k3d/share/shaders/k3d_skin1.sl:106:  float costheta = -v1 . v2;
k3d/share/shaders/k3d_skin1.sl:107:  return (1. - g*g) / pow(1. + g*g - 2.*g*costheta, 1.5);
k3d/share/shaders/k3d_skin2.sl:25:	float costheta = -v1 . v2;
k3d/share/shaders/k3d_skin2.sl:26:	return (1. - g*g) / pow(1. + g*g - 2.*g*costheta, 1.5);
k3d/share/shaders/k3d_skymetal.sl:26:	float costheta;
k3d/share/shaders/k3d_skymetal.sl:35:	costheta = normalize (reflect (I, Nf)) . up;
k3d/share/shaders/k3d_skymetal.sl:37:	if (costheta >= 0.0)
k3d/share/shaders/k3d_skymetal.sl:38:		refl = mix (sky_horiz, sky_zenith, costheta);
k3d/share/shaders/k3d_skymetal.sl:40:		refl = mix (land_horiz, land_zenith, -costheta);
k3d/share/shaders/k3d_watercolor.sl:22:	float costhetai = abs(nI . nN);

k3d/share/shaders/k3d_watercolor.sl:23:	float thetai = acos(costhetai);

