Bakes a procedural mountain range into a single mesh, returned in a THREE.Group.
Domain-warped, derivative-damped noise shapes the ridges; thermal erosion relaxes
steep slopes. A TSL material shades grass, rock and snow from altitude and slope.
The baked grid is available through TerrainGenerator#sampleHeight for placing a forest or other objects on the terrain.
const terrain = new TerrainGenerator( { seed: 1 } );
scene.add( terrain.build() );