtCurr);
+					_gl.BindDefaultRenderTarget();
 					inFinalTarget = true;
 					break;
 				default:

src/BizHawk.Client.Common/DisplayManager/FilterManager.cs

@@ -38,7 +38,7 @@ namespace BizHawk.Client.Common.FilterManager
 
 	public interface IRenderTargetProvider
 	{
-		RenderTarget Get(Size size);
+		IRenderTarget Get(Size size);
 	}
 
 	public class FilterProgram
@@ -69,9 +69,9 @@ namespace BizHawk.Client.Common.FilterManager
 		public IGL GL;
 		public IRenderTargetProvider RenderTargetProvider;
 
-		public RenderTarget CurrRenderTarget;
+		public IRenderTarget CurrRenderTarget;
 
-		public RenderTarget GetTempTarget(int width, int height)
+		public IRenderTarget GetTempTarget(int width, int height)
 		{
 			return RenderTargetProvider.Get(new(width, height));
 		}

src/BizHawk.Client.Common/DisplayManager/Filters/BaseFilter.cs

@@ -111,7 +111,7 @@ namespace BizHawk.Client.Common.Filters
 		}
 
 		// TODO - why a different param order than DeclareOutput?
-		protected RenderTarget GetTempTarget(int width, int height)
+		protected IRenderTarget GetTempTarget(int width, int height)
 		{
 			return FilterProgram.GetTempTarget(width, height);
 		}

src/BizHawk.Client.Common/DisplayManager/Filters/Utils.cs

@@ -71,7 +71,7 @@ namespace BizHawk.Client.Common.Filters
 
 		public override void Run()
 		{
-			YieldOutput(FilterProgram.CurrRenderTarget.Texture2D);
+			YieldOutput(FilterProgram.CurrRenderTarget);
 		}
 	}
 }

src/BizHawk.Client.Common/DisplayManager/RenderTargetFrugalizer.cs

@@ -30,26 +30,26 @@ namespace BizHawk.Client.Common
 
 		private void ResetList()
 		{
-			_currentRenderTargets = new List<RenderTarget> { null, null };
+			_currentRenderTargets = new List<IRenderTarget> { null, null };
 		}
 
 		private readonly IGL _gl;
-		private List<RenderTarget> _currentRenderTargets;
+		private List<IRenderTarget> _currentRenderTargets;
 
-		public RenderTarget Get(Size dimensions)
+		public IRenderTarget Get(Size dimensions)
 		{
 			return Get(dimensions.Width, dimensions.Height);
 		}
 
-		public RenderTarget Get(int width, int height)
+		public IRenderTarget Get(int width, int height)
 		{
 			//get the current entry
 			var currentRenderTarget = _currentRenderTargets[0];
 
 			//check if its rotten and needs recreating
 			if (currentRenderTarget == null
-				|| currentRenderTarget.Texture2D.Width != width
+				|| currentRenderTarget.Width != width
-				|| currentRenderTarget.Texture2D.Height != height)
+				|| currentRenderTarget.Height != height)
 			{
 				// needs recreating. be sure to kill the old one...
 				currentRenderTarget?.Dispose();

src/BizHawk.Client.EmuHawk/DisplayManager/DisplayManager.cs

@@ -99,7 +99,7 @@ namespace BizHawk.Client.EmuHawk
 
 			if (job.Offscreen)
 			{
-				job.OffscreenBb = rtCurr.Texture2D.Resolve();
+				job.OffscreenBb = rtCurr.Resolve();
 				job.OffscreenBb.DiscardAlpha();
 				return;
 			}

src/BizHawk.Client.EmuHawk/GraphicsImplementations/RetainedGraphicsControl.cs

@@ -40,7 +40,7 @@ namespace BizHawk.Client.EmuHawk
 
 		private readonly IGL _gl;
 		private readonly GraphicsControl _graphicsControl;
-		private RenderTarget _rt;
+		private IRenderTarget _rt;
 		private readonly GuiRenderer _guiRenderer;
 
 		protected override void OnPaint(PaintEventArgs e)
@@ -75,7 +75,7 @@ namespace BizHawk.Client.EmuHawk
 		{
 			if (_retain)
 			{
-				_rt.Unbind();
+				_gl.BindDefaultRenderTarget();
 			}
 
 			_graphicsControl.End();
@@ -91,7 +91,7 @@ namespace BizHawk.Client.EmuHawk
 			}
 			
 			// if we're retaining, then we cant draw until we unbind! its semantically a bit odd, but we expect users to call SwapBuffers() before end, so we cant unbind in End() even thoug hit makes a bit more sense.
-			_rt.Unbind();
+			_gl.BindDefaultRenderTarget();
 			Draw();
 		}
 
@@ -104,9 +104,9 @@ namespace BizHawk.Client.EmuHawk
 
 			_guiRenderer.Begin(Width, Height);
 			_guiRenderer.DisableBlending();
-			_guiRenderer.Draw(_rt.Texture2D);
+			_guiRenderer.Draw(_rt);
 			_guiRenderer.End();
 			_graphicsControl.SwapBuffers();
 		}
 	}
-}
+}