D3D9On12 is a mapping layer that maps graphics commands from Direct X 9 to DirectX 12. D3D9On12 is not an implementation of the Direct X API, but an implementation of the D3D9 usermode DDI (Device Driver Interface). This means that it is not a binary named d3d9.dll, but d3d9on12.dll.

When an application creates a D3D9 device, they may choose it to be a D3D9On12 device instead of a native D3D9 device. When this happens, d3d9on12.dll is loaded and initialized by the D3D9 runtime. When an application calls rendering commands, D3D9 validates these commands, then converts them to D3D9’s DDI and sends them to D3D9On12, just like any D3D9 driver. D3D9On12 will receive these commands and translate them into D3D12 API calls, which are further validated by the D3D12 runtime, optionally including the D3D12 debug layer, and then translated into D3D12 DDIs and sent to the D3D12 driver.

Construct

In order to build D3D9On12, the WDK (Windows Driver Kit) must be installed to provide D3D9On12 with d3d10umddi.h and to generate the D3D12TranslationLayer_WDK project, which hosts some code needed to parse DXBC shaders and containers. If D3D12TranslationLayer and its subprojects D3D12TranslationLayer_WDK and DXBCParser are not already included, D3D12TranslationLayer_WDK will be fetched from GitHub when building with CMake. DxbcSigner.dll will be automatically pulled from NuGet.

compatibility

If possible, we will try to maintain compatibility between D3D9 and D3D9On12.