April 18, 2026
When “simple” meets the road rage
The simple geometry behind any road
Dev says roads are circles + lines; readers demand spirals, slopes, and speed
TLDR: A dev pitched roads built from lines and circles, using cross-sections to keep things smooth. Commenters erupted, calling for clothoids (gradually tightening curves), lane-width tweaks, drainage slopes, and speed effects—turning a clean theory into a messy, must-have reality check for anyone building roads in games.
A game dev dropped a bold claim: you can build any road with simple geometry—just lines and perfect circles—by stitching together cross-sections called “profiles.” It’s clean, elegant, and very “math-core.” The crowd? They slammed the brakes hard.
Top comment fired the first flare: “You’re missing clothoids,” said one reader, pointing to the real-world “Euler spiral”—a curve that gently tightens instead of snapping from straight to circular. It’s how many highways and racetracks keep drivers comfy and cars planted. Others piled on with real-world receipts: one user linked a hairpin where lane widths change with the bend, because sometimes geometry has to share a lane with physics and paint. And the drainage police showed up: “Where’s the slant so rain doesn’t puddle?” joked another, claiming they were “salt-water-aquaplaning” in advance. For the performance-minded, speed and car motion (“pitch and yaw”—how the car tilts and turns) were waved like red flags: if you ignore them, “simple it is not.”
Between the math purists and the asphalt realists, the thread became a showdown: neat circles vs. messy reality. A cryptic drive-by—“many are yet to catch up”—added spice without substance, and a few laughed that the post is how you get road art, not road feel. Verdict from the comments: great start, but if you don’t spiral, slope, and speed-check, your “simple” road might drive like a ruler.
Key Points
- •The article uses a profile-based representation (cross-sections) to define road geometry for procedural generation.
- •It prefers constructing roads from lines and circular arcs rather than expanding a centerline Bezier spline.
- •A circle property (equally spaced points along a radius trace concentric arcs) lets the solution generalize across a profile.
- •The core geometric task is to connect two points with specified tangents using an arc tangent at both ends.
- •Because a single tangent arc often isn’t feasible, the approach allows line extensions with arcs to achieve smooth connections.