Directional

/**
 * Directional. 
 * 
 * Move the mouse the change the direction of the light.
 */

void setup() {
    size(640, 360, P3D);
    noStroke();
    fill(204);
}

void draw() {
    noStroke(); 
    background(0); 

    float dirY = (mouseY / (float)height - 0.5f) * 2.0f;
    float dirX = (mouseX / (float)width  - 0.5f) * 2.0f;

    directionalLight(204, 204, 204, -dirX, -dirY, -1); 

    translate(width / 2 - 100, height / 2, 0); 
    sphere(80); 

    translate(200, 0, 0); 
    sphere(80); 
}