wgpu/examples/hello-triangle/main.rs

use winit::{
    event::{Event, WindowEvent},
    event_loop::{ControlFlow, EventLoop},
    window::Window,
};

async fn run(event_loop: EventLoop<()>, window: Window, swapchain_format: wgpu::TextureFormat) {
    let size = window.inner_size();
    let instance = wgpu::Instance::new();
    let surface = unsafe { instance.create_surface(&window) };
    let adapter = instance
        .request_adapter(
            &wgpu::RequestAdapterOptions {
                power_preference: wgpu::PowerPreference::Default,
                compatible_surface: Some(&surface),
            },
            wgpu::UnsafeExtensions::disallow(),
            wgpu::BackendBit::PRIMARY,
        )
        .await
        .unwrap();

    let (device, queue) = adapter
        .request_device(
            &wgpu::DeviceDescriptor {
                extensions: wgpu::Extensions::empty(),
                limits: wgpu::Limits::default(),
            },
            None,
        )
        .await
        .unwrap();

    let vs = include_bytes!("shader.vert.spv");
    let vs_module =
        device.create_shader_module(&wgpu::read_spirv(std::io::Cursor::new(&vs[..])).unwrap());

    let fs = include_bytes!("shader.frag.spv");
    let fs_module =
        device.create_shader_module(&wgpu::read_spirv(std::io::Cursor::new(&fs[..])).unwrap());

    let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
        bind_group_layouts: &[],
    });

    let render_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
        layout: &pipeline_layout,
        vertex_stage: wgpu::ProgrammableStageDescriptor {
            module: &vs_module,
            entry_point: "main",
        },
        fragment_stage: Some(wgpu::ProgrammableStageDescriptor {
            module: &fs_module,
            entry_point: "main",
        }),
        rasterization_state: Some(wgpu::RasterizationStateDescriptor {
            front_face: wgpu::FrontFace::Ccw,
            cull_mode: wgpu::CullMode::None,
            depth_bias: 0,
            depth_bias_slope_scale: 0.0,
            depth_bias_clamp: 0.0,
        }),
        primitive_topology: wgpu::PrimitiveTopology::TriangleList,
        color_states: &[wgpu::ColorStateDescriptor {
            format: swapchain_format,
            color_blend: wgpu::BlendDescriptor::REPLACE,
            alpha_blend: wgpu::BlendDescriptor::REPLACE,
            write_mask: wgpu::ColorWrite::ALL,
        }],
        depth_stencil_state: None,
        vertex_state: wgpu::VertexStateDescriptor {
            index_format: wgpu::IndexFormat::Uint16,
            vertex_buffers: &[],
        },
        sample_count: 1,
        sample_mask: !0,
        alpha_to_coverage_enabled: false,
    });

    let mut sc_desc = wgpu::SwapChainDescriptor {
        usage: wgpu::TextureUsage::OUTPUT_ATTACHMENT,
        format: swapchain_format,
        width: size.width,
        height: size.height,
        present_mode: wgpu::PresentMode::Mailbox,
    };

    let mut swap_chain = device.create_swap_chain(&surface, &sc_desc);

    event_loop.run(move |event, _, control_flow| {
        // force ownership by the closure
        let _ = (
            &instance,
            &adapter,
            &vs_module,
            &fs_module,
            &pipeline_layout,
        );

        *control_flow = ControlFlow::Poll;
        match event {
            Event::WindowEvent {
                event: WindowEvent::Resized(size),
                ..
            } => {
                sc_desc.width = size.width;
                sc_desc.height = size.height;
                swap_chain = device.create_swap_chain(&surface, &sc_desc);
            }
            Event::RedrawRequested(_) => {
                let frame = swap_chain
                    .get_next_frame()
                    .expect("Failed to acquire next swap chain texture")
                    .output;
                let mut encoder =
                    device.create_command_encoder(&wgpu::CommandEncoderDescriptor { label: None });
                {
                    let mut rpass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                        color_attachments: &[wgpu::RenderPassColorAttachmentDescriptor {
                            attachment: &frame.view,
                            resolve_target: None,
                            load_op: wgpu::LoadOp::Clear,
                            store_op: wgpu::StoreOp::Store,
                            clear_color: wgpu::Color::GREEN,
                        }],
                        depth_stencil_attachment: None,
                    });
                    rpass.set_pipeline(&render_pipeline);
                    rpass.draw(0..3, 0..1);
                }

                queue.submit(Some(encoder.finish()));
            }
            Event::WindowEvent {
                event: WindowEvent::CloseRequested,
                ..
            } => *control_flow = ControlFlow::Exit,
            _ => {}
        }
    });
}

fn main() {
    let event_loop = EventLoop::new();
    let window = winit::window::Window::new(&event_loop).unwrap();
    #[cfg(not(target_arch = "wasm32"))]
    {
        env_logger::init();
        // Temporarily avoid srgb formats for the swapchain on the web
        futures::executor::block_on(run(event_loop, window, wgpu::TextureFormat::Bgra8UnormSrgb));
    }
    #[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(event_loop, window, wgpu::TextureFormat::Bgra8Unorm));
    }
}