Blending COPs SDFs into 3D Volume

        float blend = chf('blend');

function float sintersect(float d1,  d2, k){
    float h = clamp(0.5 - 0.5 * (d2 - d1) / k, 0.0, 1.0);
    return lerp(d2, d1, h) + k * h * (1.0 - h);
}

float d_0 = volumesample(1, 0, v@P);
float d_1 = volumesample(1, 1, v@P);

f@d = sintersect(d_0, d_1, blend);