Refactor renderer initialization

src/framework/backend.rs

@@ -36,48 +36,65 @@ pub trait Backend {
 pub trait BackendEventLoop {
     fn run(&mut self, game: &mut Game, ctx: &mut Context);
 
-    fn new_renderer(&self, ctx: *mut Context) -> GameResult<Box<dyn BackendRenderer>>;
+    fn new_renderer(&self) -> GameResult<Box<dyn BackendRenderer>>;
 
     fn as_any(&self) -> &dyn Any;
 }
 
 pub trait BackendRenderer {
+    /// Human-readable name for the renderer. May return different values based on current platform or settings.
     fn renderer_name(&self) -> String;
 
+    /// Clear the current render target with the specified color.
     fn clear(&mut self, color: Color);
 
+    /// Present the current frame to the screen.
     fn present(&mut self) -> GameResult;
 
+    /// Sets the preferred frame swap mode.
     fn set_swap_mode(&mut self, _mode: SwapMode) -> GameResult {
         Ok(())
     }
 
+    // Prepare the renderer for drawing.
     fn prepare_draw(&mut self, _width: f32, _height: f32) -> GameResult {
         Ok(())
     }
 
+    /// Create a new mutable texture with the specified dimensions.
     fn create_texture_mutable(&mut self, width: u16, height: u16) -> GameResult<Box<dyn BackendTexture>>;
 
+    /// Create a new texture with the specified dimensions and data.
     fn create_texture(&mut self, width: u16, height: u16, data: &[u8]) -> GameResult<Box<dyn BackendTexture>>;
 
+    /// Set the current blend mode.
     fn set_blend_mode(&mut self, blend: BlendMode) -> GameResult;
 
+    /// Set the current render target.
     fn set_render_target(&mut self, texture: Option<&Box<dyn BackendTexture>>) -> GameResult;
 
+    /// Draw a filled rectangle with the specified color.
     fn draw_rect(&mut self, rect: Rect, color: Color) -> GameResult;
 
+    /// Draw an outlined rectangle with the specified line width and color.
     fn draw_outline_rect(&mut self, rect: Rect, line_width: usize, color: Color) -> GameResult;
 
+    /// Set the current clipping rectangle.
     fn set_clip_rect(&mut self, rect: Option<Rect>) -> GameResult;
 
+    /// Get a mutable reference to the imgui context.
     fn imgui(&self) -> GameResult<&mut imgui::Context>;
 
+    /// Get an imgui texture id for the specified texture.
     fn imgui_texture_id(&self, texture: &Box<dyn BackendTexture>) -> GameResult<imgui::TextureId>;
 
+    /// Prepare the imgui context for rendering.
     fn prepare_imgui(&mut self, ui: &imgui::Ui) -> GameResult;
 
+    /// Render the imgui draw data.
     fn render_imgui(&mut self, draw_data: &DrawData) -> GameResult;
 
+    /// Draw a list of triangles, in mode similar to GL_TRIANGLES.
     fn draw_triangle_list(
         &mut self,
         vertices: &[VertexData],
@@ -89,18 +106,23 @@ pub trait BackendRenderer {
 }
 
 pub trait BackendTexture {
+    /// Get the dimensions of the texture.
     fn dimensions(&self) -> (u16, u16);
 
+    /// Adds a new drawing command to the texture batch.
     fn add(&mut self, command: SpriteBatchCommand);
 
+    /// Clear the texture batch.
     fn clear(&mut self);
 
+    /// Draw the texture batch to the screen.
     fn draw(&mut self) -> GameResult;
 
     fn as_any(&self) -> &dyn Any;
 }
 
 pub trait BackendGamepad {
+    /// Run a gamepad rumble effect using the specified parameters.
     fn set_rumble(&mut self, low_freq: u16, high_freq: u16, duration_ms: u32) -> GameResult;
 
     fn instance_id(&self) -> u32;

src/framework/backend_horizon.rs

@@ -406,10 +406,8 @@ impl BackendEventLoop for HorizonEventLoop {
         }
     }
 
-    fn new_renderer(&self, ctx: *mut Context) -> GameResult<Box<dyn BackendRenderer>> {
+    fn new_renderer(&self) -> GameResult<Box<dyn BackendRenderer>> {
         let mut imgui = imgui::Context::create();
-        let ctx = unsafe { &mut *ctx };
-        imgui.io_mut().display_size = [ctx.screen_size.0, ctx.screen_size.1];
         imgui.fonts().build_alpha8_texture();
 
         let device = DeviceMaker::new().create();

src/framework/backend_null.rs

@@ -51,7 +51,7 @@ impl BackendEventLoop for NullEventLoop {
         }
     }
 
-    fn new_renderer(&self, _ctx: *mut Context) -> GameResult<Box<dyn BackendRenderer>> {
+    fn new_renderer(&self) -> GameResult<Box<dyn BackendRenderer>> {
         let mut imgui = imgui::Context::create();
         imgui.io_mut().display_size = [640.0, 480.0];
         imgui.fonts().build_alpha8_texture();

src/framework/backend_sdl2.rs

@@ -1,6 +1,7 @@
 use core::mem;
 use std::any::Any;
 use std::cell::RefCell;
+use std::collections::HashMap;
 use std::ffi::c_void;
 use std::io::Read;
 use std::ops::Deref;
@@ -146,7 +147,6 @@ impl WindowOrCanvas {
 struct SDL2EventLoop {
     event_pump: EventPump,
     refs: Rc<RefCell<SDL2Context>>,
-    opengl_available: RefCell<bool>,
 }
 
 struct SDL2Context {
@@ -156,6 +156,7 @@ struct SDL2Context {
     blend_mode: sdl2::render::BlendMode,
     fullscreen_type: sdl2::video::FullscreenType,
     game_controller: GameControllerSubsystem,
+    preferred_renderer: Option<String>,
 }
 
 impl SDL2EventLoop {
@@ -192,8 +193,6 @@ impl SDL2EventLoop {
             window.set_icon(icon);
         }
 
-        let opengl_available = if let Ok(v) = std::env::var("CAVESTORY_NO_OPENGL") { v != "1" } else { true };
-
         let event_loop = SDL2EventLoop {
             event_pump,
             refs: Rc::new(RefCell::new(SDL2Context {
@@ -203,8 +202,8 @@ impl SDL2EventLoop {
                 blend_mode: sdl2::render::BlendMode::Blend,
                 fullscreen_type: sdl2::video::FullscreenType::Off,
                 game_controller,
+                preferred_renderer: ctx.preferred_renderer.clone(),
             })),
-            opengl_available: RefCell::new(opengl_available),
         };
 
         Ok(Box::new(event_loop))
@@ -254,6 +253,80 @@ impl SDL2EventLoop {
 
         let _ = enabled;
     }
+
+    fn create_imgui() -> GameResult<imgui::Context> {
+        let mut imgui = init_imgui()?;
+
+        let mut key_map = &mut imgui.io_mut().key_map;
+        key_map[ImGuiKey_Backspace as usize] = Scancode::Backspace as u32;
+        key_map[ImGuiKey_Delete as usize] = Scancode::Delete as u32;
+        key_map[ImGuiKey_Enter as usize] = Scancode::Return as u32;
+
+        Ok(imgui)
+    }
+
+    #[cfg(feature = "render-opengl")]
+    fn try_create_opengl_renderer(&self) -> GameResult<Box<dyn BackendRenderer>> {
+        {
+            let mut refs = self.refs.borrow_mut();
+            match refs.window.window().gl_create_context() {
+                Ok(gl_ctx) => {
+                    refs.window.window().gl_make_current(&gl_ctx).map_err(|e| GameError::RenderError(e.to_string()))?;
+                    refs.gl_context = Some(gl_ctx);
+                }
+                Err(err) => {
+                    return Err(GameError::RenderError(format!("Failed to initialize OpenGL context: {}", err)));
+                }
+            }
+        }
+
+        struct SDL2GLPlatform(Rc<RefCell<SDL2Context>>);
+
+        impl render_opengl::GLPlatformFunctions for SDL2GLPlatform {
+            fn get_proc_address(&self, name: &str) -> *const c_void {
+                let refs = self.0.borrow();
+                refs.video.gl_get_proc_address(name) as *const _
+            }
+
+            fn swap_buffers(&self) {
+                let mut refs = self.0.borrow();
+                refs.window.window().gl_swap_window();
+            }
+
+            fn set_swap_mode(&self, mode: SwapMode) {
+                match mode {
+                    SwapMode::Immediate => unsafe {
+                        sdl2_sys::SDL_GL_SetSwapInterval(0);
+                    },
+                    SwapMode::VSync => unsafe {
+                        sdl2_sys::SDL_GL_SetSwapInterval(1);
+                    },
+                    SwapMode::Adaptive => unsafe {
+                        if sdl2_sys::SDL_GL_SetSwapInterval(-1) == -1 {
+                            log::warn!("Failed to enable variable refresh rate, falling back to non-V-Sync.");
+                            sdl2_sys::SDL_GL_SetSwapInterval(0);
+                        }
+                    },
+                }
+            }
+        }
+
+        let platform = Box::new(SDL2GLPlatform(self.refs.clone()));
+        let gl_context: GLContext = GLContext { gles2_mode: false, platform };
+
+        let imgui = Self::create_imgui()?;
+
+        OpenGLRenderer::new(gl_context, imgui)
+    }
+
+    fn try_create_sdl2_renderer(&self) -> GameResult<Box<dyn BackendRenderer>> {
+        let imgui = Self::create_imgui()?;
+        let mut refs = self.refs.borrow_mut();
+        let window = std::mem::take(&mut refs.window);
+        refs.window = window.make_canvas()?;
+
+        SDL2Renderer::new(self.refs.clone(), imgui)
+    }
 }
 
 impl BackendEventLoop for SDL2EventLoop {
@@ -440,74 +513,35 @@ impl BackendEventLoop for SDL2EventLoop {
         }
     }
 
-    fn new_renderer(&self, ctx: *mut Context) -> GameResult<Box<dyn BackendRenderer>> {
+    fn new_renderer(&self) -> GameResult<Box<dyn BackendRenderer>> {
-        #[cfg(feature = "render-opengl")]
+        let mut renderers = {
-        {
+            let mut renderers: Vec<(&'static str, fn(&Self) -> GameResult<Box<dyn BackendRenderer>>)> = Vec::new();
-            let mut refs = self.refs.borrow_mut();
+
-            match refs.window.window().gl_create_context() {
+            #[cfg(feature = "render-opengl")]
-                Ok(gl_ctx) => {
+            renderers.push((OpenGLRenderer::RENDERER_ID, Self::try_create_opengl_renderer));
-                    refs.window.window().gl_make_current(&gl_ctx).map_err(|e| GameError::RenderError(e.to_string()))?;
+
-                    refs.gl_context = Some(gl_ctx);
+            renderers.push((SDL2Renderer::RENDERER_ID, Self::try_create_sdl2_renderer));
-                }
+            renderers
-                Err(err) => {
+        };
-                    *self.opengl_available.borrow_mut() = false;
+
-                    log::error!("Failed to initialize OpenGL context, falling back to SDL2 renderer: {}", err);
+        if let Some(preferred_renderer) = &self.refs.borrow().preferred_renderer {
-                }
+            // remove the preferred renderer from the list
+            let index = renderers.iter().position(|(id, _)| id == preferred_renderer);
+            let pref_renderer = index.map(|index| renderers.remove(index));
+
+            if let Some(pref_renderer) = pref_renderer {
+                renderers.insert(0, pref_renderer);
             }
         }
 
-        let mut imgui = init_imgui()?;
+        for (id, renderer_fn) in renderers {
-
+            match renderer_fn(self) {
-        #[cfg(feature = "render-opengl")]
+                Ok(renderer) => return Ok(renderer),
-        if *self.opengl_available.borrow() {
+                Err(e) => log::warn!("Failed to create renderer {}: {}", id, e),
-            let mut key_map = &mut imgui.io_mut().key_map;
-            key_map[ImGuiKey_Backspace as usize] = Scancode::Backspace as u32;
-            key_map[ImGuiKey_Delete as usize] = Scancode::Delete as u32;
-            key_map[ImGuiKey_Enter as usize] = Scancode::Return as u32;
-
-            struct SDL2GLPlatform(Rc<RefCell<SDL2Context>>);
-
-            impl render_opengl::GLPlatformFunctions for SDL2GLPlatform {
-                fn get_proc_address(&self, name: &str) -> *const c_void {
-                    let refs = self.0.borrow();
-                    refs.video.gl_get_proc_address(name) as *const _
-                }
-
-                fn swap_buffers(&self) {
-                    let mut refs = self.0.borrow();
-                    refs.window.window().gl_swap_window();
-                }
-
-                fn set_swap_mode(&self, mode: SwapMode) {
-                    match mode {
-                        SwapMode::Immediate => unsafe {
-                            sdl2_sys::SDL_GL_SetSwapInterval(0);
-                        },
-                        SwapMode::VSync => unsafe {
-                            sdl2_sys::SDL_GL_SetSwapInterval(1);
-                        },
-                        SwapMode::Adaptive => unsafe {
-                            if sdl2_sys::SDL_GL_SetSwapInterval(-1) == -1 {
-                                log::warn!("Failed to enable variable refresh rate, falling back to non-V-Sync.");
-                                sdl2_sys::SDL_GL_SetSwapInterval(0);
-                            }
-                        },
-                    }
-                }
             }
-
-            let platform = Box::new(SDL2GLPlatform(self.refs.clone()));
-            let gl_context: GLContext = GLContext { gles2_mode: false, platform, ctx };
-
-            return Ok(Box::new(OpenGLRenderer::new(gl_context, imgui)));
         }
 
-        {
+        Err(GameError::RenderError("Failed to create any renderer".to_owned()))
-            let mut refs = self.refs.borrow_mut();
-            let window = std::mem::take(&mut refs.window);
-            refs.window = window.make_canvas()?;
-            return Ok(Box::new(SDL2Renderer::new(self.refs.clone(), imgui)?));
-        }
     }
 
     fn as_any(&self) -> &dyn Any {
@@ -563,8 +597,10 @@ struct SDL2Renderer {
 }
 
 impl SDL2Renderer {
+    pub const RENDERER_ID: &'static str = "sdl2";
+
     #[allow(clippy::new_ret_no_self)]
-    pub fn new(refs: Rc<RefCell<SDL2Context>>, mut imgui: imgui::Context) -> GameResult<SDL2Renderer> {
+    pub fn new(refs: Rc<RefCell<SDL2Context>>, mut imgui: imgui::Context) -> GameResult<Box<dyn BackendRenderer>> {
         imgui.set_renderer_name("SDL2Renderer".to_owned());
         let imgui_font_tex = {
             let refs = refs.clone();
@@ -605,7 +641,7 @@ impl SDL2Renderer {
         };
         imgui.fonts().tex_id = TextureId::new(imgui_font_tex.texture.as_ref().unwrap().raw() as usize);
 
-        Ok((SDL2Renderer { refs, imgui: Rc::new(RefCell::new(imgui)), imgui_font_tex }))
+        Ok(Box::new(SDL2Renderer { refs, imgui: Rc::new(RefCell::new(imgui)), imgui_font_tex }))
     }
 }
 

src/framework/backend_winit.rs

@@ -293,48 +293,10 @@ impl BackendEventLoop for WinitEventLoop {
         event_loop.run_app(self);
     }
 
-    fn new_renderer(&self, ctx: *mut Context) -> GameResult<Box<dyn BackendRenderer>> {
+    fn new_renderer(&self) -> GameResult<Box<dyn BackendRenderer>> {
         let mut imgui = init_imgui()?;
         imgui.io_mut().display_size = [640.0, 480.0];
 
-        // let refs = self.refs.clone();
-        // let user_data = Rc::into_raw(refs) as *mut c_void;
-
-        // unsafe fn get_proc_address(user_data: &mut *mut c_void, name: &str) -> *const c_void {
-        //     let refs = Rc::from_raw(*user_data as *mut UnsafeCell<Option<WindowedContext<PossiblyCurrent>>>);
-
-        //     let result = {
-        //         let refs = &mut *refs.get();
-
-        //         if let Some(refs) = refs {
-        //             refs.get_proc_address(name)
-        //         } else {
-        //             std::ptr::null()
-        //         }
-        //     };
-
-        //     *user_data = Rc::into_raw(refs) as *mut c_void;
-
-        //     result
-        // }
-
-        // unsafe fn swap_buffers(user_data: &mut *mut c_void) {
-        //     let refs = Rc::from_raw(*user_data as *mut UnsafeCell<Option<WindowedContext<PossiblyCurrent>>>);
-
-        //     {
-        //         let refs = &mut *refs.get();
-
-        //         if let Some(refs) = refs {
-        //             refs.swap_buffers();
-        //         }
-        //     }
-
-        //     *user_data = Rc::into_raw(refs) as *mut c_void;
-        // }
-
-        // let gl_context = GLContext { gles2_mode: true, is_sdl: false, get_proc_address, swap_buffers, user_data, ctx };
-
-        // Ok(Box::new(OpenGLRenderer::new(gl_context, imgui)))
         Ok(Box::new(super::backend_null::NullRenderer::new(imgui)))
     }
 

src/framework/context.rs

@@ -12,6 +12,7 @@ pub struct Context {
     pub shutdown_requested: bool,
     pub size_hint: (u16, u16),
     pub window_title: String,
+    pub preferred_renderer: Option<String>,
     pub(crate) filesystem: Filesystem,
     pub(crate) renderer: Option<Box<dyn BackendRenderer>>,
     pub(crate) gamepad_context: GamepadContext,
@@ -29,6 +30,7 @@ impl Context {
             shutdown_requested: false,
             size_hint: (640, 480),
             window_title: "Game".to_string(),
+            preferred_renderer: None,
             filesystem: Filesystem::new(),
             renderer: None,
             gamepad_context: GamepadContext::new(),
@@ -43,7 +45,7 @@ impl Context {
     pub fn run(&mut self, game: &mut Game) -> GameResult {
         let backend = init_backend(self.headless, self.size_hint)?;
         let mut event_loop = backend.create_event_loop(self)?;
-        self.renderer = Some(event_loop.new_renderer(self as *mut Context)?);
+        self.renderer = Some(event_loop.new_renderer()?);
 
         event_loop.run(game, self);