vec4 spotLightSubroutine(vec4 N, vec4 worldPosition, vec3 worldNormal)
{
    // Insert code for Section 3.5 here.

    vec4 L = (pointLight.pointPosition - worldPosition) / normalize(pointLight.pointPosition - worldPosition);
    float cos_theta = max(0, dot(-L, pointLight.pointPosition));

    float lambda = 0.;
    if (cos_theta > cos(genericLight.spotInnerConeAngleDegrees)) {
        lambda = 1.0;
    } else if (cos_theta >= cos(genericLight.spotOuterConeAngleDegrees)) {
        lambda = (cos_theta - cos(genericLight.spotOuterConeAngleDegrees) ) / (cos(genericLight.spotInnerConeAngleDegrees) - cos(genericLight.spotOuterConeAngleDegrees));
    }

    return vec4(lambda);
    //return vec4(0.);
}