javascript - How to change face color in Three.js

Question

I am attempting to change the color on a single face of a mesh. This is in a WebGL context. I can change the entire mesh color, just not a single Face. Relevant code below:

// Updated Per Lee!

var camera = _this.camera;      
var projector = new THREE.Projector();
var vector = new THREE.Vector3( ( event.clientX / window.innerWidth ) * 2 - 1,                                  - ( event.clientY / window.innerHeight ) * 2 + 1, 0.5 );
projector.unprojectVector( vector, camera );

var ray = new THREE.Ray( camera.position, vector.subSelf( camera.position ).normalize() );
var intersects = ray.intersectObjects( kage.scene.children );

if ( intersects.length > 0 ) {
    face = intersects[0].face;
    var faceIndices = ['a', 'b', 'c', 'd'];         
    var numberOfSides = ( face instanceof THREE.Face3 ) ? 3 : 4;
    // assign color to each vertex of current face
    for( var j = 0; j < numberOfSides; j++ )  {
        var vertexIndex = face[ faceIndices[ j ] ];
    // initialize color variable
    var color = new THREE.Color( 0xffffff );
    color.setRGB( Math.random(), 0, 0 );
    face.vertexColors[ j ] = color;
    }
}

I also initialize the object, in this case a Cube as follows:

// this material causes a mesh to use colors assigned to vertices
var material = new THREE.MeshBasicMaterial( { 
    color: 0xf0f0f0, 
    shading: THREE.FlatShading,
    vertexColors: THREE.VertexColors 
});

var directionalLight = new THREE.DirectionalLight(0xEEEEEE);
directionalLight.position.set(10, 1, 1).normalize();
kage.scene.add(directionalLight);

var cube = new THREE.Mesh(new THREE.CubeGeometry(300, 300, 300,1,1,1), material);
cube.dynamic = true;
kage.scene.add(cube);

Changing the material makes the cube white regardless of the light color. The intersection logic still works, meaning i select the correct face, but alas the color does not change.

I'm new to Stackoverflow [well asking a question that is, so hopefully my edits are not confusing]

Answer 1

• Update library to r53.
• Add vertexColors: THREE.FaceColors in material.

• And finally use face.color.setRGB( Math.random(), Math.random(), Math.random()).

  Now no need to traverse loop for 4 sides (a,b,c,d) for THREE.Face4 or 3 sides (a,b,c) for THREE.Face3.

  This works in both WebGL and Canvas rendering.

Example

three.js r53