Unreal Engine X - Getting Started
Unreal Engine X is a focused Unreal Engine 5 fork built around a deliberately constrained desktop rendering configuration.
Rather than attempting to preserve every platform, rendering backend, compatibility mode, and high-level UE5 feature simultaneously, the fork deliberately narrows the configuration around the modern systems.
The primary renderer remains Direct3D 12 / Shader Model 6 / Deferred.VulkanRHI is being modernized around a Vulkan 1.3 desktop baseline and functionality backported from newer Unreal Engine development.
The primary target is:
- Windows 64-bit
- Direct3D 12
- Shader Model 6
- Deferred Lighting
A modernized Vulkan 1.3 / SM6 / Full Bindless path is also being worked on as the alternative desktop RHI.
Overview
Modern Unreal Engine releases provide a broad collection of rendering systems, platform abstractions, compatibility paths, and high-level features. Unreal Engine X intentionally narrows that configuration to provide a smaller and more predictable foundation for projects that do not require the complete default Epic feature stack.
Key Features
- Controlled engine foundation — non-essential systems and rendering paths can be disabled or bypassed instead of remaining implicitly active.
- Opt-in feature design — features are restored when required instead of assuming the complete UE5 feature stack.
- Windows / D3D12 / SM6 target — development is focused on a modern Windows desktop rendering configuration.
- Deferred-first renderer — full project-wide Forward Shading is disabled while selected forward infrastructure remains available for future specialized passes.
- D3D12 and bindless improvements — descriptor management, residency handling, heap behavior, and state-cache paths include additional controls and optimizations.
- Full Bindless SM6 configuration — both D3D12 SM6 and Vulkan SM6 are intended to use Unreal's full-resource bindless configuration.
- Modernized VulkanRHI — the Windows Vulkan path is being moved from older Vulkan 1.1-era assumptions toward a Vulkan 1.3 baseline.
- RDG improvements — includes an optional lightweight cache for repeated live-pass traversal.
- Alternative LOD dithering — dithered LOD transitions can use ordered Bayer patterns instead of the default Epic pseudo-random screen-space pattern.
- AMD FidelityFX SPD integration — selected post-processing downsample chains can generate their mips through a single compute dispatch.
- Alternative FidelityFX GPU radix sorting — provides an additional radix backend using FidelityFX GPU sorting.
- meshoptimizer integration — meshoptimizer is available as an alternative LOD reduction path.
- Clustered Deferred restored — the deprecated Clustered Deferred path has been restored and is being developed further.
- Cascaded shadow improvements — UE6 shadow-depth reuse backport, static caster LOD and caster significance culling. See Features.
- GT7 tonemapper — selectable next to Filmic and ACES through UE 5.8's LUT tonemapping method. See Features.
- Spectral rendering (experimental) — deferred lights carry real emission spectra. See Spectral Rendering.
- Visibility buffer (experimental) — hybrid visibility buffer for foliage. See Visibility Buffer.
- Hardware tessellation — hull/domain shader displacement for static meshes and landscape on D3D12. See Features.
- Directional shadow filters — PCSS+, PCSS Cone and DPCF (Call of Duty: Black Ops Cold War). See Features.
- UE5 + RE:Dox — Unreal Insights traces exported as compact, LLM-ready summaries. See UE5 + RE:Dox.
Integrated Engine Submodules / Plugins
Several external projects are integrated into the engine repository as submodules or engine plugins:
- AntiLag2 — AMD Radeon Anti-Lag 2 integration for reducing end-to-end latency on AMD GPUs.
- Box3DUnreal — a lightweight Unreal Engine integration of Box3D, providing an alternative physics environment for experimentation and specialized gameplay systems.
- TBImGui — a Dear ImGui integration for Unreal Engine supporting runtime and editor tooling, PIE, packaged builds, multi-viewport UI, and remote debugging workflows.
- UE5Coro — deeply integrated C++20 coroutine support for Unreal Engine, including latent operations, asynchronous engine tasks, gameplay-oriented awaiters, and coroutine-based control flow.
Documentation
| Page | Contents |
|---|---|
| Setup | Engine setup, dependencies, cleanup and disk footprint |
| Features | RHI/RDG, rendering, shadows, sky, tonemapping and third-party changes |
| Visibility Buffer | Experimental hybrid visibility buffer: pipeline, traces, bottlenecks |
| Spectral Rendering | Experimental spectral direct lighting |
| UE5 + RE:Dox | Insights trace export and LLM summaries through RE:Dox |
| Flow Volumes | Flow setup, GPU selection, quality controls and demo-map availability |
| Backports and Engine Fixes | Grouped backport/fix inventory and integration status |
| UI and XDash | Partial ImGui editor presentation and quality-of-life dashboard controls |
| References | Papers, talks and code the changes are based on |