Switch back to Asyncify without Emscripten Main Loop callback

.cargo/config.toml

@@ -3,9 +3,9 @@
 rustflags = [
     # "-O", "-C", "link-args=-O2 --profiling",
     #"-C", "link-args=-O3 --closure 1",
-    # "-C", "link-args=-sASYNCIFY -sALLOW_MEMORY_GROWTH=1",
-    "-C", "link-args=-sALLOW_MEMORY_GROWTH=1",
+    "-C", "link-args=-sASYNCIFY -sALLOW_MEMORY_GROWTH=1",
+    # "-C", "link-args=-sALLOW_MEMORY_GROWTH=1",
     "-C", "link-args=-sUSE_SDL=2 -sUSE_SDL_IMAGE=2 -sSDL2_IMAGE_FORMATS=['png']",
     # USE_OGG, USE_VORBIS for OGG/VORBIS usage
-    # "-C", "link-args=--preload-file ./assets/",
+    "-C", "link-args=--preload-file assets/",
 ]

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+    "rust-analyzer.linkedProjects": [
+        "./Cargo.toml"
+    ]
+}

scripts/build.sh

@@ -59,8 +59,8 @@ cp assets/index.html dist
 cp $output_folder/pacman.wasm dist
 cp $output_folder/pacman.js dist
 # only if .data file exists
-if [ -f $output_folder/pacman.data ]; then
-    cp $output_folder/pacman.data dist
+if [ -f $output_folder/deps/pacman.data ]; then
+    cp $output_folder/deps/pacman.data dist
 fi
 
 if [ "$serve" = 'true' ]; then

src/emscripten.rs

@@ -1,76 +1,44 @@
-// SOURCE: https://users.rust-lang.org/t/sdl2-emscripten-asmjs-and-invalid-renderer-panic/66567/2
 
-// Based on emscripten.rs from https://github.com/therocode/rust_emscripten_main_loop
-// This file interacts with the Emscripten API to provide a scheduling mechanism for main looping.
+pub mod emscripten {
+    use std::cell::RefCell;
+    use std::os::raw::{c_float, c_int, c_void};
+    use std::ptr::null_mut;
+    
+    #[allow(non_camel_case_types)]
+    type em_callback_func = unsafe extern "C" fn();
 
-// Since Emscripten only schedules the looping to be executed later by the browser, we need to make sure that the
-// data object looped upon lives as long as the looping is scheduled, as well as being properly destroyed afterwards.
+    extern "C" {
+        pub fn emscripten_set_main_loop(
+            func: em_callback_func,
+            fps: c_int,
+            simulate_infinite_loop: c_int,
+        );
+        pub fn emscripten_cancel_main_loop();
+        pub fn emscripten_get_now() -> c_float;
+    }
 
-// The Emscripten function used for this is emscripten_set_main_loop which will do the scheduling as well as terminate the current code flow
-// to prevent scopes from being exited which would cause objects to be destroyed prematurely. To be able to destroy the data object properly
-// as looping is terminated, the object is stored in thread_local storage.
+    thread_local!(static MAIN_LOOP_CALLBACK: RefCell<*mut c_void> = RefCell::new(null_mut()));
 
-use std::cell::RefCell;
-use std::os::raw::c_int;
-
-// Declare our FFI to the Emscripten functions we need. These will be linked in when building for Emscripten targets.
-#[allow(non_camel_case_types)]
-type em_callback_func = unsafe extern "C" fn();
-
-extern "C" {
-    pub fn emscripten_set_main_loop(
-        func: em_callback_func,
-        fps: c_int,
-        simulate_infinite_loop: c_int,
-    );
-    pub fn emscripten_cancel_main_loop();
-}
-
-thread_local! {
-    // This is where the data object will be kept during the scheduled looping. The storage structure is justified as follows
-
-    // thread_local - we need it outside of function scope. thread_local is enough since we only expect interactions from the same thread.
-    // RefCell<..> - allows for mutable access from anywhere which we need to store and then terminate. Still borrow-checked in runtime.
-    // Option<..> - we don't always have anything scheduled
-    // Box<dyn ...> - make it work generically for any closure passed in
-
-    static MAIN_LOOP_CLOSURE: RefCell<Option<Box<dyn FnMut()>>> = RefCell::new(None);
-}
-
-// Schedules the given callback to be run over and over in a loop until it returns MainLoopEvent::Terminate.
-// Retains ownership of the passed callback
-pub fn set_main_loop_callback<F: FnMut() + 'static>(callback: F) {
-    // Move the callback into the data storage for safe-keeping
-    MAIN_LOOP_CLOSURE.with(|d| {
-        *d.borrow_mut() = Some(Box::new(callback));
-    });
-
-    // Define a wrapper function that is compatible with the emscripten_set_main_loop function.
-    // This function will take care of extracting and executing our closure.
-    unsafe extern "C" fn wrapper<F: FnMut()>() {
-        // Access and run the stashed away closure
-        MAIN_LOOP_CLOSURE.with(|z| {
-            if let Some(closure) = &mut *z.borrow_mut() {
-                (*closure)();
-            }
+    pub fn set_main_loop_callback<F>(callback: F)
+    where
+        F: FnMut(),
+    {
+        MAIN_LOOP_CALLBACK.with(|log| {
+            *log.borrow_mut() = &callback as *const _ as *mut c_void;
         });
-    }
 
-    // Schedule the above wrapper function to be called regularly with Emscripten
-    unsafe {
-        emscripten_set_main_loop(wrapper::<F>, 0, 1);
-    }
-}
+        unsafe {
+            emscripten_set_main_loop(wrapper::<F>, 0, 1);
+        }
 
-// This is used to de-schedule the main loop function and destroy the kept closure object
-pub fn cancel_main_loop() {
-    // De-schedule
-    unsafe {
-        emscripten_cancel_main_loop();
+        unsafe extern "C" fn wrapper<F>()
+        where
+            F: FnMut(),
+        {
+            MAIN_LOOP_CALLBACK.with(|z| {
+                let closure = *z.borrow_mut() as *mut F;
+                (*closure)();
+            });
+        }
     }
-
-    // Remove the stored closure object
-    MAIN_LOOP_CLOSURE.with(|d| {
-        *d.borrow_mut() = None;
-    });
 }

src/main.rs

@@ -3,45 +3,51 @@ use std::process;
 use std::rc::Rc;
 
 use sdl2::event::Event;
+use sdl2::image::LoadTexture;
 use sdl2::keyboard::Keycode;
 use sdl2::pixels::Color;
-use sdl2::rect::Rect;
+use sdl2::rect::{Point, Rect};
 
 static BLACK: Color = Color::RGB(0, 0, 0);
 static WHITE: Color = Color::RGB(255, 255, 255);
 
-//     export EMCC_CFLAGS="-s USE_SDL=2"
-//     cargo build --target asmjs-unknown-emscripten && open index.html
-
 #[cfg(target_family = "wasm")]
 pub mod emscripten;
 
 fn main() {
+    // #[cfg(target_os = "emscripten")]
+    // sdl2::hint::set("SDL_EMSCRIPTEN_ASYNCIFY","1");
+    
     let ctx = sdl2::init().unwrap();
     let video_ctx = ctx.video().unwrap();
 
     let window = match video_ctx
         .window("Hello, Rust / SDL2 / WASM!", 640, 480)
         .position_centered()
-        .opengl()
+        // .opengl()
         .build()
     {
         Ok(window) => window,
         Err(err) => panic!("failed to create window: {}", err),
     };
 
-    let canvas = match window.into_canvas().present_vsync().build() {
+    let canvas = match window.into_canvas().accelerated().present_vsync().build() {
         Ok(canvas) => canvas,
         Err(err) => panic!("failed to create canvas: {}", err),
     };
 
-    let rect = Rect::new(0, 0, 10, 10);
+    let texture_creator = canvas.texture_creator();
+    let mut point = Point::new(0, 0);
 
     let ctx = Rc::new(RefCell::new(ctx));
-    let rect = Rc::new(RefCell::new(rect));
     let canvas = Rc::new(RefCell::new(canvas));
+    let texture_creator = Rc::new(texture_creator);
 
-    let main_loop = move || {
+    let fruit_atlas = texture_creator
+        .load_texture("./assets/fruit.png")
+        .expect("could not load texture");
+
+    let mut main_loop = move || {
         let mut moved = false;
         for event in ctx.borrow_mut().event_pump().unwrap().poll_iter() {
             match event {
@@ -53,67 +59,82 @@ fn main() {
                     process::exit(1);
                 }
                 Event::KeyDown {
-                    keycode: Some(key),
-                    ..
-                } => {
-                    match key {
-                        Keycode::Left => {
-                            rect.borrow_mut().x -= 10;
-                            moved = true;
-                        }
-                        Keycode::Right => {
-                            rect.borrow_mut().x += 10;
-                            moved = true;
-                        }
-                        Keycode::Up => {
-                            rect.borrow_mut().y -= 10;
-                            moved = true;
-                        }
-                        Keycode::Down => {
-                            rect.borrow_mut().y += 10;
-                            moved = true;
-                        }
-                        _ => {}
+                    keycode: Some(key), ..
+                } => match key {
+                    Keycode::Left => {
+                        point.x -= 32;
+                        moved = true;
                     }
-                }
+                    Keycode::Right => {
+                        point.x += 32;
+                        moved = true;
+                    }
+                    Keycode::Up => {
+                        point.y -= 32;
+                        moved = true;
+                    }
+                    Keycode::Down => {
+                        point.y += 32;
+                        moved = true;
+                    }
+                    _ => {}
+                },
                 _ => {}
             }
         }
 
         // Handle wrapping at the edges
         if moved {
-            let mut rect = rect.borrow_mut();
             let canvas_size = canvas.borrow().window().size();
-            if rect.x < 0 {
-                rect.x = canvas_size.0 as i32 - rect.width() as i32;
-            } else if rect.x >= 640 {
-                rect.x = 0;
+            if point.x < 0 {
+                point.x = canvas_size.0 as i32 - 32;
+            } else if point.x >= 640 {
+                point.x = 0;
             }
-            if rect.y < 0 {
-                rect.y = canvas_size.1 as i32 - rect.height() as i32;
-            } else if rect.y >= canvas_size.1 as i32 {
-                rect.y = 0;
+            if point.y < 0 {
+                point.y = canvas_size.1 as i32 - 32;
+            } else if point.y >= canvas_size.1 as i32 {
+                point.y = 0;
             }
         }
 
         let mut canvas = canvas.borrow_mut();
+
         canvas.set_draw_color(BLACK);
         canvas.clear();
-        canvas.set_draw_color(WHITE);
-        canvas.fill_rect(rect.borrow().clone()).expect("could not draw rectangle");
+
+        canvas
+            .copy_ex(
+                &fruit_atlas,
+                Rect::new(0, 0, 32, 32),
+                Rect::new(point.x, point.y, 32, 32),
+                0.0,
+                Some(Point::new(0, 0)),
+                false,
+                false,
+            )
+            .expect("could not draw texture");
+
         canvas.present();
     };
 
-    #[cfg(target_family = "wasm")]
-    emscripten::set_main_loop_callback(main_loop);
+    // #[cfg(target_family = "wasm")]
+    // {
+    //     use crate::emscripten::emscripten::set_main_loop_callback;
+    //     set_main_loop_callback(main_loop);
+    // }
 
-    #[cfg(not(target_family = "wasm"))]
-    {
-        use std::thread::sleep;
-        use std::time::Duration;
-        loop {
-            main_loop();
-            sleep(Duration::from_millis(10))
-        }
+    // #[cfg(not(target_family = "wasm"))]
+    // {
+    //     use std::thread::sleep;
+    //     use std::time::Duration;
+    //     loop {
+    //         main_loop();
+    //         sleep(Duration::from_millis(10))
+    //     }
+    // }
+
+    loop {
+        main_loop();
     }
 }