DirectX 12

DirectX 12 consumes DXIL (shader model 6) directly, which is convenient because DXC already emits DXIL as an intermediate on other paths — DX12 just carries it through instead of translating to DXBC:

HLSL → DXC → DXIL (SM6)   (consumed directly by MonoGame WindowsDX12)

Current state

The CLI and PlatformTarget accept a DirectX12 profile. Compiling targets MonoGame's WindowsDX12 platform (new in MonoGame 3.8.5, stable since 2026-07-15): the .mgfx uses its own container (profile byte 2), with each shader's DXIL wrapped via DirectX12ShaderCodeWrapper. ShadowDusk's own DX12 output is validated end-to-end against a real mgfxc /platform:WindowsDX12 golden (MonoGame's own 3.8.5 content pipeline) — max Δ 0 across the standard PS/SpriteBatch corpus, a VS-driven rig, and the real-world Apos.Shapes SDF shape renderer (custom vertex shader).

DirectX 12 requires MonoGame 3.8.5+ on the consumer's side (the WindowsDX12 platform didn't exist before). ShadowDusk's own MonoGame reference pin stays at 3.8.2.1105 regardless — targeting DX12 is a choice about the consumer's runtime, the same way choosing Vulkan is.

KNI does not ship a DirectX 12 platform, so this target is MonoGame-only, like Vulkan.

DXIL is signed on every host

Retail D3D12 rejects DXIL whose container hash is zero at pipeline-state creation. DXC signs through dxil.dll, which exists only on Windows, so a non-Windows compile used to emit unsigned DXIL (warned as SD0214, now retired). ShadowDusk now writes the container hash itself, in managed code, on every host: it is Microsoft's open-sourced retail hash (DxilHash.cpp, ComputeHashRetail), pinned byte for byte against dxil.dll's over the fixture corpus, and applied only when dxil.dll has not already signed the container. A Linux or macOS build produces a loadable DX12 effect. Windows on Arm is unchanged: dxil.dll signs there, and a native arm64 DX12 compile is measured byte-identical (signed) to win-x64's (issue #286).

Texture arrays reflect as one parameter (SD0222)

An array of textures (Texture2D Tex[N]) compiles, and the parameter table is exactly what mgfxc 3.8.5's /Profile:DirectX_12 writes (measured for 1, 2 and 4 elements, with and without an explicit register): one Tex parameter bound to the first slot, with the shader header sizing the descriptor range for one texture. In real MonoGame 3.8.5 WindowsDX12 that means effect.Parameters["Tex"] sets element [0] only, and the other elements read as zero even when GraphicsDevice.Textures[i] is set; mgfxc's own build behaves the same (validation/VsDrivenDx12 -- texarr renders both). ShadowDusk keeps that table, so the output stays mgfxc's, and emits the SD0222 warning at the declaration to say so (issue #324). Declare each element as its own texture if every element must be read. A 1-element array is one texture and gets no warning.

(DirectX 11 reflects a texture array the same way since issue #339, one Tex parameter and one record at the array's base slot, measured against mgfxc 3.8.4.1 and 3.8.5; there the other elements ARE read through GraphicsDevice.Textures[i] in real MonoGame WindowsDX, so no warning is raised.)

Sampler arrays are refused (SD0224)

An array of samplers (SamplerState S[N]) is refused by mgfxc on every profile in its own effect parser (Unexpected token '[' found. Expected Semicolon, Comma, or CloseParenthesis.), so no reference output exists for it. ShadowDusk used to compile it on DirectX 11 and 12; it now refuses it with the error SD0224 at the declaration on both (issue #340). Declare each sampler separately and sample through each by name. Vulkan refuses the same shape as SD0221.

A legacy POSITION vertex output works

A vertex shader that writes its clip-space position to the legacy : POSITION0 output (struct VOut { float4 Pos : POSITION0; ... };, the XNA spelling) is mapped to SV_Position on this target, as DirectX 11 does (issue #446, fixed 2026-10-31). Before that, DXC's SM6 path left it an ordinary output and MonoGame threw SEHException (HRESULT 80070057) at draw time; mgfxc's own DirectX 12 build of such a file still throws. Not mapped: POSITION1 and up, a semantic spelled through a macro, and a struct the vertex shader also takes as input; for those, write : SV_POSITION.

Additive by policy

Like all backends, targeting DirectX 12 is opt-in per compile (PlatformTarget.DirectX12) and does not change OpenGL/DX11/v10 output for consumers who don't ask for it.