precision lowp float;

varying vec4 v_normal;

void main() {
  // ambient lighting (global illuminance)
  vec3 ambient = vec3(0.5, 0.5, 0.5); // color - grey

  // diffuse (lambertian) lighting
  // lightColor, lightSource, normal, diffuseStrength
  vec3 normal = normalize(v_normal.xyz);
  vec3 lightColor = vec3(1.0, 1.0, 1.0); // color - white
  vec3 lightSource = vec3(1.0, 1.0, 1.0); // coord - (1, 0, 0)
  float diffuseStrength = max(0.0, dot(lightSource, normal));