cleanup EGL + OpenGL init into given passes

crates/retro_frontend/src/libretro_callbacks.rs

@@ -247,7 +247,6 @@ pub(crate) unsafe extern "C" fn video_refresh_callback(
 					.resize((pitch * height as usize) as usize, 0);
 			}
 
-			// TODO: Make this convert from weird pitches to native resolution where possible.
 			for x in 0..pitch as usize {
 				for y in 0..height as usize {
 					let rgb = Rgb565::from_rgb565(pixel_data_slice[y * pitch as usize + x]);

crates/retrovnc/src/egl.rs

@@ -27,6 +27,29 @@ mod egl_impl {
 		devices: *mut EGLint,
 	) -> types::EGLBoolean;
 
+	/// A helper to get a display on the EGL "Device" platform, which allows headless rendering,
+	/// without any window system interface.
+	pub unsafe fn get_device_platform_display() -> types::EGLDisplay {
+		const NR_DEVICES_MAX: usize = 16;
+		let mut devices: [types::EGLDeviceEXT; NR_DEVICES_MAX] = [std::ptr::null(); NR_DEVICES_MAX];
+
+		let mut nr_devices_real: EGLint = 0;
+
+		let query_devices_ext: QueryDevicesExt =
+			std::mem::transmute(GetProcAddress(b"eglQueryDevicesEXT\0".as_ptr() as *const i8));
+		let get_platform_display_ext: GetPlatformDisplayExt = std::mem::transmute(GetProcAddress(
+			b"eglGetPlatformDisplayEXT\0".as_ptr() as *const i8,
+		));
+
+		(query_devices_ext)(
+			NR_DEVICES_MAX as i32,
+			devices.as_mut_ptr(),
+			std::ptr::addr_of_mut!(nr_devices_real),
+		);
+
+		(get_platform_display_ext)(PLATFORM_DEVICE_EXT, devices[0], std::ptr::null())
+	}
+
 	// link EGL as a library dependency
 	#[link(name = "EGL")]
 	extern "C" {}

crates/retrovnc/src/main.rs

@@ -1,4 +1,4 @@
-use std::{net::Ipv4Addr, path::Path};
+use std::{net::Ipv4Addr, path::Path, time::Duration};
 
 use anyhow::Result;
 
@@ -46,6 +46,10 @@ struct App {
 
 	hw_render: bool,
 
+	// EGL state
+	egl_display: egl::types::EGLDisplay,
+	egl_context: egl::types::EGLContext,
+
 	// OpenGL object IDs
 	texture_id: gl::types::GLuint,
 	renderbuffer_id: gl::types::GLuint,
@@ -62,6 +66,8 @@ impl App {
 			rfb_server: RfbServer::new(rfb_config)?,
 			pad: RetroPad::new(),
 			hw_render: false,
+			egl_display: std::ptr::null(),
+			egl_context: std::ptr::null(),
 			texture_id: 0,
 			renderbuffer_id: 0,
 			fbo_id: 0,
@@ -120,8 +126,72 @@ impl App {
 		Ok(())
 	}
 
-	fn hw_gl_resize(&mut self, width: u32, height: u32) {
+	/// Initalizes a headless EGL context for OpenGL rendering.
+	unsafe fn hw_gl_egl_init(&mut self) {
+		self.egl_display = egl::get_device_platform_display();
+
+		self.egl_context = {
+			const EGL_CONFIG_ATTRIBUTES: [egl::types::EGLenum; 13] = [
+				egl::SURFACE_TYPE,
+				egl::PBUFFER_BIT,
+				egl::BLUE_SIZE,
+				8,
+				egl::RED_SIZE,
+				8,
+				egl::BLUE_SIZE,
+				8,
+				egl::DEPTH_SIZE,
+				8,
+				egl::RENDERABLE_TYPE,
+				egl::OPENGL_BIT,
+				egl::NONE,
+			];
+			let mut egl_major: egl::EGLint = 0;
+			let mut egl_minor: egl::EGLint = 0;
+
+			let mut egl_config_count: egl::EGLint = 0;
+
+			let mut config: egl::types::EGLConfig = std::ptr::null();
+
+			egl::Initialize(
+				self.egl_display,
+				std::ptr::addr_of_mut!(egl_major),
+				std::ptr::addr_of_mut!(egl_minor),
+			);
+
+			egl::ChooseConfig(
+				self.egl_display,
+				EGL_CONFIG_ATTRIBUTES.as_ptr() as *const egl::EGLint,
+				std::ptr::addr_of_mut!(config),
+				1,
+				std::ptr::addr_of_mut!(egl_config_count),
+			);
+
+			egl::BindAPI(egl::OPENGL_API);
+
+			let context =
+				egl::CreateContext(self.egl_display, config, egl::NO_CONTEXT, std::ptr::null());
+
+			// Make the context current on the display so OpenGL routines "just work"
+			egl::MakeCurrent(self.egl_display, egl::NO_SURFACE, egl::NO_SURFACE, context);
+
+			context
+		};
+	}
+
+	/// Destroys EGL resources.
+	unsafe fn hw_gl_egl_exit(&mut self) {
+		// Release the EGL context we created before destroying it
+		egl::MakeCurrent(self.egl_display, egl::NO_SURFACE, egl::NO_SURFACE, egl::NO_CONTEXT);
+		egl::DestroyContext(self.egl_display, self.egl_context);
+		egl::Terminate(self.egl_display);
+		self.egl_display = std::ptr::null();
+		self.egl_context = std::ptr::null();
+	}
+
+	fn hw_gl_resize_fbo(&mut self, width: u32, height: u32) {
 		// TODO: cleanup "delete" codepaths so we aren't duplicating as much.
+		// (we should probably just have a "create" and "delete" FBO pair.)
 		unsafe {
 			if self.fbo_id == 0 {
 				gl::GenFramebuffers(1, std::ptr::addr_of_mut!(self.fbo_id));
@@ -195,6 +265,7 @@ impl App {
 			let id = self.fbo_id;
 			self.get_frontend().set_gl_fbo(id);
 
+			// Resize the readback buffer
 			self.readback_buffer.resize((width * height) as usize, 0);
 		}
 	}
@@ -204,12 +275,13 @@ impl App {
 		let frontend = self.get_frontend();
 
 		let av_info = frontend.get_av_info().expect("???");
-		let step_ms = ((1.0 / av_info.timing.fps) * 1000.) as u64;
+		let step_ms = (1.0 / av_info.timing.fps) * 1000.;
+		let step_duration = Duration::from_micros((step_ms * 1000.) as u64);
 
 		// Do the main loop
 		loop {
 			frontend.run_frame();
-			std::thread::sleep(std::time::Duration::from_millis(step_ms));
+			std::thread::sleep(step_duration);
 		}
 	}
 }
@@ -220,7 +292,7 @@ impl FrontendInterface for App {
 
 		// Resize OpenGL resources if we need to.
 		if self.hw_render {
-			self.hw_gl_resize(width, height);
+			self.hw_gl_resize_fbo(width, height);
 		}
 
 		self.rfb_server.resize(width as u16, height as u16);
@@ -274,19 +346,9 @@ impl FrontendInterface for App {
 			panic!("Cannot initalize HW rendering more than once");
 		}
 
-		let display = unsafe {
+		unsafe {
-			const NR_DEVICES_MAX: usize = 16;
+			// Initalize EGL
-			let mut devices: [egl::types::EGLDeviceEXT; NR_DEVICES_MAX] =
+			self.hw_gl_egl_init();
-				[std::ptr::null(); NR_DEVICES_MAX];
-
-			let mut nr_devices_real: egl::EGLint = 0;
-
-			let query_devices_ext: egl::QueryDevicesExt = std::mem::transmute(egl::GetProcAddress(
-				b"eglQueryDevicesEXT\0".as_ptr() as *const i8,
-			));
-			let get_platform_display_ext: egl::GetPlatformDisplayExt = std::mem::transmute(
-				egl::GetProcAddress(b"eglGetPlatformDisplayEXT\0".as_ptr() as *const i8),
-			);
 
 			// load OpenGL functions (using EGL loader. We should probably check the one extension exists)
 			gl::load_with(|s| {
@@ -294,66 +356,13 @@ impl FrontendInterface for App {
 				std::mem::transmute(egl::GetProcAddress(str.as_ptr()))
 			});
 
-			(query_devices_ext)(
+			// set OpenGL debug message callback
-				NR_DEVICES_MAX as i32,
-				devices.as_mut_ptr(),
-				std::ptr::addr_of_mut!(nr_devices_real),
-			);
-
-			(get_platform_display_ext)(egl::PLATFORM_DEVICE_EXT, devices[0], std::ptr::null())
-		};
-
-		let context = unsafe {
-			const EGL_CONFIG_ATTRIBUTES: [egl::types::EGLenum; 13] = [
-				egl::SURFACE_TYPE,
-				egl::PBUFFER_BIT,
-				egl::BLUE_SIZE,
-				8,
-				egl::RED_SIZE,
-				8,
-				egl::BLUE_SIZE,
-				8,
-				egl::DEPTH_SIZE,
-				8,
-				egl::RENDERABLE_TYPE,
-				egl::OPENGL_BIT,
-				egl::NONE,
-			];
-			let mut egl_major: egl::EGLint = 0;
-			let mut egl_minor: egl::EGLint = 0;
-
-			let mut egl_config_count: egl::EGLint = 0;
-
-			let mut config: egl::types::EGLConfig = std::ptr::null();
-
-			egl::Initialize(
-				display,
-				std::ptr::addr_of_mut!(egl_major),
-				std::ptr::addr_of_mut!(egl_minor),
-			);
-
-			egl::ChooseConfig(
-				display,
-				EGL_CONFIG_ATTRIBUTES.as_ptr() as *const egl::EGLint,
-				std::ptr::addr_of_mut!(config),
-				1,
-				std::ptr::addr_of_mut!(egl_config_count),
-			);
-
-			egl::BindAPI(egl::OPENGL_API);
-
-			egl::CreateContext(display, config, egl::NO_CONTEXT, std::ptr::null())
-		};
-
-		unsafe {
-			egl::MakeCurrent(display, egl::NO_SURFACE, egl::NO_SURFACE, context);
-
 			gl::Enable(gl::DEBUG_OUTPUT);
 			gl::DebugMessageCallback(Some(opengl_message_callback), std::ptr::null());
 
 			// Resize to initial dimensions (this will create an FBO as well)
 			let dimensions = self.get_frontend().get_size();
-			self.hw_gl_resize(dimensions.0, dimensions.1);
+			self.hw_gl_resize_fbo(dimensions.0, dimensions.1);
 		}
 
 		self.hw_render = true;