Direct3D 12 driver

The D3D12 driver maps RD's resource, command, and synchronization contracts to Direct3D 12 and DXGI. It is shared by Forward+ and Mobile through RD; it does not supply another scene rendering method.

Context and device

RenderingContextDriverD3D12 supplies adapter/device discovery, Windows surface data, debug support, and device-driver construction. The Windows display server selects this context and can try another compiled driver according to fallback settings.

RenderingDeviceDriverD3D12 creates the device and checks required features, shader capabilities, formats, and limits. It creates resources with D3D12 Memory Allocator, and translates RD usage/binding descriptions to native resource and descriptor representations.

The header's native helper types, allocation records, descriptors, command structures, and state trackers are part of that translation. They are not additional scene APIs. Their purpose includes adapting an RD contract that does not map one-to-one to D3D12 state.

Resource binding and shaders

RenderingShaderContainerD3D12 converts SPIR-V to NIR and DXIL when the NIR compilation path is built. It generates resource-binding/root-signature data and retains specialization metadata needed by pipeline creation. DXIL patching and signing helpers also live with the shader-container implementation.

This path requires coordination among shader reflection, RD uniform sets, descriptor tables, and native root parameters. Changing one set/binding convention can affect all four representations.

Graphics and compute pipelines consume the generated shader data together with RD pipeline state. A method's shader can consequently compile through the shared engine language and GLSL stages before reaching D3D12-specific conversion and pipeline creation.

Command execution

The driver maps command queues, allocators/lists, barriers, copy operations, draws, dispatches, fences, and swapchains to D3D12/DXGI. Queue execution calls ExecuteCommandLists; presentation uses the DXGI swapchain's Present().

RD manages frame-level resource retirement and the high-level dependency graph. The driver translates the required access/resource state changes into native operations. RD RIDs and D3D12 resource pointers must remain distinct when inspecting a transfer or descriptor problem.

Cache limitation

pipeline_cache_create() warns that PSO caching is not implemented and returns false. The corresponding free/query/serialize methods report unimplemented operations. This describes the native persistent pipeline-cache interface. It does not disable ShaderRD bytecode caching or live RD pipeline reuse.

Implementing persistent PSO caching is a possible future project, but it needs cache compatibility, device/driver invalidation, failure recovery, and Windows measurements. It is not established as a small performance fix by the stub alone.

External integration

D3D12Hooks supports graphics interoperation used by the OpenXR platform extension. This puts device initialization and graphics binding under a cross-subsystem contract. Engine changes must preserve that setup order even when no scene-level XR code appears in the edited driver function.

ANGLE's Compatibility route is separate: it does not execute through this Redot D3D12 device driver.

Sources: D3D12 entry points, Windows selection, and cache limitation.