MFS Engine Rendering Backends

This document provides an overview of the various graphics backends supported by the MFS Engine.

Supported Backends

MFS Engine supports multiple rendering backends to ensure cross-platform compatibility and leverage platform-specific optimizations: | Backend | Platforms | Features | Status | |---------|-----------|----------|--------| | Vulkan | Windows, Linux, Android | High performance, low overhead | Complete | | DirectX 12 | Windows 10+ | Modern GPU features, raytracing | Complete | | DirectX 11 | Windows 7+ | Wide compatibility | Complete | | Metal | macOS, iOS | Native Apple performance | Beta | | OpenGL | Windows, Linux, macOS | Cross-platform compatibility | Complete | | OpenGL ES | Android, iOS | Mobile support | Beta | | WebGPU | Web browsers | Modern web standard | Alpha | | Software | All platforms | Fallback renderer | Basic |

Backend Selection

The engine will automatically choose the most performant backend available on the current platform. You can also explicitly select a backend:

// Using the Config struct
var config = mfs.Config{
    .renderer_backend = .vulkan,
    // other configuration...
};

// Or at runtime
app.setGraphicsBackend(.dx12) catch |err| {
    // Handle error if backend is not available
};

Backend-Specific Features

Vulkan

The Vulkan backend provides:

Compute shader support
Advanced memory management
Multi-threaded command buffer recording
Full validation layer integration
Explicit synchronization control

File location: src/graphics/backends/vulkan_backend.zig

DirectX 12

The DirectX 12 backend provides:

DirectX Raytracing (DXR) integration
DirectStorage API support
Variable Rate Shading (VRS)
Mesh shaders
DirectML for hardware accelerated machine learning

File location: src/graphics/backends/d3d12_backend.zig

DirectX 11

The DirectX 11 backend provides:

Wide compatibility with Windows systems
Feature level targeting
Legacy hardware support
Mature tooling integration

File location: src/graphics/backends/d3d11_backend.zig

Metal

The Metal backend provides:

Native performance on Apple platforms
Metal shader language compilation
Metal Performance Shaders integration
Dynamic resource management

File location: src/graphics/backends/metal_backend.zig

OpenGL

The OpenGL backend provides:

Maximum cross-platform compatibility
Legacy hardware support
Simpler API for learning and debugging

File location: src/graphics/backends/opengl_backend.zig

WebGPU

The WebGPU backend provides:

Modern web standard support
Cross-browser compatibility
Web worker integration

File location: src/graphics/backends/webgpu_backend.zig

Shader System

MFS uses a unified shader system that compiles to each backend's native format: 1. Write shaders in a high-level shader language (HLSL/GLSL-like syntax) 2. The engine shader compiler converts to backend-specific formats 3. Shader reflection generates appropriate bindings for each backend 4. Hot reloading is supported across all backends Example shader definition:

const standard_shader = mfs.shader.define(.{
    .vertex = @embedFile("shaders/standard.vert"),
    .fragment = @embedFile("shaders/standard.frag"),
    .reflection = true, // Enable automatic binding reflection
});

Feature Compatibility

The following table shows feature support across backends: | Feature | Vulkan | DX12 | DX11 | Metal | OpenGL | WebGPU | |---------|--------|------|------|-------|--------|--------| | Compute | ✅ | ✅ | ✅ | ✅ | ✅* | ✅ | | Raytracing | ✅ | ✅ | ❌ | ✅* | ❌ | ❌ | | Mesh Shaders | ✅ | ✅ | ❌ | ❌ | ❌ | ❌ | | VRS | ✅ | ✅ | ❌ | ✅ | ❌ | ❌ | | Bindless | ✅ | ✅ | ✅ | ✅ | ✅ | ❌ | | Async Compute | ✅ | ✅ | ❌ | ✅ | ❌ | ❌ | | HDR Output | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ | | GPU Timeline | ✅ | ✅ | ❌ | ✅ | ❌ | ✅ | \* Limited support or extension dependent

Backend Implementation Details

Each backend implements the core GraphicsDevice interface:

pub const GraphicsDevice = struct {
    // Interface functions implemented by each backend
    initFn: fn (allocator: std.mem.Allocator, options: Options) !*GraphicsDevice,
    deinitFn: fn (self: *GraphicsDevice) void,
    beginFrameFn: fn (self: *GraphicsDevice) !void,
    endFrameFn: fn (self: *GraphicsDevice) !void,
    createBufferFn: fn (self: *GraphicsDevice, desc: BufferDesc) !ResourceHandle,
    createTextureFn: fn (self: *GraphicsDevice, desc: TextureDesc) !ResourceHandle,
    // ... and many more functions
};

Adding Custom Backends

The engine supports adding custom rendering backends by implementing the GraphicsDevice interface: 1. Create a new file in src/graphics/backends/my_backend.zig 2. Implement the required interface functions 3. Register your backend with the engine See src/graphics/backends/template_backend.zig for a starting point.

Debugging and Profiling

Each backend includes specialized debugging and profiling capabilities:

Vulkan: Debug markers, validation layers, RenderDoc integration
DirectX: PIX integration, debug layers, GPU-based validation
Metal: Frame capture, shader debugging, Metal System Trace
OpenGL: KHR_debug extension, ARB_debug_output

Use the common API for cross-backend debugging:

renderer.beginDebugGroup("Shadow pass");
defer renderer.endDebugGroup();
// Rendering operations here

Performance Considerations

Different backends have different performance characteristics:

Vulkan/DX12: Require more explicit management but offer highest performance
Metal: Best performance on Apple platforms
DX11: Good balance of simplicity and performance on Windows
OpenGL: Simpler API with potentially higher driver overhead
WebGPU: Performance constrained by browser environment

Limitations and Known Issues

Feature Availability: Not all features are available on all backends
Extension Support: Some features rely on optional extensions
API Differences: Subtle differences in behavior may exist between backends
WebGPU: Still evolving, more limited than native backends

Testing Backend Compatibility

Use the built-in testing system to verify your code works across backends:

# Test all backends
zig build test

# Test specific backends
zig build test-vulkan
zig build test-d3d12
zig build test-opengl