为何我的wgpu绑定组仅支持单个Texture绑定？

原本仅包含单个Texture绑定的BindGroup和BindGroupLayout可正常用于后处理渲染：

let bind_group_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
    label: None,
    entries: &[wgpu::BindGroupLayoutEntry {
        binding: 0,
        visibility: wgpu::ShaderStages::FRAGMENT,
        ty: wgpu::BindingType::Texture {
            sample_type: wgpu::TextureSampleType::Float { filterable: true },
            view_dimension: wgpu::TextureViewDimension::D2,
            multisampled: false,
        },
        count: None,
    }],
});

let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
    label: None,
    entries: &[wgpu::BindGroupEntry {
        binding: 0,
        resource: wgpu::BindingResource::TextureView(&target),
    }],
    layout: &bind_group_layout,
});

之后添加Sampler并更新绑定组布局和绑定组：

// 创建Sampler
let linear_sampler = device.create_sampler(&wgpu::SamplerDescriptor {
    mag_filter: wgpu::FilterMode::Nearest,
    min_filter: wgpu::FilterMode::Nearest,
    mipmap_filter: wgpu::FilterMode::Nearest,
    ..Default::default()
});

// 更新后的BindGroupLayout和BindGroup
let bind_group_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
    label: None,
    entries: &[
        wgpu::BindGroupLayoutEntry {
            binding: 0,
            visibility: wgpu::ShaderStages::FRAGMENT,
            ty: wgpu::BindingType::Texture {
                sample_type: wgpu::TextureSampleType::Float { filterable: true },
                view_dimension: wgpu::TextureViewDimension::D2,
                multisampled: false,
            },
            count: None,
        },
        wgpu::BindGroupLayoutEntry {
            binding: 1,
            visibility: wgpu::ShaderStages::FRAGMENT,
            ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::NonFiltering),
            count: None,
        },
    ],
});

let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
    label: None,
    entries: &[
        wgpu::BindGroupEntry {
            binding: 0,
            resource: wgpu::BindingResource::TextureView(&target),
        },
        wgpu::BindGroupEntry {
            binding: 1,
            resource: wgpu::BindingResource::Sampler(&linear_sampler),
        },
    ],
    layout: &bind_group_layout,
});

运行后触发ValidationError：

thread 'main' panicked at 'wgpu error: Validation Error

Caused by:
    In a RenderPass
      note: encoder = `<CommandBuffer-(0, 2, Metal)>`
    In a draw command, indexed:false indirect:false
      note: render pipeline = `<RenderPipeline-(1, 1, Metal)>`
    the pipeline layout, associated with the current render pipeline, contains a bind group layout at index 0 which is incompatible with the bind group layout associated with the bind group at 0

该问题在Metal和DirectX 12环境下均会出现，且仅添加单个Sampler或第二个Texture时也会触发相同错误。仅绑定单个Texture的配置可正常工作，请问原因是什么？

核心原因是你更新了BindGroup和BindGroupLayout，但没有同步更新渲染管线（RenderPipeline）所依赖的管线布局（PipelineLayout）。

wgpu的验证规则要求：绑定到RenderPass的BindGroup，其BindGroupLayout必须和当前使用的RenderPipeline对应的PipelineLayout中同索引的BindGroupLayout完全匹配。你修改了BindGroupLayout，但RenderPipeline仍然使用旧的、仅包含单个Texture的BindGroupLayout构建的PipelineLayout，导致两者不兼容，触发验证错误。

修复步骤：

1. 同步更新PipelineLayout：创建RenderPipeline时，确保使用的PipelineLayout是基于新的BindGroupLayout创建的，而不是旧的实例。例如：

// 用新的bind_group_layout创建管线布局
let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
    label: None,
    bind_group_layouts: &[&bind_group_layout], // 这里必须是更新后的布局
    push_constant_ranges: &[],
});

// 用新的pipeline_layout创建渲染管线
let render_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
    layout: Some(&pipeline_layout),
    // 其他配置...
});

2. 同步更新着色器代码：确保WSL着色器中声明的绑定数量、索引和类型和Rust代码中的BindGroupLayout完全对应。例如新增的sampler对应binding=1，着色器中要正确声明：

@group(0) @binding(0) var input_tex: texture_2d<f32>;
@group(0) @binding(1) var input_sampler: sampler;

内容的提问来源于stack exchange，提问作者frankenapps