fix minor oopsies / dumbs with previous commit

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

@@ -53,13 +53,9 @@ namespace BizHawk.Bizware.Graphics
 			_minorVersion = minorVersion;
 			_forwardCompatible = forwardCompatible;
 
-			// we need an active context in order to acquire these functions
-			// technically, they could be different between contexts
-			// but with the exact same requested version and config that is highly unlikely in practice
-			using (new SDL2OpenGLContext(majorVersion, minorVersion, forwardCompatible))
-			{
-				GL = GL.GetApi(SDL2OpenGLContext.GetGLProcAddress);
-			}
+			// the loading of symbols is delayed until actual use, so no need to create a context now
+			// if you want to do offscreen work with this GL make a dummy control or an SDL2OpenGLContext
+			GL = GL.GetApi(SDL2OpenGLContext.GetGLProcAddress);
 
 			// misc initialization
 			CreateRenderStates();
@@ -75,6 +71,7 @@ namespace BizHawk.Bizware.Graphics
 
 		public void Dispose()
 		{
+			GL.Dispose();
 		}
 
 		public void Clear(BizClearBufferMask mask)

src/BizHawk.Bizware.Graphics/OpenGL/SDL2OpenGLContext.cs

@@ -1,6 +1,8 @@
 using System;
 using System.Runtime.InteropServices;
 
+using Silk.NET.OpenGL.Legacy;
+
 using static SDL2.SDL;
 
 namespace BizHawk.Bizware.Graphics
@@ -40,9 +42,6 @@ namespace BizHawk.Bizware.Graphics
 			SDL_SetHint(SDL_HINT_VIDEO_FOREIGN_WINDOW_OPENGL, "1");
 		}
 
-		[UnmanagedFunctionPointer(CallingConvention.Winapi)]
-		private delegate IntPtr glGetStringDelegate(int name);
-
 		private static readonly Lazy<int> _version = new(() =>
 		{
 			var prevWindow = SDL_GL_GetCurrentWindow();
@@ -52,21 +51,8 @@ namespace BizHawk.Bizware.Graphics
 			{
 				using (new SDL2OpenGLContext(2, 0, false))
 				{
-					var getStringFp = GetGLProcAddress("glGetString");
-					if (getStringFp == IntPtr.Zero) // uhhh?
-					{
-						return 0;
-					}
-
-					var getStringFunc = Marshal.GetDelegateForFunctionPointer<glGetStringDelegate>(getStringFp);
-					const int GL_VERSION = 0x1F02;
-					var version = getStringFunc(GL_VERSION);
-					if (version == IntPtr.Zero)
-					{
-						return 0;
-					}
-
-					var versionString = Marshal.PtrToStringAnsi(version);
+					using var gl = GL.GetApi(GetGLProcAddress);
+					var versionString = gl.GetStringS(StringName.Version);
 					var versionParts = versionString!.Split('.');
 					var major = int.Parse(versionParts[0]);
 					var minor = int.Parse(versionParts[1][0].ToString());

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

@@ -196,8 +196,6 @@ namespace BizHawk.Client.Common
 
 		private RetroShaderChain _shaderChainUser;
 
-		public virtual void ActivateOpenGLContext() => throw new NotImplementedException();
-
 		protected virtual void ActivateGraphicsControlContext() => throw new NotImplementedException();
 
 		protected virtual void SwapBuffersOfGraphicsControl() => throw new NotImplementedException();

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

@@ -36,7 +36,7 @@ namespace BizHawk.Client.EmuHawk
 			_getIsSecondaryThrottlingDisabled = getIsSecondaryThrottlingDisabled;
 		}
 
-		public override void ActivateOpenGLContext()
+		public void ActivateOpenGLContext()
 		{
 			if (_gl.DispMethodEnum == EDispMethod.OpenGL)
 			{

src/BizHawk.Client.EmuHawk/Program.cs

@@ -233,7 +233,11 @@ namespace BizHawk.Client.EmuHawk
 							new ExceptionBox(new Exception($"Initialization of OpenGL Display Method failed; falling back to {fallback.Name}")).ShowDialog();
 							return TryInitIGL(initialConfig.DispMethod = fallback.Method);
 						}
-						return CheckRenderer(new IGL_OpenGL(2, 0, false));
+						// need to have a context active for checking renderer, will be disposed afterwards
+						using (new SDL2OpenGLContext(2, 0, false))
+						{
+							return CheckRenderer(new IGL_OpenGL(2, 0, false));
+						}
 					default:
 					case EDispMethod.GdiPlus:
 						static GLControlWrapper_GdiPlus CreateGLControlWrapper(IGL_GdiPlus self) => new(self); // inlining as lambda causes crash, don't wanna know why --yoshi