varying float LightIntensity; 
varying vec3  MCposition;
varying vec3  ECposition;

uniform vec4 SkyColor;
uniform vec4 CloudColor;
uniform float Bias;
uniform sampler3D Noise3;

void main()
{
	vec4  noisevec  = texture3D( Noise3, MCposition );

	float intensity = ( noisevec[0] + noisevec[1] + 
                       noisevec[2] + noisevec[3] );

	vec3 color   = mix( SkyColor.rgb, CloudColor.rgb, clamp( Bias+intensity, 0., 1. ) ) * LightIntensity;

	if( ECposition.y >= 0. )
		gl_FragColor = vec4(color, 1.0);
	else
		gl_FragColor = vec4( 0., 0., 0., 1. );

}