gfx-rs/wgpu · error

{:?} is not enabled for this backend

Error message

{:?} is not enabled for this backend

What it means

DX12 only supports Fill and Wireframe fill modes. When a render pipeline is created with PolygonMode::Point, the backend's map_polygon_mode panics because there is no D3D12 equivalent. Normally wgpu-core rejects POLYGON_MODE_POINT unless the feature is enabled, so this panic means a point polygon mode reached the DX12 backend unvalidated.

Source

Thrown at wgpu-hal/src/dx12/conv.rs:254

            Direct3D12::D3D12_PRIMITIVE_TOPOLOGY_TYPE_LINE,
            Direct3D::D3D_PRIMITIVE_TOPOLOGY_LINESTRIP,
        ),
        wgt::PrimitiveTopology::TriangleList => (
            Direct3D12::D3D12_PRIMITIVE_TOPOLOGY_TYPE_TRIANGLE,
            Direct3D::D3D_PRIMITIVE_TOPOLOGY_TRIANGLELIST,
        ),
        wgt::PrimitiveTopology::TriangleStrip => (
            Direct3D12::D3D12_PRIMITIVE_TOPOLOGY_TYPE_TRIANGLE,
            Direct3D::D3D_PRIMITIVE_TOPOLOGY_TRIANGLESTRIP,
        ),
    }
}

pub fn map_polygon_mode(mode: wgt::PolygonMode) -> Direct3D12::D3D12_FILL_MODE {
    match mode {
        wgt::PolygonMode::Fill => Direct3D12::D3D12_FILL_MODE_SOLID,
        wgt::PolygonMode::Line => Direct3D12::D3D12_FILL_MODE_WIREFRAME,
        wgt::PolygonMode::Point => panic!(
            "{:?} is not enabled for this backend",
            wgt::Features::POLYGON_MODE_POINT
        ),
    }
}

/// D3D12 doesn't support passing factors ending in `_COLOR` for alpha blending
/// (see <https://learn.microsoft.com/en-us/windows/win32/api/d3d12/ns-d3d12-d3d12_render_target_blend_desc>).
/// Therefore this function takes an additional `is_alpha` argument
/// which if set will return an equivalent `_ALPHA` factor.
fn map_blend_factor(factor: wgt::BlendFactor, is_alpha: bool) -> Direct3D12::D3D12_BLEND {
    use wgt::BlendFactor as Bf;
    match factor {
        Bf::Zero => Direct3D12::D3D12_BLEND_ZERO,
        Bf::One => Direct3D12::D3D12_BLEND_ONE,
        Bf::Src if is_alpha => Direct3D12::D3D12_BLEND_SRC_ALPHA,
        Bf::Src => Direct3D12::D3D12_BLEND_SRC_COLOR,
        Bf::OneMinusSrc if is_alpha => Direct3D12::D3D12_BLEND_INV_SRC_ALPHA,

View on GitHub (pinned to 3e11ff59bf)

Solutions

1. Request Features::POLYGON_MODE_POINT in DeviceDescriptor::required_features — note many DX12 devices do not expose it; check adapter.features() first.
2. Switch the pipeline to PolygonMode::Line or Fill and render points via point-list topology or instanced quads instead.
3. Create a fallback pipeline for backends that lack POLYGON_MODE_POINT.

Example fix

// before
let pipeline = device.create_render_pipeline(&RenderPipelineDescriptor {
    primitive: PrimitiveState { polygon_mode: PolygonMode::Point, ..Default::default() },
    ..Default::default()
});
// after
let polygon_mode = if device.features().contains(wgpu::Features::POLYGON_MODE_POINT) {
    PolygonMode::Point
} else {
    PolygonMode::Line // fallback for DX12
};
let pipeline = device.create_render_pipeline(&RenderPipelineDescriptor {
    primitive: PrimitiveState { polygon_mode, ..Default::default() },
    ..Default::default()
});

let mode = if device.features().contains(wgpu::Features::POLYGON_MODE_POINT) {
    PolygonMode::Point
} else { PolygonMode::Fill };

fn supports_point_mode(d: &wgpu::Device) -> bool {
    d.features().contains(wgpu::Features::POLYGON_MODE_POINT)
}

When it happens

Trigger: Creating a RenderPipeline with primitive.polygon_mode = PolygonMode::Point on the DX12 backend without Features::POLYGON_MODE_POINT in required_features; porting Vulkan/desktop code that uses point rasterization directly to wgpu on DX12.

Common situations: Debug visualization pipelines that draw points via polygon mode; apps developed on Metal/Vulkan (where POLYGON_MODE_POINT exists) run on Windows/DX12 where the feature is unsupported.

Related errors

• Feature `MESH_SHADING` not enabled
• Attempted to create a static DXC shader compiler, but the st
• wgpu-hal invariant was violated (usage error): {txt}
• wgpu-hal ran into a preventable internal error: {txt}
• {:?} is not enabled for this backend

AI-assisted analysis of gfx-rs/wgpu@3e11ff59bf (2026-09-03). Data as JSON: /api/errors/932304829300e1e2. Report an issue: GitHub.