Three.js MeshPhongMaterial doesn't seem to be affected by non-ambient lights

Question

I have a function which graphs a pair of arrays as a double-sided surface. I have been using threejs for a few weeks, but never with a custom shape so I thought that might be related to the issue. I didn't find any internet answers that helped, although I tried many, so here I am.

I have these two pieces of code which are relevant, but the JsFiddle has the whole thing.

var ambient = new THREE.AmbientLight( 0x444444 );
scene.add( ambient );

var spotLight = new THREE.DirectionalLight( 0xffffff );
spotLight.position.set( 0, 1, 1 ).normalize();
scene.add(spotLight);

and

function graph(array1, array2)
{

    var particleCount = array1.length*array2.length,
        particles = new THREE.Geometry(),
        pMaterial = new THREE.MeshPhongMaterial({
            side: THREE.DoubleSide,
            shading: THREE.SmoothShading
        });

    // now create the individual particles
    for (var p = 0; p < particleCount; p++) {


    var row = (p%array1.length),
        col = Math.floor(p/array1.length),
        pX = 2*row - array1.length,
        pY = 2*col - array2.length,
        pZ = (array1[row])*(array2[col]),
        particle = new THREE.Vector3(pX, pZ, pY);

    // add it to the geometry
    particles.vertices.push(particle);
    if (row != 0 && col != 0)
    {
        particles.faces.push( new THREE.Face3( col * array1.length + row, col * array1.length + row - 1, (col - 1) * array1.length + row) );
        particles.faces.push( new THREE.Face3( (col - 1) * array1.length + row, col * array1.length + row - 1, (col - 1) * array1.length + row - 1) );
    }
}

// create the particle system
var particleSystem = new THREE.Mesh(
    particles,
    pMaterial);

// add it to the scene
scene.add(particleSystem);

onRenderFcts.push(function(){
    var angle   = Date.now()/10000 * Math.PI;
    particleSystem.rotation.y   = angle;        
})

}

https://jsfiddle.net/6Lp74xdn/1/

I guess I have just run out of ideas on what could be the reason the directional light doesn't illuminate the surface.

Answer 1

After you generated the vertices and faces you need to call computeFaceNormals() .

So, just add particles.computeFaceNormals(); at the end of your graph function.