float pulse(float freq) {
    return 0.5 + 0.25 * sin(iGlobalTime * freq);
}
float varyingTime(float minv, float maxv, float m) {
    float range = (maxv - minv);
    return (minv + range/2) + (range/2) * sin(iGlobalTime * m);
}
float wrappingTime(float minv, float maxv, float m) {
    float range = (maxv - minv);
    return (minv + range/2) + (range/2) * mod(iGlobalTime * m, 1);
}
float getProceduralColors(inout vec3 diffuse, inout vec3 specular, inout float shininess) {

    float size = 0.6;
    if (abs(_modelNormal.y) > size) {
        discard;
    }
    float c = texture(iChannel0, _texCoord0.xy).r;
    diffuse = vec3(0.5, 1.0, 0.8) * c;
    if (abs(wrappingTime(-0.5, 1.0, 0.2) - c) > 0.1) {
        discard;
    }
    return 0.0;
}