parametric-terrain.js

function parametricTerrain ([ u, v ]) {
  // Turn 0..1 to -1..1
  const x = u * 2 - 1;
  const z = v * 2 - 1;
  
  // Find height at this 2D coordinate
  const y = calculateTerrainHeight(x, z);
  
  // Return the 3D surface point
  return [ x, y, z ];
}