Real-time 3D graphics have come a long way over the past decade, but there’s one technology that’s rapidly redefining the limits of visual fidelity in games and simulations: ray tracing in Unity. This groundbreaking feature, once reserved for pre-rendered Hollywood scenes or architectural visualizations, is now fully accessible to game developers working in Unity’s High Definition Render Pipeline (HDRP).
Ray tracing allows developers to simulate the physical behavior of light with astonishing precision, opening the door to immersive lighting, lifelike shadows, and reflections that respond dynamically to the environment.
But ray tracing is more than just a visual gimmick: it changes how lighting is conceptualized and implemented, shifting the developer’s mindset from faking realism to embracing it natively through the rendering engine. For creators like you and I aiming to push the envelope, whether in hyperrealistic simulations or richly stylized experiences, understanding how ray tracing works and how to use it efficiently can be a game-changer.
In this article, you will embark on a practical journey through the setup, strengths, limitations, and performance considerations of ray tracing in Unity.
You may also like: These are the 5 best games to test ray tracing on!
What is ray tracing in Unity?
Unity’s real‑time ray tracing uses the High Definition Render Pipeline (HDRP) with the DirectX 12 DXR API to simulate reflections, shadows, global illumination, and subsurface scattering in a way that rasterization cannot.
It traces rays from the camera into the scene to compute lighting interactions that often use off‑screen information. Unity partnered with NVIDIA and demonstrated this with a realistic BMW 8 Series rendered in real time that was nearly indistinguishable from a filmed car.
These effects include ray‑traced ambient occlusion shadows that are more precise than screen space techniques, reflections that include objects not visible on screen, and global illumination that reacts dynamically to lighting changes.
This brings photorealistic fidelity to architectural visualizations, engineering scenes or atmospheric game levels.
Using ray tracing in a Unity project
Ray tracing requires a project configured with HDRP and running on DirectX 12 on Windows. HDRP introduced support beginning with Unity 2019.3 and continues into recent versions.
Hardware and API Requirements
Unity’s documentation lists supported GPUs, including NVIDIA GeForce RTX 20 and 30 series and AMD RX 6000 series. Some older GTX models also work via fallback.
The system must support DirectX 12 and run at least Windows 10 version 1809. Drivers must be up-to-date. Unity offers the function SystemInfo.supportsRayTracing to verify support at runtime.
Project Setup
Developers must create or upgrade to an HDRP asset, and then switch the rendering API from DirectX 11 to DirectX 12. This can be done using the HDRP Wizard under Window → Rendering → HDRP Wizard or manually in Project Settings.
Then static batching must be disabled because HDRP ray tracing cannot work with it enabled.
Enabling ray tracing features in the HDRP asset is the next step. The developer must check Realtime Ray Tracing in the rendering section of the asset inspector. After recompilation ray‑traced effects become available.
Final Steps in Scene
The developer validates build and frame settings, so cameras actually compute ray‑traced effects. Building must target 64‑bit (x86_64), ray tracing must be enabled per camera via frame settings, and scene content must be validated using the menu command Check Scene Content for Ray Tracing.
Effects and Visual Enhancements
Unity HDRP replaces traditional screen space lighting techniques with ray‑based alternatives.
- Ray‑Traced Ambient Occlusion provides realistic contact shadows.
- Ray‑Traced Global Illumination simulates bounced and indirect light instead of relying on static lightmaps.
- Ray‑Traced Reflections show mirror‑like reflections including off‑screen geometry.
- Ray‑Traced Shadows improve shadow crispness and accuracy for directional lights.
- Recursive ray tracing enables refractive and reflective materials to self‑interact.
- Ray‑Traced Subsurface Scattering gives more realistic rendering of translucent materials.
When chosen in project or effect settings, “Performance” mode optimizes for real‑time speed, while “Quality” mode aims for technical demos or high‑end fidelity. Asset settings allow per-effect selection if “Both” mode is picked.
Limitations and caveats
Despite its realism, ray tracing in Unity HDRP has limitations. It only works in DX12 environments and does not support vertex-animated meshes, emissive decals, tessellation or MSAA. So path tracing and certain shader graph nodes such as NormalFromHeight and DDX/DDY are not compatible.
Reflection probes do not support ray‑traced content and orthographic cameras may show artifacts. Volumetric fog, VFX, water, and Graphics.DrawMesh calls are unsupported under ray tracing. Meshes that mix materials may behave unpredictably in acceleration structures.
Ray tracing can also be resource-intensive. Use of the performance mode and tuning of ray‑traced effect presets is essential. Developers should consider denoising approaches such as NVIDIA RTXGI integration or temporal accumulation to enhance frame rate.
Testing on target hardware is critical. Visual fidelity must be balanced with frame rates for gameplay. LOD systems adapted to ray tracing can help drop resolution or reduce bounces at runtime to maintain responsiveness.
Why it matters for game production
Ray tracing in Unity signals a shift from baked or screen‑space lighting methods to physically accurate real‑time rendering. It supports dynamic scenes, moving objects, and changing lighting while maintaining high visual fidelity.
Game developers can deliver experiences that feel more immersive with realistic reflections, natural shadows, and consistent indirect lighting. Unity’s HDRP pipeline makes it accessible where hardware allows, and the trade‑offs are well understood.
Through this detailed look at ray tracing, hopefully, now you understand how to set up Unity HDRP for DXR, which visual effects are enabled, what limitations to expect and how performance can be managed. Ray tracing lifts graphics closer to cinema quality, but only if developers balance hardware demands and design clarity.
For studios or teams looking to explore real‑time ray tracing use cases or push visuals further, we here at Main Leaf specialize in delivering rich Unity projects with advanced rendering techniques. With years of experience in game development using Unity and Unreal, we help developers bring their vision to life with cutting‑edge graphics and optimization workflows.
If exploring ray tracing in Unity for your next project appeals, get in contact with us to have a conversation about how to implement it effectively!
