GS/OGL: Add fallback when copy image is not supported.

pcsx2/GS/Renderers/OpenGL/GSDeviceOGL.cpp

@@ -76,6 +76,12 @@ namespace Emulate_DSA
 		glTexSubImage2D(GL_TEXTURE_2D, level, xoffset, yoffset, width, height, format, type, pixels);
 	}
 
+	static void GLAPIENTRY CopyTextureSubImage(GLuint texture, GLint level, GLint xoffset, GLint yoffset, GLint x, GLint y, GLsizei width, GLsizei height)
+	{
+		BindTextureUnit(7, texture);
+		glCopyTexSubImage2D(GL_TEXTURE_2D, level, xoffset, yoffset, x, y, width, height);
+	}
+
 	static void GLAPIENTRY CompressedTextureSubImage(GLuint texture, GLint level, GLint xoffset, GLint yoffset,
 		GLsizei width, GLsizei height, GLenum format, GLsizei imageSize, const void* data)
 	{
@@ -115,6 +121,7 @@ namespace Emulate_DSA
 		glCreateTextures = CreateTexture;
 		glTextureStorage2D = TextureStorage;
 		glTextureSubImage2D = TextureSubImage;
+		glCopyTextureSubImage2D = CopyTextureSubImage;
 		glCompressedTextureSubImage2D = CompressedTextureSubImage;
 		glGetTextureImage = GetTexureImage;
 		glTextureParameteri = TextureParameteri;
@@ -669,9 +676,8 @@ bool GSDeviceOGL::CheckFeatures(bool& buggy_pbo)
 
 	if (!GLAD_GL_VERSION_4_3 && !GLAD_GL_ARB_copy_image && !GLAD_GL_EXT_copy_image)
 	{
-		Host::ReportFormattedErrorAsync(
-			"GS", "GL_ARB_copy_image is not supported, this is required for the OpenGL renderer.");
-		return false;
+		Host::AddOSDMessage(
+			"GL_ARB_copy_image is not supported, this will reduce performance.", Host::OSD_ERROR_DURATION);
 	}
 
 	if (!GLAD_GL_ARB_viewport_array)
@@ -1463,6 +1469,14 @@ void GSDeviceOGL::CopyRect(GSTexture* sTex, GSTexture* dTex, const GSVector4i& r
 		glCopyImageSubDataEXT(sid, GL_TEXTURE_2D, 0, r.x, r.y, 0, did, GL_TEXTURE_2D,
 			0, destX, destY, 0, r.width(), r.height(), 1);
 	}
+	else
+	{
+		// Slower copy (conversion is done)
+		glBindFramebuffer(GL_READ_FRAMEBUFFER, m_fbo_read);
+		glFramebufferTexture2D(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, sid, 0);
+		glCopyTextureSubImage2D(did, 0, r.x, r.y, r.x, r.y, r.width(), r.height());
+		glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);
+	}
 }
 
 void GSDeviceOGL::StretchRect(GSTexture* sTex, const GSVector4& sRect, GSTexture* dTex, const GSVector4& dRect, ShaderConvert shader, bool linear)