var density = 0.999;  
var airDens = 0.013;  
// In something like gram per cubic centimeter  
var flux : Vector3;  
var gravity = 9.81;  
var surfaceHeight = 0.0;  
var damper = 1.0;  
var thickness = 0.5;  
var normDrag = 0.0;  
var waterDrag = 0.99;  

function OnTriggerEnter (other : Collider) {  
    other.gameObject.SendMessage("YouSwim", true, SendMessageOptions.DontRequireReceiver);  
    other.gameObject.SendMessage("Water", transform, SendMessageOptions.DontRequireReceiver);  
    other.gameObject.SendMessage("Density", thickness, SendMessageOptions.DontRequireReceiver);  
}  

function OnTriggerStay (other : Collider) {  
    if (other.GetComponent(Rigidbody)) {  
       var size = other.bounds.size;  
       var volume : float = size.x*size.y*size.z;  
       var dens = other.rigidbody.mass/volume;  
       other.rigidbody.AddForce(transform.up * ((density-dens) * (surfaceHeight - other.transform.position.y) * damper / thickness - other.rigidbody.velocity.y/gravity) + flux/dens);  
       other.rigidbody.drag = waterDrag + (surfaceHeight - other.transform.position.y) * (waterDrag/gravity) + (0 - other.rigidbody.velocity.y) * (waterDrag/damper);  
       //other.rigidbody.AddTorque(Vector3.Slerp(other.rigidbody.angularVelocity, other.rigidbody.angularVelocity * -thickness, Time.deltaTime));  
       var colliders : Collider[] = Physics.OverlapSphere (other.transform.position, volume/(damper/dens*2));  
       for (var effect in colliders) {  
          if (effect.rigidbody && effect != other && effect.rigidbody.drag != 0.0) {  
             effect.rigidbody.AddForce(other.rigidbody.velocity * (damper/thickness) / effect.rigidbody.mass * Vector3.Normalize(other.rigidbody.velocity).magnitude * airDens);  
             var angl = (other.rigidbody.angularVelocity+other.rigidbody.velocity)/2;  
             effect.rigidbody.AddTorque(angl);  
          }  
       }  
    }  
}  

function OnTriggerExit (obj : Collider) {  
    other.gameObject.SendMessage("YouSwim", false, SendMessageOptions.DontRequireReceiver);  
    obj.rigidbody.drag = normDrag;  
}

// density here is killograms per cubic meter. Unity's world units are meters and mass is commonly assumed to be killograms  
   // Density of wood: 600 kg / cu.m  
   // Density of water 1000 kg / cu meter  
   // Density of iron 7000 kg / cu meter  
   // densityOfBody = b.mass / curBodiesVolume[i];  

var divider = 1.0;  

var airborneDrag = -1.0; //If left at -1 will use the Rigidbody Drag  
var fluidDrag = 0.0;  

private var fluidDensity = 1000.0;  
private var displacement = 0.0;  

private var myRenderer : Renderer;  
private var myRB : Rigidbody;  
private var myColliders : Array;  

private var timer = 0.0;  

function Start(){  
    var renderers = transform.root.gameObject.GetComponentsInChildren(Renderer);  
    var rendMax = Vector3(0,0,0);  
    for (var ren : Renderer in renderers){  
       if(ren.bounds.size.sqrMagnitude>rendMax.sqrMagnitude){  
          rendMax = ren.bounds.size;  
          myRenderer=ren;  
       }  
    }  
         
    if(myRB==null) myRB = GetComponent(Rigidbody);  
    if(myColliders==null) myColliders = GetComponentsInChildren(Collider);  
    for(var col : Collider in myColliders){  
       displacement += col.bounds.size.x*col.bounds.size.y*col.bounds.size.z;  
    }  
    displacement = displacement/divider;  
      
    if(airborneDrag<0)airborneDrag = myRB.drag;  
}  

function OnTriggerEnter(c : Collider){  
    if(c.tag=="fluid") myRB.drag=fluidDrag;  
      
}  
function OnTriggerStay(c : Collider){  
       if(myRenderer==null)return;  
       var timetemp = Time.realtimeSinceStartup;  
       if(c.tag=="fluid"){  
          var surfaceYPos = c.transform.position.y;  

          var bottom : Vector3 = transform.position;  

          for(var col : Collider in myColliders){  
             if(col==null) continue;  
             var temp = col.ClosestPointOnBounds(transform.position-Vector3(0,100,0));  
             if(temp.y<bottom.y) bottom = temp;  
          }  
                     
          var bottomToSurface : float = (surfaceYPos-bottom.y);  
            var bottomToCenter : float = (bottom - myRenderer.bounds.center).magnitude;  
            
           var pctSubmerged : float = Mathf.Clamp01(bottomToSurface/(bottomToCenter*2));  
          var force : Vector3 = displacement*fluidDensity*pctSubmerged*-1*Physics.gravity;  
          bottom = Vector3.Lerp(bottom,transform.position,0.75);  
          myRB.AddForceAtPosition(force,bottom);  
       }  
       timer += Time.realtimeSinceStartup-timetemp;  
}  

function OnTriggerExit(c : Collider){  
    if(c.tag=="fluid")   myRB.drag=airborneDrag;  
}