varying float LightIntensity; 
varying vec3  MCposition;

uniform sampler3D Noise3;

uniform vec4  LightWoodColor;
uniform vec4  DarkWoodColor;
uniform float RingFreq;
uniform float NoiseScale;
uniform float NoiseMag;

void main()
{
    vec3 noisevec = NoiseMag * texture3D( Noise3, NoiseScale * MCposition ).rgb;
    vec3 location = MCposition + noisevec;

    float dist = sqrt(location.x * location.x + location.z * location.z);
    dist *= RingFreq;


    // create an up-down ramp:

    float r = fract(dist + noisevec[0] + noisevec[1] + noisevec[2]) * 2.0;
    if( r > 1.0 )
        r = 2.0 - r;
 
    vec4 color = mix( LightWoodColor, DarkWoodColor, r );

    color *= LightIntensity;
    
    gl_FragColor = vec4( color.rgb, 1. );
}