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Rendering

Lucky Engine draws a scene in one of two render modes. Rasterized favours speed and keeps the editor responsive while you build and simulate. Path Traced calculates lighting, shadows, reflections and refraction by tracing rays through the scene geometry, for physically based images, videos and datasets.

Each Scene tab has its own render mode, so two tabs can show the same scene in different modes. Most other render settings, such as the denoiser, path-tracing sampling or ambient occlusion strength, belong to the project: they apply to every Scene tab and are saved with the project.

In short

Pick the render mode with the Rasterized and Path Traced buttons near the right end of a Scene tab's toolbar, or from View → Scene Renderer on the Rendering page. Path Traced needs a GPU with hardware ray tracing on Windows or Linux; on other machines the scene renders Rasterized. A Scene tab starts in the scene's default render mode, Path Traced for new scenes, and the project's denoiser starts as NVIDIA DLSS Ray Reconstruction.

In this section

  • Path Tracing

    Denoisers and DLSS modes, progressive refinement and sampling, view modes, the environment multiplier and the path tracing statistics.

  • Scene Renderer Panel

    Field-by-field reference of every page in the Scene Renderer panel, with defaults and ranges, and the matching C# API.

  • Cameras and Exposure

    Exposure modes, the viewport camera settings, and physical cameras with lens models, aperture depth of field and vignetting.

  • Lights and Materials

    How each light type, area lights, emissive materials and glass behave in each render mode.

The two render modes

Mode Best for How it renders
Rasterized Building scenes, running simulations, large scenes, fast feedback Real-time lighting with shadow maps, screen-space ambient occlusion and optional screen-space reflections.
Path Traced Final images, videos and training data that need physically based light Light, shadows, reflections, refraction and bounced light are calculated from the scene geometry with rays. A denoiser or progressive refinement removes the noise.

Both modes use the same scene, materials, lights and cameras, so you can switch at any time without changing the content.

Requirements

Feature Requirement
Rasterized Any supported system.
Path Traced Windows or Linux, with a GPU and graphics driver that support hardware ray tracing: NVIDIA RTX, AMD Radeon RX 6000 series or newer, or Intel Arc.
ReBLUR and ReLAX denoisers Any GPU that can run Path Traced.
NVIDIA DLSS Ray Reconstruction (Path Traced) and the NVIDIA DLSS upscaler (Rasterized) Windows or Linux, with an NVIDIA RTX GPU that supports DLSS.

macOS

The macOS build is experimental and has no path tracing or DLSS. Scenes always render Rasterized there, the Path Traced button stays greyed out, and the Scene Renderer has no Upscaling section.

Switching render mode

  1. In the Scene tab's toolbar, find the two joined render-mode buttons near the right end: Rasterized and Path Traced. Hover over a button to see its name. The highlighted button is the mode in use.
  2. Click the mode you want.

You can also open View → Scene Renderer, select the Rendering page and set Render mode. The panel changes the active Scene tab, the one you clicked into most recently.

The render mode belongs to the Scene tab: other Scene tabs keep their own. You can switch it at any time, including during Play. The arrow joined to the right of the two buttons opens the Path Tracing menu, with the view mode and the denoiser; see Path Tracing.

Unsupported hardware and fallbacks

When a machine cannot run what a Scene tab or the project asks for, the editor falls back without changing the setting, so it works as chosen again on a machine that supports it.

  • No hardware ray tracing. The Path Traced button is greyed out, and its tooltip says that it needs ray-tracing hardware. A Scene tab set to Path Traced, for example one that starts on a new scene, renders Rasterized, and the toolbar highlights Rasterized. If the Scene Renderer's Render mode still reads Path Traced, choose Rasterized there or click Rasterized in the toolbar to see the Rasterized settings.
  • No DLSS. NVIDIA DLSS Ray Reconstruction is greyed out, with a tooltip saying that it requires an NVIDIA RTX GPU. While the project's denoiser is NVIDIA DLSS Ray Reconstruction, the viewport is denoised with ReBLUR instead. The NVIDIA DLSS upscaler of the Rasterized mode is greyed out too.

The toolbar's render-mode buttons, the Denoiser button in its Path Tracing menu and the Scene Renderer's Denoiser field always show what is actually in use, after any fallback.

Defaults for new and older scenes

A scene stores a default render mode. A Scene tab with nothing remembered yet, such as the Scene tab of a project you open for the first time, takes the default of each scene it opens. From the next time you open the project, the tab has remembered settings and keeps its own render mode, whichever scene it shows.

Scene Default render mode
Created in this version (File → New Scene, or the start scene of a New Project) Path Traced
Saved by 2026.2 or earlier Rasterized
The bundled Welcome scene Path Traced

Projects from the Unitree G1 and Emika Panda templates start from a scene downloaded with the template, so they use whatever default that scene has.

To change a scene's default, switch a Scene tab to the mode you want, open the toolbar's Camera menu and click Set Scene Default View, then save the scene. This also stores the tab's camera position and its overlay and collider settings; see What each Scene tab remembers.

The denoiser is not part of the scene. Every project, including one from an earlier version, starts with NVIDIA DLSS Ray Reconstruction in its Quality mode. The fallbacks above still apply: without ray tracing a Scene tab renders Rasterized, and without DLSS the viewport uses ReBLUR.

Upgrading from 2026.2

Scenes from earlier versions have no default render mode stored, so they open Rasterized in a Scene tab with nothing remembered. Click Path Traced to switch the tab. To make Path Traced the scene's default for everyone, also click Set Scene Default View and save the scene. Cameras in older scenes also open with automatic exposure, which can change how bright a scene looks; see Cameras and Exposure.

What works in each mode

Feature Rasterized Path Traced
Shadows Shadow maps, tuned on the Scene Renderer Shadows page Calculated from scene geometry and lights
Soft shadows Soft Shadows on point and spot lights, plus the Shadows page From area lights and emissive materials; directional, point and spot lights cast sharp shadows
Area lights Light the scene without casting shadows Light the scene with soft shadows
Emissive materials Appear bright, but do not light other objects Act as light sources
Ambient occlusion Scene Renderer Ambient Occlusion page Calculated from scene geometry; no setting
Reflections Screen-space: only objects visible on screen, off by default Calculated from scene geometry
Bounced (indirect) light Not simulated; the environment provides ambient light Simulated, up to Indirect bounces
Camera lens models, aperture depth of field, vignetting Not used; cameras render as a plain pinhole Yes
Post-process depth of field Yes Yes
Bloom Yes Yes, in the Lit view
Exposure modes Yes Yes
SMAA anti-aliasing Yes, except while the NVIDIA DLSS upscaler is active Yes
DLSS NVIDIA DLSS upscaling NVIDIA DLSS Ray Reconstruction denoising and upscaling
Point and spot lights Up to 1024 point lights and 1024 spot lights The 1024 limit does not apply
Camera far clip plane Applies Ignored

With more than 1024 point or 1024 spot lights, the Rasterized viewport stays usable, but rasterized recordings reject the frames rather than write them with lights missing.

For per-light details, see Lights and Materials. For lens, aperture and exposure, see Cameras and Exposure.

Where settings are saved

Render settings are kept in three places. A few are not saved at all.

Kept Settings
With the project, for every Scene tab and everyone who opens the project Denoiser, DLSS Mode and Temporal anti-aliasing; all Sampling settings and the Environment multiplier; the Rasterized Upscaler and its DLSS Mode; Main-view culling and Cascade shadow culling; every setting on the Ambient Occlusion, Reflections, Depth of Field and Anti-Aliasing pages except Occlusion only; the Bloom type and its convolution settings; Manual cascade splits
With each Scene tab, for you only Render mode and View mode; Occlusion only; the settings in the toolbar's Camera menu, separately for each scene the tab shows
With the scene Bloom Enabled, Intensity, Threshold, Threshold softness and Lens dirt intensity; Cascade split distribution, Near-plane offset (m), Far-plane offset (m) and Anchor cascades to origin; the scene's default view, stored with Set Scene Default View
Not saved The other Shadows settings; Show Light Complexity and Show Shadow Cascades; the lens dirt texture; the viewport camera's Speed and its Manual exposure value

The project's settings are saved a moment after each change, in EditorViewportSettings.yaml in the project folder. Keep that file under version control to share them with your team. They apply to the Scene tabs only: recordings have their own settings, described below.

Each Scene tab's settings are saved in your own file for the project, <ProjectName>.hproj.user, and come back the next time you open the project. They are not stored in the scene or shared with your team. See What each Scene tab remembers.

Settings stored in the scene are saved when you save the scene. Camera components, lights and materials are part of the scene too, so their settings, including a camera's exposure, are saved with it.

Rendering for recordings and gRPC

The viewport's render mode and sampling settings do not affect recordings. Each camera binding in Settings → Scene → Recorder, on the Video tab, has its own Render Mode, with its own denoiser and quality settings when set to Path Traced. Recordings can also use OIDN, a CPU denoiser that the viewport does not offer. See Recording and Video Encoding and FFmpeg.

Camera frames requested over gRPC follow the same binding: a camera whose binding is set to Path Traced returns path-traced colour frames. See gRPC API.

Troubleshooting

Path Traced is greyed out.
The GPU or its driver has no hardware ray tracing, or you are on macOS. Check the requirements and update the graphics driver. The scene renders Rasterized in the meantime.
NVIDIA DLSS Ray Reconstruction is greyed out.
DLSS needs an NVIDIA RTX GPU with DLSS support. Use ReBLUR or ReLAX instead.
The Log shows "NVIDIA DLSS failed to load".
DLSS could not start, so the viewport renders without it. Update the NVIDIA graphics driver, or choose another denoiser or set the Rasterized Upscaler to Off.
Two Scene tabs render the same scene differently.
The render mode and view mode belong to each Scene tab. Switch the other tab as well.
The path-traced image is noisy.
Choose a denoiser, or set the denoiser to None and keep the camera still so that progressive refinement can combine frames. See Path Tracing.
Moving objects leave trails.
ReBLUR and ReLAX reuse earlier frames and can ghost during motion. Compare the two, try NVIDIA DLSS Ray Reconstruction on an RTX GPU, or use None for still images.
Objects appear a moment after the scene opens in Path Traced mode.
Geometry is still being prepared. Objects appear as they become ready; the Statistics page shows how much is still pending.
A scene from 2026.2 looks brighter or darker.
Cameras now default to automatic exposure, and point and spot lights use physically based falloff. See Cameras and Exposure and Lights and Materials.
Distant directional shadows disappear in Rasterized mode.
Shadows fade out beyond Directional shadow distance (m) on the Scene Renderer Shadows page. Increase it.

Where to go next