ETS2 parallax interiors: how the rendering trick works

Parallax interiors are a shader-based way to give buildings visible rooms behind their windows without modelling every room as full geometry. SCS Software described the technique on 15 February 2025 after using it in Euro Truck Simulator 2, American Truck Simulator, the Greece DLC and the Return to Winterland event.

The illusion behind the windows

The system treats many interiors as open boxes defined by position, dimensions and textures. A shader projects the room surfaces so they appear to have depth when the camera moves past a building. The scene is not a complete three-dimensional apartment or shop, so the team has to control viewing angles and other limits that can expose distortions.

SCS said this approach can draw many interior instances from compact, parameterized geometry and modest texture resources. The same rendering process can simulate lighting for different times of day and account for glass, curtains and other window coverings.

How artists build the rooms

The production workflow combines shaders, texture atlases and an Interior Window Tool integrated with the studio’s Maya-based asset pipeline. Artists assign room types to groups of window faces, while the tool checks orientation, proximity and whether windows belong on the same floor. A randomization option helps distribute rooms across large building surfaces.

The team researched broad categories that could work across many countries and cities: offices and administrative spaces, apartments, restaurants and shops. Each atlas also needed variations in size, price level, lighting, blinds, shutters and decorations. That balance lets the same system cover many buildings without making every window look identical.

Why SCS built the feature

The goal was to improve the depth of dense streets while keeping asset creation and rendering manageable. A full model behind every window would demand far more geometry, authoring time and draw calls. Parallax mapping concentrates that work in reusable shaders, tools and atlases.

In the February 2025 article, SCS said it planned to add more interiors, update some older assets and extend the technique to open spaces such as garages. Those points were a development roadmap, not a guarantee that every existing building had already been converted.

Sources

• Steam: Under the Hood — Parallax Interiors
• SCS Software: official technical interview