Playground

Grow a city — or a race circuit — from one seed

This is the live street generator that ships in @jgengine/core, rendered in full 3D: streets, frontage building lots, traffic. Every drag regrows the whole city deterministically — same seed and sliders, same city, in the browser, in the editor, and in a shipped game.

World half-size260

Block size90

Winding0.15

Elevation0.35

Gridness0.85

Connectivity0.6

Branching0.25

Boulevards0.2

Sidewalk width2.2

Marking width0.18

Marking offset0

Dash length4.8

Dash gap4

Lot frontage12

Lot depth10

Sidewalk setback3

Plot spacing2

Plot variety0.5

Landmarks0.08

Block fill0.45

Focus junction (-1 = free)-1

46 streets · 262 buildings

Bake this exact layout into a game

bun packages/editor/src/mcp/cli.ts --game <id> --rpc '{"method":"generate_streets","seed":"vice-isle","mode":"net","halfX":260,"halfZ":260,"center":{"x":0,"y":0,"z":0},"params":{"gridness":0.85,"connectivity":0.6,"branching":0.25,"winding":0.15,"segmentLength":90,"boulevards":0.2,"elevation":0.35,"maxGrade":0.12}}' --save

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