wgpu/examples/framework.rs

use std::time;
use winit::{
    event::{self, WindowEvent},
    event_loop::{ControlFlow, EventLoop},
    window::Window,
};

#[cfg_attr(rustfmt, rustfmt_skip)]
#[allow(unused)]
pub const OPENGL_TO_WGPU_MATRIX: cgmath::Matrix4<f32> = cgmath::Matrix4::new(
    1.0, 0.0, 0.0, 0.0,
    0.0, 1.0, 0.0, 0.0,
    0.0, 0.0, 0.5, 0.0,
    0.0, 0.0, 0.5, 1.0,
);

#[allow(dead_code)]
pub fn cast_slice<T>(data: &[T]) -> &[u8] {
    use std::mem::size_of;
    use std::slice::from_raw_parts;

    unsafe { from_raw_parts(data.as_ptr() as *const u8, data.len() * size_of::<T>()) }
}

#[allow(dead_code)]
pub enum ShaderStage {
    Vertex,
    Fragment,
    Compute,
}

pub trait Example: 'static + Sized {
    fn init(
        sc_desc: &wgpu::SwapChainDescriptor,
        device: &wgpu::Device,
    ) -> (Self, Option<wgpu::CommandBuffer>);
    fn resize(
        &mut self,
        sc_desc: &wgpu::SwapChainDescriptor,
        device: &wgpu::Device,
        queue: &wgpu::Queue,
    );
    fn update(&mut self, event: WindowEvent);
    fn render(
        &mut self,
        frame: &wgpu::SwapChainOutput,
        device: &wgpu::Device,
        queue: &wgpu::Queue,
    ) -> wgpu::CommandBuffer;
}

async fn run_async<E: Example>(event_loop: EventLoop<()>, window: Window) {
    log::info!("Initializing the surface...");

    let instance = wgpu::Instance::new();
    let (size, surface) = unsafe {
        let size = window.inner_size();
        let surface = instance.create_surface(&window);
        (size, surface)
    };

    let adapter = instance
        .request_adapter(
            &wgpu::RequestAdapterOptions {
                power_preference: wgpu::PowerPreference::Default,
                compatible_surface: Some(&surface),
            },
            wgpu::BackendBit::PRIMARY,
        )
        .await
        .unwrap();

    let trace_dir = std::env::var("WGPU_TRACE");
    let (device, queue) = adapter
        .request_device(
            &wgpu::DeviceDescriptor {
                extensions: wgpu::Extensions {
                    anisotropic_filtering: false,
                },
                limits: wgpu::Limits::default(),
            },
            match trace_dir {
                Ok(ref value) if !cfg!(feature = "trace") => {
                    log::error!("Unable to trace into {:?} without \"trace\" feature enabled!", value);
                    None
                }
                Ok(ref value) => Some(std::path::Path::new(value)),
                Err(_) => None,
            },
        )
        .await
        .unwrap();

    let mut sc_desc = wgpu::SwapChainDescriptor {
        usage: wgpu::TextureUsage::OUTPUT_ATTACHMENT,
        // TODO: Allow srgb unconditionally
        format: if cfg!(target_arch = "wasm32") {
            wgpu::TextureFormat::Bgra8Unorm
        } else {
            wgpu::TextureFormat::Bgra8UnormSrgb
        },
        width: size.width,
        height: size.height,
        present_mode: wgpu::PresentMode::Mailbox,
    };
    let mut swap_chain = device.create_swap_chain(&surface, &sc_desc);

    log::info!("Initializing the example...");
    let (mut example, init_command_buf) = E::init(&sc_desc, &device);
    if init_command_buf.is_some() {
        queue.submit(init_command_buf);
    }

    #[cfg(not(target_arch = "wasm32"))]
    let mut last_update_inst = time::Instant::now();

    log::info!("Entering render loop...");
    event_loop.run(move |event, _, control_flow| {
        let _ = (&instance, &adapter); // force ownership by the closure
        *control_flow = if cfg!(feature = "metal-auto-capture") {
            ControlFlow::Exit
        } else {
            #[cfg(not(target_arch = "wasm32"))]
            {
                ControlFlow::WaitUntil(time::Instant::now() + time::Duration::from_millis(10))
            }
            #[cfg(target_arch = "wasm32")]
            {
                ControlFlow::Poll
            }
        };
        match event {
            event::Event::MainEventsCleared => {
                #[cfg(not(target_arch = "wasm32"))]
                {
                    if last_update_inst.elapsed() > time::Duration::from_millis(20) {
                        window.request_redraw();
                        last_update_inst = time::Instant::now();
                    }
                }

                #[cfg(target_arch = "wasm32")]
                window.request_redraw();
            }
            event::Event::WindowEvent {
                event: WindowEvent::Resized(size),
                ..
            } => {
                log::info!("Resizing to {:?}", size);
                sc_desc.width = size.width;
                sc_desc.height = size.height;
                swap_chain = device.create_swap_chain(&surface, &sc_desc);
                example.resize(&sc_desc, &device, &queue);
            }
            event::Event::WindowEvent { event, .. } => match event {
                WindowEvent::KeyboardInput {
                    input:
                        event::KeyboardInput {
                            virtual_keycode: Some(event::VirtualKeyCode::Escape),
                            state: event::ElementState::Pressed,
                            ..
                        },
                    ..
                }
                | WindowEvent::CloseRequested => {
                    *control_flow = ControlFlow::Exit;
                }
                _ => {
                    example.update(event);
                }
            },
            event::Event::RedrawRequested(_) => {
                let frame = swap_chain
                    .get_next_texture()
                    .expect("Timeout when acquiring next swap chain texture");
                let command_buf = example.render(&frame, &device, &queue);
                queue.submit(Some(command_buf));
            }
            _ => {}
        }
    });
}

pub fn run<E: Example>(title: &str) {
    let event_loop = EventLoop::new();
    let mut builder = winit::window::WindowBuilder::new();
    builder = builder.with_title(title);
    #[cfg(windows_OFF)] //TODO
    {
        use winit::platform::windows::WindowBuilderExtWindows;
        builder = builder.with_no_redirection_bitmap(true);
    }
    let window = builder.build(&event_loop).unwrap();

    #[cfg(not(target_arch = "wasm32"))]
    {
        env_logger::init();
        futures::executor::block_on(run_async::<E>(event_loop, window));
    }
    #[cfg(target_arch = "wasm32")]
    {
        std::panic::set_hook(Box::new(console_error_panic_hook::hook));
        console_log::init().expect("could not initialize logger");
        use winit::platform::web::WindowExtWebSys;
        // On wasm, append the canvas to the document body
        web_sys::window()
            .and_then(|win| win.document())
            .and_then(|doc| doc.body())
            .and_then(|body| {
                body.append_child(&web_sys::Element::from(window.canvas()))
                    .ok()
            })
            .expect("couldn't append canvas to document body");
        wasm_bindgen_futures::spawn_local(run_async::<E>(event_loop, window));
    }
}

// This allows treating the framework as a standalone example,
// thus avoiding listing the example names in `Cargo.toml`.
#[allow(dead_code)]
fn main() {}