Decrease ExplosionForce and damage continously by distance


I am struggeling on how to apply damage and force by the distance from the center of the explosion.
The distance of each founded collider is converted to a ratio, with 0 being at the edge of the explosion radius / away from the explosion center and 1 at the explosion center. The applied force and damage should be multiplied with that value, but I am doing wrong calculations.

This is the OnCollisionEnter function of the Proximity Mine:

 void OnCollisionEnter(Collision hit){
    Collider[] col = Physics.OverlapSphere(transform.position, explosionRadius, detectionLayer);

    foreach(Collider c in col){
        float dist = Vector3.Distance(transform.position, c.transform.position);
        float ratio = 0;
        ratio = Mathf.InverseLerp(explosionRadius, dist, ratio);

        if(c.gameObject.layer != LayerMask.NameToLayer("Projectile")){
            c.transform.SendMessage("ReceiveDamage", damage*ratio);
            c.transform.position, explosionRadius, 30.0F, ForceMode.VelocityChange);

you are using lerp wrong the last argument is meant to be a value between 0 and 1 but in your script it is always 0. try this for the ratio. forget about using lerp and try this for the ratio

float ratio = Mathf.Clamp01( 1 - dist / explosionRadius );

A simple model for an explosion would be that the strength of the explosion decreases with the Inverse-Square law. It won’t be a physically exact model, but close enough for a game. It would be something like:

float ratio = 1 / (transform.position - c.transform.position).sqrMagnitude;

Note that it won’t be at 0 at the edge of your radius (in fact, it won’t be exactly zero ever). But if the radius is small enough or the explosion is weak enough, the result at the edge will be pretty small

Edit: if you want to use a Lerp absolutely: it would go like this:

ratio = Mathf.InverseLerp(0, explosionRadius, dist);