用C#和WASM实现的赛车物理引擎，在Three.js中渲染

Build a browser-based vehicle physics demo. Write the car physics engine in pure C# and compile it to WebAssembly as the backend, and render the result with Three.js. Load a racing track as collidable meshes: grey stylized road surfaces, banked curves, ramps, tubes, steel gantries and cranes against a harbor skyline with a blue sky. Show a small white car from a chase camera behind it. The physics must handle wheel contact, grip on different surface zones (coloured patches such as sand or boost areas should change behavior), jumps, wall collisions and recovery after landing. Drive the car with keyboard input and show smooth camera follow. Keep the visuals simple and flat-shaded so the focus stays on movement. Done means the car runs laps through the track in the browser with stable, believable handling and no falling through the geometry.