用Three.js做的薄雾密林：数千棵树与海量实例化草丛

Build a highly detailed procedural forest in Three.js that the viewer explores from a first-person camera. Fill a large terrain with thousands of individual trees of varied shapes, millions of instanced grass clumps and tens of thousands of ferns, plus moss-covered logs, small white flowers and a worn dirt path winding between the trunks. Use custom GLSL shaders for wind-swayed grass and foliage, soft misty fog that fades distant trees into pale green haze, and filtered light coming through the canopy. Keep the palette natural: deep greens, brown bark, warm earth tones and a bright overcast sky. Use instancing and level of detail so it runs smoothly in a browser. Let the camera walk along the path and tilt up to show branches and leaves against the sky. Done means a web page that loads and runs in real time with convincing density and depth.