The Problem
To make a believable countryside road environment, the road has to interact with the shape of the terrain, cutting through it rather than sitting on top of it. Adding a road to sculpted or procedural terrain this way requires modifying the terrain topology after it’s already complete and by hand. This is a repeatable process, but inefficient and wasteful when the path of the road needs to change mid-way through production.
My Solution
The system is three objects driven by one curve:
- Road Guide: A simple curve the user draws to set the path, flattened to ground level to normalize the distance measurements.
- Terrain: The geometry node system generates the ground and scatter.
- Road Surface: The road mesh itself, which is placed onto the finished terrain.
By creating a road path object as a curve, we can designate the space the road will occupy before the terrain is generated, and use it as an input to control the terrain’s height based on proximity to the guide curve. I like the word “carver” because that’s what the tool looks like it’s doing, but technically, the terrain is built around the road from the start.
This node chain takes the curve object of the road as an input and measures the proximity of points on a flat plane, the future terrain mesh. That information is passed to the terrain builder before any height is applied. Points on the road are assigned a single flat elevation, which fades out with distance from the center until natural hill values remain.
Building the Terrain
The terrain starts as two noise layers, broad hills and fine detail. They’re added together and controlled with an amplitude multiplier. Noise textures can be added or swapped to vary the terrain type. The grass, flower, bush and stone scatter all share the same distance measurement, so nothing spawns within X meters of the road’s center line.
Moving a point on the guide curve updates the terrain, the road surface and the scatter clearance together, live. You can control the midpoint of the road to place the road in a valley or on a ridge. See the hero media of this project to see this effect in action.
Beauty Render with Assets
