potato3.js

// Create an heightmap
var heightmap = new BABYLON.DynamicTexture("heightmap", {width:1024, height:1024}, scene);   
heightmap.update();
var context = heightmap.getContext();

// Plug the heightmap in the node material
var textureBlocks = matCap.getTextureBlocks().filter(b => b.name === "HeightMap");

if (textureBlocks && textureBlocks.length) {
    textureBlocks[0].texture = heightmap;
}