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gpu: D3D12 only requires feature level 11_0 with Resource Binding Tier 2.

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We previously thought this wasn't possible because constant buffer offsets and
partial updates were unavailable, but we were reading the wrong table - this is
only the case for D3D11...

https://learn.microsoft.com/en-us/windows/win32/direct3d11/overviews-direct3d-11-devices-downlevel-intro

... while 12 doesn't list this feature at all:

https://learn.microsoft.com/en-us/windows/win32/direct3d12/hardware-feature-levels

We double checked and Jesse Natalie confirmed that this feature is required for
D3D12 even for 11_0 drivers. (Thanks Jesse!)

Additionally, D3D12 requires that UAVs are accessible from all shader stages,
meaning Tier 2 is enough to support the number of UAVs we need. Tier 1 could be
a property to lower the requirements, but that can be done later.
This commit is contained in:
Ethan Lee
2025-08-22 14:32:28 -04:00
parent dee2414ee7
commit 0fcaf47658
2 changed files with 38 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
include/SDL3/SDL_gpu.h
View File

@@ -235,7 +235,8 @@
* SDL driver name: "direct3d12"
*
* Supported on Windows 10 or newer, Xbox One (GDK), and Xbox Series X|S
* (GDK). Requires a GPU that supports DirectX 12 Feature Level 11_1.
* (GDK). Requires a GPU that supports DirectX 12 Feature Level 11_0 and
* Resource Binding Tier 2 or above.
*
* ### Metal
*

39
src/gpu/d3d12/SDL_gpu_d3d12.c
View File

@@ -109,8 +109,8 @@
#define DXGI_GET_DEBUG_INTERFACE_FUNC "DXGIGetDebugInterface"
#define D3D12_GET_DEBUG_INTERFACE_FUNC "D3D12GetDebugInterface"
#define WINDOW_PROPERTY_DATA "SDL_GPUD3D12WindowPropertyData"
#define D3D_FEATURE_LEVEL_CHOICE D3D_FEATURE_LEVEL_11_1
#define D3D_FEATURE_LEVEL_CHOICE_STR "11_1"
#define D3D_FEATURE_LEVEL_CHOICE D3D_FEATURE_LEVEL_11_0
#define D3D_FEATURE_LEVEL_CHOICE_STR "11_0"
#define MAX_ROOT_SIGNATURE_PARAMETERS 64
#define D3D12_FENCE_UNSIGNALED_VALUE 0
#define D3D12_FENCE_SIGNAL_VALUE 1
@@ -8347,6 +8347,7 @@ static bool D3D12_PrepareDriver(SDL_VideoDevice *_this, SDL_PropertiesID props)
IDXGIFactory4 *factory4;
IDXGIFactory6 *factory6;
IDXGIAdapter1 *adapter;
bool supports_64UAVs = false;
// Early check to see if the app has _any_ D3D12 formats, if not we don't
// have to fuss with loading D3D in the first place.
@@ -8446,12 +8447,39 @@ static bool D3D12_PrepareDriver(SDL_VideoDevice *_this, SDL_PropertiesID props)
return false;
}
SDL_COMPILE_TIME_ASSERT(featurelevel, D3D_FEATURE_LEVEL_CHOICE < D3D_FEATURE_LEVEL_11_1);
// Check feature level 11_1 first, guarantees 64+ UAVs unlike 11_0 Tier1
res = D3D12CreateDeviceFunc(
(IUnknown *)adapter,
D3D_FEATURE_LEVEL_CHOICE,
D3D_FEATURE_LEVEL_11_1,
D3D_GUID(D3D_IID_ID3D12Device),
(void **)&device);
if (SUCCEEDED(res)) {
supports_64UAVs = true;
} else {
res = D3D12CreateDeviceFunc(
(IUnknown *)adapter,
D3D_FEATURE_LEVEL_CHOICE,
D3D_GUID(D3D_IID_ID3D12Device),
(void **)&device);
if (SUCCEEDED(res)) {
D3D12_FEATURE_DATA_D3D12_OPTIONS featureOptions;
SDL_zero(featureOptions);
res = ID3D12Device_CheckFeatureSupport(
device,
D3D12_FEATURE_D3D12_OPTIONS,
&featureOptions,
sizeof(featureOptions));
if (SUCCEEDED(res) && featureOptions.ResourceBindingTier >= D3D12_RESOURCE_BINDING_TIER_2) {
supports_64UAVs = true;
}
}
}
if (SUCCEEDED(res)) {
D3D12_FEATURE_DATA_SHADER_MODEL shaderModel;
shaderModel.HighestShaderModel = D3D_SHADER_MODEL_6_0;
@@ -8473,6 +8501,11 @@ static bool D3D12_PrepareDriver(SDL_VideoDevice *_this, SDL_PropertiesID props)
SDL_UnloadObject(d3d12Dll);
SDL_UnloadObject(dxgiDll);
if (!supports_64UAVs) {
SDL_LogWarn(SDL_LOG_CATEGORY_GPU, "D3D12: Tier 2 Resource binding is not supported");
return false;
}
if (!supports_dxil && !has_dxbc) {
SDL_LogWarn(SDL_LOG_CATEGORY_GPU, "D3D12: DXIL is not supported and DXBC is not being provided");
return false;