Unity camera trembling on collision - unity3d

Question

The script works perfectly, exactly as it should, except when zooming too much and the SphereCast collides with the mesh. When it hits a mesh, I want the camera to just stop, and not try to go through the mesh.
if(Input.touchCount == 2)
{
Touch first = Input.GetTouch(0);
Touch second = Input.GetTouch(1);
origin = mainCamera.transform.position;
direction = mainCamera.transform.forward;
RaycastHit hit;
if(Physics.SphereCast(origin, sphereRadius, direction, out hit, maxDistance))
{
inCollision = true;
}
else
{
inCollision = false;
}
if(first.phase == TouchPhase.Began || second.phase == TouchPhase.Began)
{
initialDistance = Vector3.Distance(first.position, second.position);
}
if(first.phase == TouchPhase.Moved || second.phase == TouchPhase.Moved)
{
movedDistance = Vector3.Distance(first.position, second.position) - initialDistance;
if(inCollision)
{
movedDistance = -Mathf.Abs(movedDistance);
}
mainCamera.transform.localPosition = new Vector3(0, 0, mainCamera.transform.localPosition.z + movedDistance * zoomSensitivity * Time.deltaTime);
initialDistance = Vector3.Distance(first.position, second.position);
}
}
I tried to:
Set movedDistance to 0 when SphereCast hits the mesh;
Clamp mainCamera.transform.localPosition.z to mainCamera.transform.localPosition.z, but only when SphereCast hits the mesh, so the z doesn't zoom more than it's current value.

Answer 1

As commented before you all the time move forward, collide, move backwards, don't collide anymore, move forward etc.
You could probably rather not move backwards but check if you would collide if you would move and do not move at all in this case:
if(first.phase == TouchPhase.Began || second.phase == TouchPhase.Began)
{
initialDistance = Vector3.Distance(first.position, second.position);
}
else if(first.phase == TouchPhase.Moved || second.phase == TouchPhase.Moved)
{
movedDistance = Vector3.Distance(first.position, second.position) - initialDistance;
// Only check until here if you WOULD collide
origin = mainCamera.transform.position;
var targetPosition = origin + mainCamera.transform.forward * movedDistance * Time.deltaTime * zoomSensitivity;
direction = mainCamera.transform.forward;
// only move if there WILL BE no collision
if(!Physics.SphereCast(targetPosition, sphereRadius, direction, out var hit, maxDistance))
{
mainCamera.position = targetPosition;
}
initialDistance = Vector3.Distance(first.position, second.position);
}
From the example for SphereCast you can see that you could even take the hit.distance into account in order to at least move the camera the closest possible.