// Calculate ray direction
    float3 rayDir = normalize(fragPos - camPos);

    // half extents of cube
    float3 halfExtents = cubeSize * 0.5;

    // bounds of the cube
    float3 cubeMin = cubeCenter - halfExtents;
    float3 cubeMax = cubeCenter + halfExtents;

    // Ray-box intersection -  Slab method
    float3 tMin = (cubeMin - camPos) / rayDir;
    float3 tMax = (cubeMax - camPos) / rayDir;

    // Ensure tMin < tMax
    float3 t1 = min(tMin, tMax);
    float3 t2 = max(tMin, tMax);

    // Nuum of intersections (entry n exit points)
    float tNear = max(max(t1.x, t1.y), t1.z);
    float tFar = min(min(t2.x, t2.y), t2.z);

    // Check if intersection
    bool intersects = (tNear <= tFar) && (tFar >= 0.0);

    float3 normal= float3(0,0,0);

    if (intersects)
    {
        float3 intersectPoint = camPos + tNear * rayDir;
        float3 closestPoint = clamp(intersectPoint, cubeMin, cubeMax);

        // Normal at the closest point
        float3 diff = closestPoint - cubeCenter;

        normal = float3(0, 0, 0);

        // Determine face of the the closest point
        if (abs(diff.x) > abs(diff.y) && abs(diff.x) > abs(diff.z))
            normal = float3(sign(diff.x), 0, 0);
        else if (abs(diff.y) > abs(diff.x) && abs(diff.y) > abs(diff.z))
            normal = float3(0, sign(diff.y), 0);
        else
            normal = float3(0, 0, sign(diff.z));

    }
    else
    {
        //zero normal if no intersection
        normal = float3(0, 0, 0);
    }



float dotP= dot(otherNormal,normal);
result= step(dotP,thres);

if(!invert)
    result= 1-result;