DirectX Bindings

C3 bindings for Direct3D 12, DXGI, and D3D Compiler APIs.

Note

The DirectX bindings was created by hand and may require further review and testing.

Features
COM Interface Overview
- Interface Inheritance
Enumerations
Flags
Linking
Examples

Features

Include bindings as modules for d3d12, dxgi and d3dc (d3dcompiler).
D3D12, DXGI and D3D prefixes have been stripped from all types, functions and enum variants.
Type-safe wrappers for enumerations (using enum) and bit flags (using bitstruct).
Complete COM interface compatibility.

COM Interface Overview

COM interfaces in these bindings follow the standard COM vtable pattern. Each interface is represented as a struct containing a pointer to its vtable:

struct IUnknown
{
    IUnknownVTable* vtbl;
}

The vtable itself contains function pointers for all interface methods:

struct IUnknownVTable
{
    QueryInterfaceFn queryInterface;
    AddRefFn addRef;
    ReleaseFn release;
}

Interface functions are provided as inline wrapper methods that call through the vtable:

fn Win32_HRESULT IUnknown.queryInterface(
    &self,
    Win32_GUID* riid,
    void** ppvObject
) @inline =>
    self.vtbl.queryInterface(self, riid, ppvObject);

Interface Inheritance

COM interfaces inherit from each other by embedding the parent's vtable structure first. For example, all DirectX interfaces inherit from IUnknown, so their vtables begin with queryInterface, addRef, and release.

Consider IDebug which inherits from IUnknown:

struct IDebug
{
    IDebugVTable* vtbl;
}

struct IDebugVTable
{
    inline IUnknownVTable _base;  // Inherited methods first
    
    // IDebug-specific methods
    IDebug_EnableDebugLayerFn enableDebugLayer;
}

The inline IUnknownVTable _base; ensures that the first three function pointers in IDebugVTable are exactly the same as IUnknownVTable:

queryInterface
addRef
release

This means an IDebug* can be safely cast to IUnknown* because they share the same memory layout at the beginning.

Enumerations

Most enums are sequential, but when there are gaps in the original values, __UNUSED* entries are added to maintain proper indexing:

enum StateObjectType : int
{
    COLLECTION,
    __UNUSED0,
    __UNUSED1,
    RAYTRACING_PIPELINE,
    EXECUTABLE,
}

However, when the enum has large gaps that would be impractical to fill, constants are used instead:

typedef SamplerFeedbackTier = int;
const SamplerFeedbackTier SAMPLER_FEEDBACK_TIER_NOT_SUPPORTED = 0;
const SamplerFeedbackTier SAMPLER_FEEDBACK_TIER_0_9           = 90;
const SamplerFeedbackTier SAMPLER_FEEDBACK_TIER_1_0           = 100;

Flags

C3's bitstruct feature provides type-safe, efficient handling for all flags:

bitstruct UsageFlags : uint
{
    uint __unused0          : 0..3;
    bool shaderInput        : 4;
    bool renderTargetOutput : 5;
    bool backBuffer         : 6;
    bool shared             : 7;
    bool readOnly           : 8;
    bool discardOnPresent   : 9;
    bool unorderedAccess    : 10;
    uint __unused1          : 11..31;
}

Linking

To use these D3D12 bindings, the required libraries need to be avaiable:

Required Libraries

// In the manifest.json configuration
"linked-libraries": [
    "d3d12",           // System library - D3D12 core functionality  
    "dxgi",            // System library - DirectX Graphics Infrastructure
    "d3dcompiler_47",  // Provided library - Shader compilation
    "user32",          // System library - Windows user interface
    "gdi32"            // System library - Graphics Device Interface
]

Library Details

System Libraries (Windows SDK):

d3d12.lib - Core Direct3D 12 runtime, handles device creation, command lists, resources
dxgi.lib - DXGI interfaces for swap chains, adapters, and display management
user32.lib - Windows user interface functions, needed for window creation and message handling
gdi32.lib - Graphics Device Interface, provides basic graphics operations and device contexts

Provided Library:

d3dcompiler_47.lib - D3D shader compiler library, included with these bindings since it's not always present in the Windows SDK by default

Examples

For a complete working example, see the Hello Triangle sample.

Capati / directx.c3l