How to fix a fast object not colliding with things

If two objects are moving "fast" towards each other, it may happen that the physics engine does not detect a collision and the objects pass through each other. This gets more likely the thinner/smaller the objects are and the faster they move. It could already happen when a player runs against a wall.

To fix this problem a physical raytrace can be done between the last position and the current position to check if there was any collider and the object can be moved backwards.

Example:

// data members:

Urho3D::Vector3 pos_last;
Urho3D::RigidBody* body;


// in the update/movement code:

// get the center position of the object, this one is 2 units high and the
// "0-point" is at the bottom/feet so 1 unit up to get the center
Vector3 object_pos=body->GetPosition()+Vector3(0,1,0);  
PhysicsRaycastResult result;
Ray ray(pos_last,object_pos-pos_last);
float l=(object_pos-pos_last).Length();
// make a raycast from the position in the last frame towards the current one if
// this object moved at least 0.5 units
if(l>0.5)
{
    globals::instance()->physical_world->SphereCast(result,ray,0.2,l,2);
    if(result.distance_<=l)           // if there is something between the last and current position
        body->SetPosition(pos_last);  // move the object back (could also be positioned at the ray hit)
}
pos_last=object_pos;

Also see

https://urho3d.github.io/documentation/HEAD/_physics.html#Physics_Movement which describes an easily-applied solution using CCD.

To prevent tunneling of a fast moving rigid body through obstacles, continuous collision detection can be used.