Texture Paint

Texture Paint blends up to three detail textures onto your terrain using a red / green / blue paint mask. Switch to Texture Paint mode from the top of the editor to open the brush, automasking tools, and channel texture pickers.

How Terrain Texturing Works

Main texture: The base look of the ground. After a satellite import this is the aerial image. For blank tracks it comes from styles like Grasslands or Desert, or from a custom terrain diffuse material you pick in Terrain Settings.
Paint mask: A red / green / blue map that says where each of the three detail textures shows up. Painting in Texture Paint edits this mask.
Color channels: Red, green, and blue are just three paint slots. By default they ship as sand, grass, and rock, but that is only a starting point. Assign any detail material you want to any channel, so blue does not have to be rock, red does not have to be sand, and so on.
Blending: Detail textures blend with the main texture. Dark spots in the main image still show through, so painted detail over a shady area stays darker too.
Physics: Texture paint is visual only. It does not change grip or surface physics. Terrain still drives like grass ground unless you add real surfaces or roads.

Custom Textures

Bring your own looks through the Asset Bank and assign them to any channel:

Open the Material Creator.
Create a material with type Terrain detail red channel, Terrain detail green channel, or Terrain detail blue channel, matching the paint slot you want to fill. Upload your diffuse texture and save it to your asset bank.
For a custom base ground look (instead of Grasslands / Desert / Satellite), create a Terrain diffuse material the same way, then pick it under Terrain Style in Terrain Settings.
Back in Texture Paint, use the three colored swatches to open each channel and choose your saved material, or reset that channel to Default.

Dirt, moss, gravel, snow, cracked earth, or anything else works. The channel color only controls where it paints, not what the texture has to look like.

You can also browse materials other people have shared in the Asset Bank. If your source images are not ready yet, the DDS converter tools help turn PNG or JPG files into textures Assetto Corsa can use.

Getting a Starting Mask

New tracks already get a soft noise-based mask so the ground is not a flat single color. From the Automasking panel you can rebuild that base:

Noise fill - Fill the mask with two channel colors and a noise pattern. Good when you are not using satellite imagery.
Color (Diffuse) - Sample colors from the terrain (or satellite image) with the eyedropper, set how wide each color matches, then click Apply Diffuse Automask.
Slope angle - Paint from steepness into the three channels (by default flatter toward the red slot, mid toward green, steeper toward blue). Click Apply Slope Automask.

After that, refine by hand with the texture brush.

Brush Settings

Pick a paint color (red, green, or blue), then adjust:

Brush Size - How wide the stroke is (also Ctrl + scroll)
Edge Confidence - How strongly the stroke writes into the mask
Brush Hardness - Soft edge versus hard edge

Left click + drag paints on the terrain. Clear mask wipes the painted mask so you can start over.

Detail Tiling

Under Detail Tiling you control how large each channel texture appears on the ground (meters per tile) for red, green, and blue, plus the shared normal map scale. Lower values make the texture repeat more often; higher values stretch it out.

View Modes

While Texture Paint is active, the top bar offers:

Mask View - Colored overlay of what you painted (red / green / blue)
Live View - The blended result as it will look
Mask opacity - How strong the mask overlay is in Mask View
Mask resolution - 1024 or 2048. Higher is sharper, and uses more memory

Automask Road

Use Automask road to paint a chosen channel color along your roads. Pick the swatch color first, then run the automask. Handy for putting a specific detail look (dirt, gravel, sand, and so on) along road edges.

Tips

Plan in Mask View, then check Live View before you call it done
Lower Edge Confidence for softer blends between channels
Use Color or Slope automask after a satellite import, then clean up by hand
Treat sand / grass / rock as the default starter set, then swap channel materials to whatever your track needs
Remember paint is visual only. Use Surfaces if you need different driving physics on the ground