D3D12 Split/backend

src/igl/Buffer.h

@@ -80,6 +80,21 @@ struct BufferDesc {
   /** @brief Identifier used for debugging */
   std::string debugName;
 
+  /**
+   * @brief Element stride in bytes for storage buffers.
+   *
+   * For buffers created with BufferTypeBits::Storage, this describes the size of a single
+   * structured element when the buffer is viewed as a StructuredBuffer / RWStructuredBuffer.
+   *
+   * Backends that create structured SRV/UAV views (such as D3D12) use this value to populate
+   * D3D12_BUFFER_SRV / D3D12_BUFFER_UAV StructureByteStride and to compute NumElements.
+   *
+   * A value of 0 means "unknown/unspecified" and backends may fall back to a default
+   * element size (typically 4 bytes) for compatibility with existing code that assumes
+   * float / uint elements.
+   */
+  size_t storageStride = 0;
+
   BufferDesc(BufferType type = 0,
              const void* IGL_NULLABLE data = nullptr,
              size_t length = 0,

src/igl/Common.h

@@ -28,7 +28,14 @@ using Deleter = void (*)(void* IGL_NULLABLE);
 
 /// Device Capabilities or Metal Features
 constexpr uint32_t IGL_TEXTURE_SAMPLERS_MAX = 16;
-constexpr uint32_t IGL_VERTEX_ATTRIBUTES_MAX = 24;
+
+// Maximum vertex attributes across all backends
+// - D3D12: D3D12_IA_VERTEX_INPUT_RESOURCE_SLOT_COUNT = 32
+// - Vulkan: VkPhysicalDeviceLimits::maxVertexInputAttributes (typically >= 16, commonly 32)
+// - Metal: 31 (Metal Feature Set Tables)
+// - OpenGL: GL_MAX_VERTEX_ATTRIBS (typically >= 16)
+// Setting to 32 ensures compatibility with D3D12 (the most widely-supported modern API)
+constexpr uint32_t IGL_VERTEX_ATTRIBUTES_MAX = 32;
 
 // maximum number of buffers that can be bound to a shader stage
 // See maximum number of entries in the buffer argument table, per graphics or kernel function
@@ -136,6 +143,7 @@ enum class BackendType {
   OpenGL,
   Metal,
   Vulkan,
+  D3D12,
   // @fb-only
   Custom,
 };
@@ -146,6 +154,7 @@ enum class BackendFlavor : uint8_t {
   OpenGL_ES,
   Metal,
   Vulkan,
+  D3D12,
   // @fb-only
 };
 

src/igl/Device.cpp

@@ -50,6 +50,8 @@ Color IDevice::backendDebugColor() const noexcept {
     return {1.f, 0.f, 1.f, 1.f};
   case BackendType::Vulkan:
     return {0.f, 1.f, 1.f, 1.f};
+  case BackendType::D3D12:
+    return {0.f, 1.f, 1.f, 1.f};  // Match Vulkan for parity testing
   // @fb-only
     // @fb-only
   case BackendType::Custom:

src/igl/DeviceFeatures.h

@@ -154,18 +154,30 @@ enum class DeviceRequirement {
  * @brief DeviceFeatureLimits provides specific limitations on certain features supported on the
  * device
  *
- * BufferAlignment              Required byte alignment for buffer data
- * BufferNoCopyAlignment        Required byte alignment for no copy buffer data
- * MaxBindBytesBytes            Maximum number of bytes that can be bound with bindBytes
- * MaxCubeMapDimension          Maximum cube map dimensions
- * MaxFragmentUniformVectors    Maximum fragment uniform vectors
- * MaxMultisampleCount          Maximum number of samples
- * MaxPushConstantBytes         Maximum number of bytes for Push Constants
- * MaxTextureDimension1D2D      Maximum texture dimensions
- * MaxUniformBufferBytes        Maximum number of bytes for a uniform buffer
- * MaxStorageBufferBytes        Maximum number of bytes for storage buffers
- * MaxVertexUniformVectors      Maximum vertex uniform vectors
- * PushConstantsAlignment       Required byte alignment for push constants data
+ * BufferAlignment                      Required byte alignment for buffer data
+ * BufferNoCopyAlignment                Required byte alignment for no copy buffer data
+ * MaxBindBytesBytes                    Maximum number of bytes that can be bound with bindBytes
+ * MaxCubeMapDimension                  Maximum cube map dimensions
+ * MaxFragmentUniformVectors            Maximum fragment uniform vectors
+ * MaxMultisampleCount                  Maximum number of samples
+ * MaxPushConstantBytes                 Maximum number of bytes for Push Constants
+ * MaxTextureDimension1D2D              Maximum texture dimensions for 1D and 2D textures
+ * MaxTextureDimension3D                Maximum texture dimensions for 3D textures
+ * MaxStorageBufferBytes                Maximum number of bytes for storage buffers
+ * MaxUniformBufferBytes                Maximum number of bytes for a uniform buffer
+ * MaxVertexUniformVectors              Maximum vertex uniform vectors
+ * PushConstantsAlignment               Required byte alignment for push constants data
+ * ShaderStorageBufferOffsetAlignment   Required byte alignment for shader storage buffer offset
+ * MaxComputeWorkGroupSizeX             Maximum compute work group size in X dimension
+ * MaxComputeWorkGroupSizeY             Maximum compute work group size in Y dimension
+ * MaxComputeWorkGroupSizeZ             Maximum compute work group size in Z dimension
+ * MaxComputeWorkGroupInvocations       Maximum total compute work group invocations
+ * MaxVertexInputAttributes             Maximum number of vertex input attributes
+ * MaxColorAttachments                  Maximum number of color attachments (render targets)
+ * MaxDescriptorHeapCbvSrvUav           Maximum CBV/SRV/UAV descriptors in shader-visible heap (I-005)
+ * MaxDescriptorHeapSamplers            Maximum sampler descriptors in shader-visible heap (I-005)
+ * MaxDescriptorHeapRtvs                Maximum RTV descriptors in CPU-visible heap (I-005)
+ * MaxDescriptorHeapDsvs                Maximum DSV descriptors in CPU-visible heap (I-005)
  */
 enum class DeviceFeatureLimits {
   BufferAlignment = 0,
@@ -176,11 +188,23 @@ enum class DeviceFeatureLimits {
   MaxMultisampleCount,
   MaxPushConstantBytes,
   MaxTextureDimension1D2D,
+  MaxTextureDimension3D,
   MaxStorageBufferBytes,
   MaxUniformBufferBytes,
   MaxVertexUniformVectors,
   PushConstantsAlignment,
   ShaderStorageBufferOffsetAlignment,
+  MaxComputeWorkGroupSizeX,
+  MaxComputeWorkGroupSizeY,
+  MaxComputeWorkGroupSizeZ,
+  MaxComputeWorkGroupInvocations,
+  MaxVertexInputAttributes,
+  MaxColorAttachments,
+  // I-005: Descriptor heap size limits for cross-platform compatibility
+  MaxDescriptorHeapCbvSrvUav,
+  MaxDescriptorHeapSamplers,
+  MaxDescriptorHeapRtvs,
+  MaxDescriptorHeapDsvs,
 };
 
 /**
@@ -192,7 +216,7 @@ enum class DeviceFeatureLimits {
  * Metal         Metal API (macOS, iOS, etc.)
  * SpirV         Standard Portable Intermediate Representation open standard format
  */
-enum class ShaderFamily : uint8_t { Unknown, Glsl, GlslEs, Metal, SpirV };
+enum class ShaderFamily : uint8_t { Unknown, Glsl, GlslEs, Metal, SpirV, Hlsl };
 
 /**
  * @brief ShaderVersion provides information on the shader family type and version

src/igl/PlatformDevice.h

@@ -27,6 +27,7 @@ enum class PlatformDeviceType {
   OpenGLMacOS,
   OpenGLWebGL,
   Vulkan,
+  D3D12,
   // @fb-only
 };