Check out example codes for "draw sphere cast unity with program". It will help you in understanding the concepts better.

Code Example 1

void RenderVolume(Vector3 p1 , Vector3 p2 , float radius , Vector3 dir, float distance )
         {
             if (!shape)
             { // if shape doesn't exist yet, create it
                 shape = GameObject.CreatePrimitive(PrimitiveType.Cube).transform;
                Destroy(shape.GetComponent<Collider>()); // no collider, please!
                 shape.GetComponent<Renderer>().material = mat; // assign the selected material to it
             }
             Vector3 scale ; // calculate desired scale
             float diam  = 2 * radius; // calculate capsule diameter
             scale.x = diam; // width = capsule diameter
             scale.y = Vector3.Distance(p2, p1) + diam; // capsule height
             scale.z = distance + diam; // volume length
             shape.localScale = scale; // set the rectangular volume size
                                       // set volume position and rotation
             shape.position = (p1 + p2 + dir.normalized * distance) / 2;
             shape.rotation = Quaternion.LookRotation(dir, p2 - p1);
             shape.GetComponent<Renderer>().enabled = true; // show it
         }
 
         void HideVolume()
         { // hide the volume
             if (shape) shape.GetComponent<Renderer>().enabled = false;
         }
         private Transform shape ; 
         public float range  = 10; // range of the capsule cast
         private float freeDistance = 0;
         void Update()
         {
                   if (Input.Get$$anonymous$$ey("p"))
             { // while P pressed...
                 RaycastHit hit;
                 CharacterController charContr = GetComponent<CharacterController>();
                 var radius = charContr.radius;
                 // find centers of the top/bottom hemispheres
                 Vector3 p1   = transform.position + charContr.center;
                 var p2 = p1;
                 var h = charContr.height / 2 - radius;
                 p2.y += h;
                 p1.y -= h;
                 // draw CapsuleCast volume:
                 RenderVolume(p1, p2, radius, transform.forward, range);
                 // cast character controller shape range meters forward:
                 if (Physics.CapsuleCast(p1, p2, radius, transform.forward,out hit, range))
                 {
                     // if some obstacle inside range, save its distance 
                     freeDistance = hit.distance;
                 }
                 else {
                     // otherwise shows that the way is clear up to range distance
                     freeDistance = range;
                 }
             }
             if (Input.Get$$anonymous$$eyUp("p"))
             {
                 HideVolume(); // hide volume when P is released
             }
         }

Learn ReactJs, React Native from akashmittal.com