The Lumen bike from simple shapes
Open the scene tree: the bike is a Group holding named meshes. The status bar shows 14 draw calls, one per mesh. This is the geometry only; paint and the finished parts arrive in later phases.
A bicycle is tubes, rings and a few blobs. You build the whole Lumen frame from cylinders, tori and a capsule, aim each tube between two points, group paired parts, and count what each part costs.
Change the code and press Run (Ctrl+Enter). Predict what will happen first, then break it on purpose and read what changes. Your edits are saved and match the lesson page.
Ready for more? This phase has 4 hands-on exercises with automatic checks.
Practice questions
Write the code in the editor, run it, then open the model answer to compare.
Add a kickstand tube from the bottom bracket to (−0.2, 0, 0) with radius 0.012 and print how many triangles it adds.
Make tubeBetween refuse a zero-length tube: it should throw a helpful error naming the tube.
Explain it without notes
How do you place a cylinder so its two ends are exactly on two points?
Why are P.bottomBracket.clone().setZ(z) and not P.bottomBracket.setZ(z) used for the stays?
Console
Nothing logged yet.Expected console output
down tube 64 triangles
top tube 64 triangles
seat tube 64 triangles
fork 64 triangles
chain stay 128 triangles
seat stay 128 triangles
rear wheel 768 triangles
front wheel 768 triangles
seat post 64 triangles
saddle 216 triangles
handlebar 48 triangles
drawn: 14 draw calls, 2632 triangles