American Truck Simulator: Best config.cfg for High-Res Mirror Detail

The primary technical challenge is that each mirror renders the entire outside scene separately. To maintain performance while increasing resolution, we must balance the Mirror Scale with the Buffer Page Size to prevent engine hitching.

File Path & Setup

1. Navigate to: C:\Users\[YourName]\Documents\American Truck Simulator\config.cfg
2. Open with: Notepad or Notepad++.
3. Pro Tip: If you use Camera Mirrors (found in modern trucks like the Kenworth T680), these settings are even more critical as the digital screens require high pixel density to look realistic.

Optimized “Crystal View” Configuration Table

Parameter	Recommended Value	Technical Purpose
r_mirror_view_distance	600	The Horizon Fix. Extends mirror draw distance (Default Ultra is 200).
r_mirror_scale_x	2.0	Multiplier for horizontal mirror resolution.
r_mirror_scale_y	2.0	Multiplier for vertical mirror resolution.
r_deferred_mirrors	2	Enables advanced lighting passes for mirror reflections.
r_buffer_page_size	50	Increases memory headroom to handle high-res texture streaming.

// Enhanced Mirror & Rendering Configuration
uset r_mirror_view_distance "600"
uset r_mirror_scale_y "2.0"
uset r_mirror_scale_x "2.0"
uset r_deferred_mirrors "2"
uset r_buffer_page_size "50"
uset g_reflection_scale "3"
uset g_light_distance_factor "4"
uset r_sun_shadow_texture_size "4096"

HowTo: Engineering the Perfect Mirror Clarity

Follow these GameEngineer.net technical steps to achieve maximum visibility:

1. Scaling Beyond Ultra: In your config.cfg, the parameters r_mirror_scale_x and r_mirror_scale_y act as a multiplier for the mirror’s internal resolution. Setting these to 2.0 effectively doubles the pixel density ($Res_{total} \times 4$). If you have a high-end GPU (RTX 4080/5090), you can experiment with 4.0, though the diminishing returns are high.
2. Extended Draw Distance: The default “Ultra” mirror distance in the UI is capped at 200. By setting r_mirror_view_distance "600", you can see traffic and scenery much further back, which is essential for safely merging on high-speed interstates.
3. The “Pink Mirror” Fix: If your mirrors appear pink or flickery after these changes, it means the engine is running out of memory. Ensure r_buffer_page_size is set to at least 30 or 50. This provides the Prism3D engine the temporary VRAM “scratchpad” needed for the extra rendering passes.
4. Reflection Balance: Pair these mirror tweaks with g_reflection_scale "3". This ensures that the light reflecting off your truck’s chrome or polished paint matches the high-quality lighting you are now seeing in the mirrors.
5. Performance Check: Each mirror is a separate “camera.” If you use hood mirrors, main mirrors, and the F2 overlay, you are asking the game to render the world up to 9 times. If FPS drops, lower r_mirror_scale back to 1.0 but keep the view_distance high for better utility.

Technical Explanation: Mirror Render Scale ($S_{mir}$)

In American Truck Simulator, mirrors use a technique called Render-to-Texture. The engine captures the scene from a secondary camera position and “paints” it onto the mirror surface.

By modifying the r_mirror_scale parameters, you are increasing the resolution of that texture before it is applied to the mirror geometry. A scale of 2.0 ensures that the texture is sharp enough that you can read the license plates or identify the make of the car behind you ($C_{ident}$). When combined with r_deferred_mirrors "2", the engine applies the same high-quality lighting and shadow cascades used in the main view, creating a cohesive and realistic visual experience.