light arealight(color lightcolor = color(1,1,1);
		float intensity = 1;
		string maplist = "";
		float numsamples = 1;
		point Pl1 = point "shader" (0, 0, 0);
		point Pl2 = point "shader" (1, 0, 0);
		point Pl3 = point "shader" (0, 1, 0);
		point Pl4 = point "shader" (1, 1, 0);
		float shadowbias = 0.001;
		float gapbias = 0.01)
{
    varying float attenuation;
    
    /* Base illumination at average of light positions */
    illuminate ((Pl1 + Pl2 + Pl3 + Pl4) * 0.25) {
	attenuation = shadow(maplist, Ps, "source", Pl1, Pl2, Pl3, Pl4,
	    "samples", numsamples, "bias", shadowbias, "gapbias", gapbias);
	Cl = lightcolor * intensity * (1-attenuation);
    }
}