Wrong contact resutls with BVHModels and negative security margin

[maxwave11]

Hi!

Given 2 physically intersecting BVHModels :

• big cube with edge size = 2 with center at (0,0,0)
• small cube with edge size = 1

models.zip

From images above it's obvious thtat small cube penetrates to another with at least 0.3 and even more than 0.5 distance.
But I have no results when testing with security margin = -0.5 and even =-0.3.

Here's my tests results:

Security margin: -0.5
no results 

Security margin: -0.3
no results 

Security margin: -0.2
Penetration depth: -0.775341
Distance between the shapes including the security margin: -0.975341
Witness point on shape1:     -0.5 0.016894        1
Witness point on shape2:     -0.5 0.016894        1
Normal: 0 0 1

Security margin: 0
Penetration depth: -0.775341
Distance between the shapes including the security margin: -0.775341
Witness point on shape1:     -0.5 0.016894        1
Witness point on shape2:     -0.5 0.016894        1
Normal: 0 0 1

Security margin: 0.1
Penetration depth: -0.775341
Distance between the shapes including the security margin: -0.675341
Witness point on shape1:     -0.5 0.016894        1
Witness point on shape2:     -0.5 0.016894        1
Normal: 0 0 1

Security margin: 0.5
Penetration depth: 0.5-----------------------Why value changed?
Distance between the shapes including the security margin: 1
Witness point on shape1:       -1        0 0.724659
Witness point on shape2:     -0.5        0 0.724659
Normal: 1 0 0

Here's my testing code:

shared_ptr<BVHModelBase> loadMesh(const char* file_name) {
    NODE_TYPE bv_type = BV_AABB;
    MeshLoader loader(bv_type);
    BVHModelPtr_t bvh = loader.load(file_name);
    return bvh;
}

int main() {
    shared_ptr<BVHModelBase> shape1 = loadMesh("obj1.obj");
    shared_ptr<BVHModelBase> shape2 = loadMesh("obj2.obj");

    auto* obj1 = new CollisionObject(shape1);
    auto* obj2 = new CollisionObject(shape2);

    CollisionRequest col_req;
    col_req.security_margin = -0.3;

    CollisionResult col_res;

    cout << "Security margin: " << col_req.security_margin << "\n";
    // Collision call
    collide(obj1, obj2, col_req, col_res);
    cout << "Collision? " << col_res.isCollision() << "\n";
    if (col_res.isCollision()) {
        Contact contact = col_res.getContact(0);

        cout << "Penetration depth: " << contact.penetration_depth << "\n";
        cout << "Distance between the shapes including the security margin: " << contact.penetration_depth + col_req.security_margin << "\n";
        cout << "Witness point on shape1: " << contact.nearest_points[0].transpose() << "\n";
        cout << "Witness point on shape2: " << contact.nearest_points[1].transpose() << "\n";
        cout << "Normal: " << contact.normal.transpose() << "\n";
    }

    col_res.clear();

    return 0;
}

Am I correct understand security margin (-0.3) concept?

Also I noticed, that penetration depth changed at some moment.

Could you please explain why I'm getting such results. Should I tune collision request to improve collision detection precision?
I want to test collisions with negative and positive security margin (clash detection) with arbitrary meshes (including concave). Probably my NODE_TYPE is not correct fot this purpose? How can I understand which NODE_TYPE I should use for my purposes?

Thank you in advance!