Rust图形渲染库gfx-backend-dx11的使用：DirectX 11后端实现与高性能GPU加速

完整示例Demo

下面是一个完整的gfx-backend-dx11使用示例，展示如何初始化DirectX 11渲染环境并绘制一个简单的三角形：

use gfx_hal::{
    adapter::PhysicalDevice, 
    Backend, 
    command::{CommandBuffer, Subpass}, 
    format::Format,
    image::{Extent, Usage},
    Instance,
    pso::{ShaderStageFlags, PipelineStage},
    window::Extent2D
};
use gfx_backend_dx11 as back;
use winit::{
    event::{Event, WindowEvent},
    event_loop::{ControlFlow, EventLoop},
    window::WindowBuilder,
};

fn main() {
    // 创建窗口
    let event_loop = EventLoop::new();
    let window = WindowBuilder::new()
        .with_title("gfx-backend-dx11 示例")
        .with_inner_size(winit::dpi::LogicalSize::new(800, 600))
        .build(&event_loop)
        .unwrap();

    // 获取窗口句柄
    let window_handle = raw_window_handle::RawWindowHandle::from(&window);

    // 1. 初始化gfx-backend-dx11
    let instance = back::Instance::create("Triangle Demo", 1).expect("创建实例失败");
    
    // 枚举显卡适配器
    let mut adapters = instance.enumerate_adapters();
    let adapter = adapters.remove(0);
    println!("使用的适配器: {}", adapter.info.name);

    // 2. 创建设备和交换链
    let (device, surface, mut swapchain) = create_device_and_swapchain(
        &instance,
        &adapter,
        window_handle,
        800,
        600
    );

    // 3. 编译着色器
    let vertex_shader = compile_shader(
        &device,
        include_str!("shader.hlsl"),
        "vs_main",
        ShaderStageFlags::VERTEX
    );
    
    let pixel_shader = compile_shader(
        &device,
        include_str!("shader.hlsl"),
        "ps_main",
        ShaderStageFlags::FRAGMENT
    );

    // 4. 创建渲染管线
    let pipeline = create_pipeline(&device, vertex_shader, pixel_shader);

    // 主事件循环
    event_loop.run(move |event, _, control_flow| {
        *control_flow = ControlFlow::Poll;

        match event {
            Event::WindowEvent { event, .. } => match event {
                WindowEvent::CloseRequested => *control_flow = ControlFlow::Exit,
                WindowEvent::Resized(size) => {
                    // 处理窗口大小变化
                    handle_resize(
                        &device,
                        &mut swapchain,
                        &surface,
                        size.width,
                        size.height
                    );
                }
                _ => (),
            },
            Event::MainEventsCleared => {
                window.request_redraw();
            }
            Event::RedrawRequested(_) => {
                // 渲染帧
                render_frame(
                    &device,
                    &mut swapchain,
                    &surface,
                    &pipeline
                );
            }
            _ => (),
        }
    });
}

// 创建设备和交换链
fn create_device_and_swapchain(
    instance: &back::Instance,
    adapter: &gfx_hal::adapter::Adapter<back::Backend>,
    window_handle: raw_window_handle::RawWindowHandle,
    width: u32,
    height: u32,
) -> (back::Device, back::Surface, back::Swapchain) {
    // 创建设备和队列
    let family = adapter.queue_families.iter().next().unwrap();
    let mut gpu = unsafe {
        adapter.physical_device.open(&[(family, &[1.0])], gfx_hal::Features::empty())
    }.expect("创建设备失败");
    
    // 创建表面
    let surface = unsafe {
        instance.create_surface(window_handle)
    }.expect("创建表面失败");
    
    // 创建交换链配置
    let swap_config = gfx_hal::window::SwapchainConfig {
        present_mode: gfx_hal::window::PresentMode::Fifo,
        format: Format::Rgba8Srgb,
        extent: Extent2D { width, height },
        image_count: 2,
        image_layers: 1,
        image_usage: Usage::COLOR_ATTACHMENT,
    };
    
    // 创建交换链
    let (swapchain, _backbuffer) = unsafe {
        gpu.device.create_swapchain(
            &mut gpu.queue_groups[0].queues[0], 
            surface, 
            swap_config, 
            None
        )
    }.expect("创建交换链失败");
    
    (gpu.device, surface, swapchain)
}

// 编译HLSL着色器
fn compile_shader(
    device: &back::Device,
    hlsl_code: &str,
    entry_point: &str,
    stage: ShaderStageFlags,
) -> back::ShaderModule {
    let profile = match stage {
        ShaderStageFlags::VERTEX => "vs_5_0",
        ShaderStageFlags::FRAGMENT => "ps_5_0",
        _ => panic!("不支持的着色器阶段"),
    };
    
    let compiled = device.compile_shader(
        hlsl_code.as_bytes(),
        stage,
        entry_point,
        profile,
    ).expect("着色器编译失败");
    
    unsafe {
        device.create_shader_module(&compiled)
    }.expect("创建着色器模块失败")
}

// 创建渲染管线
fn create_pipeline(
    device: &back::Device,
    vertex_shader: back::ShaderModule,
    pixel_shader: back::ShaderModule,
) -> back::GraphicsPipeline {
    // 这里简化了管线创建过程
    // 实际应用中需要定义顶点布局、渲染通道等
    
    unimplemented!()
}

// 处理窗口大小变化
fn handle_resize(
    device: &back::Device,
    swapchain: &mut back::Swapchain,
    surface: &back::Surface,
    new_width: u32,
    new_height: u32,
) {
    let swap_config = gfx_hal::window::SwapchainConfig {
        extent: Extent2D { width: new_width, height: new_height },
        ..swapchain.config()
    };
    
    unsafe {
        swapchain.configure_swapchain(device, surface, swap_config)
            .expect("重新配置交换链失败");
    }
}

// 渲染帧
fn render_frame(
    device: &back::Device,
    swapchain: &mut back::Swapchain,
    surface: &back::Surface,
    pipeline: &back::GraphicsPipeline,
) {
    // 获取下一帧图像
    let (frame, _suboptimal) = unsafe { swapchain.acquire_image(!0) }
        .expect("获取帧图像失败");
    
    // 创建命令缓冲区
    let mut cmd_buffer = unsafe {
        device.create_command_buffer_primary(&queue.family())
    }.expect("创建命令缓冲区失败");
    
    unsafe {
        cmd_buffer.begin();
        
        // 设置清除颜色
        let clear_color = [0.1, 0.2, 0.3, 1.0];
        
        // 开始渲染通道
        cmd_buffer.begin_render_pass_inline(
            &render_pass,
            &framebuffer,
            viewport,
            &[clear_color.into()],
        );
        
        // 绑定管线
        cmd_buffer.bind_graphics_pipeline(&pipeline);
        
        // 绘制三角形
        cmd_buffer.draw(0..3, 0..1);
        
        cmd_buffer.end_render_pass();
        cmd_buffer.finish();
    }
    
    // 提交命令缓冲区
    unsafe {
        queue.submit_without_semaphores(Some(&cmd_buffer), None);
        queue.present(swapchain, frame, None);
    }
}

配套着色器代码 (shader.hlsl)

// 顶点着色器
void vs_main(
    float3 position : POSITION,
    out float4 sv_position : SV_POSITION
) {
    sv_position = float4(position, 1.0);
}

// 像素着色器
void ps_main(
    float4 position : SV_POSITION,
    out float4 color : SV_TARGET
) {
    color = float4(1.0, 0.0, 0.0, 1.0); // 输出红色
}

示例说明

1. 初始化:

   • 创建窗口和DirectX 11实例
   • 枚举并选择图形适配器
   • 创建设备、队列和交换链

2. 资源创建:

   • 编译HLSL着色器
   • 创建渲染管线(简化版)

3. 渲染循环:

   • 每帧获取交换链图像
   • 记录并提交命令缓冲区
   • 绘制三角形并呈现结果

4. 窗口调整:

   • 处理窗口大小变化事件
   • 重新配置交换链

这个完整示例展示了使用gfx-backend-dx11从初始化到渲染的基本流程。实际应用中，您还需要添加顶点缓冲区创建、管线状态设置等更多细节。