| # Adapter Options (Unstable!) |
| |
| `wgpu::RequestAdapterOptions` may be passed to `wgpuInstanceRequestAdapter` to request an adapter. |
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| Dawn provides a few chained extension structs on `RequestAdapterOptions` to customize the behavior. |
| Currently, the `WGPUInstance` doesn't provide a way to query support for these features, so these |
| features may not be suitable for general use yet. Currently, they are used in Dawn's testing, and |
| in Chromium-specific integration with Dawn. |
| |
| `DawnTogglesDescriptor` can also be chained on `RequestAdapterOptions` to provide the required adapter toggles. However, the final adapter toggles state also depends on instance toggles inheritance and adapter toggles validation/default-setting. |
| |
| `dawn::native::Instance::EnumerateAdapters` is a Dawn native-only API that may be used to synchronously |
| get a list of adapters according to the RequestAdapterOptions. The members are treated as follows: |
| - `RequestAdapterOptions::compatibleSurface` is ignored. |
| - `RequestAdapterOptions::powerPreference` adapters are sorted according to powerPreference such that |
| preferred adapters are at the front of the list. It is a preference - so if |
| wgpu::PowerPreference::LowPower is passed, the list may contain only integrated GPUs, fallback adapters, or a mix of everything. Implementations *should* try to avoid returning any discrete GPUs when low power is requested if at least one integrated GPU is available. |
| - `RequestAdapterOptions::backendType` filters adapters such that only those on a particular backend are discovered. If `WGPURequestAdapterType_Undefined` is passed, all backends may be discovered. |
| - `RequestAdapterOptions::compatibilityMode` all returned adapters must match the requested compatibility mode. |
| - `RequestAdapterOptions::forceFallbackAdapter` all returned adapters must be fallback adapters. |
| |
| If no options are passed to EnumerateAdapters, then it is as if the default `RequestAdapterOptions` are passed. |
| |
| ### `RequestAdapterOptionsGetGLProc` |
| |
| When discovering adapters on the GL backend, Dawn uses the provided `RequestAdapterOptionsGetGLProc::getProc` method to load GL procs. This extension struct does nothing on other backends. |
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| ### `RequestAdapterOptionsLUID` |
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| When discovering adapters on D3D11 and D3D12, Dawn only discovers adapters matching the provided `RequestAdapterOptionsLUID::adapterLUID`. This extension struct does nothing on other backends. |
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| ### `DawnTogglesDescriptor` |
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| When discovering adapters, Dawn will use chained `DawnTogglesDescriptor` as required adapter |
| toggles. The final toggles state of each result adapter depends on the inheritance of instance |
| toggles state, the backend-specific validation and the backend-specific default setting. |
