Struct GpuContext 

pub struct GpuContext {
    pub device: Device,
    pub queue: Queue,
    pub color_texture: Texture,
    pub color_view: TextureView,
    pub width: u32,
    pub height: u32,
    pub sample_count: u32,
    pub msaa_view: Option<TextureView>,
}

An initialised headless GPU context: device, queue, and an offscreen colour texture (plus its view) sized to the requested surface.

No window or swap-chain surface is involved — rendering goes to the offscreen texture, which can then be read back to CPU memory with crate::gpu::renderer’s readback path.

Fields

device: Device

The logical GPU device.

queue: Queue

The command queue for the device.

color_texture: Texture

The offscreen colour texture (RENDER_ATTACHMENT | COPY_SRC). This is always the resolve/readback target (sample_count=1).

color_view: TextureView

A default view over color_texture. When MSAA is active this is the resolve target; when no MSAA it is the direct render target.

width: u32

Target width in physical pixels.

height: u32

Target height in physical pixels.

sample_count: u32

The effective MSAA sample count (1 = no MSAA, 4 or 8 = MSAA).

msaa_view: Option<TextureView>

The MSAA multisample texture view, present only when sample_count > 1.

Implementations

impl GpuContext

pub fn headless_with_sample_count( width: u32, height: u32, requested: u32, ) -> Result<Self, UiError>

Initialise a headless GPU context with an offscreen target of width × height pixels and the specified MSAA sample count.

The requested sample count is validated against adapter capabilities. If the adapter does not support the requested count, sample_count=1 (no MSAA) is used instead. Only 4 and 8 are recognised as valid MSAA counts; anything else silently falls back to 1.

Errors

• UiError::Unsupported — no GPU adapter is available, or the requested target dimensions are zero.
• UiError::Backend — the adapter was found but the device request failed.

pub fn headless(width: u32, height: u32) -> Result<Self, UiError>

Initialise a headless GPU context with an offscreen target of width × height pixels without MSAA (sample_count=1).

This delegates to headless_with_sample_count with requested=1, preserving the exact same code path as before MSAA support was added.

Errors

• UiError::Unsupported — no GPU adapter is available (the caller should treat this as “skip”, not a hard failure), or the requested target dimensions are zero.
• UiError::Backend — the adapter was found but the device request failed.

pub fn color_attachment(&self) -> (&TextureView, Option<&TextureView>)

Returns the colour attachment view and optional resolve target.

Under MSAA (sample_count > 1): render into msaa_view, resolve into color_view. Under no MSAA (sample_count == 1): render directly into color_view, no resolve.

pub fn sample_count(&self) -> u32

Returns the effective MSAA sample count (1 = no MSAA, 4 or 8 = MSAA).

pub fn resize(&mut self, new_width: u32, new_height: u32) -> Result<(), UiError>

Resize the offscreen colour target to new_width × new_height pixels.

Recreates only the colour texture and its view (and the MSAA texture if active). The device, queue, and sample count are preserved.

Errors

Returns UiError::Unsupported if either dimension is zero.