Detect tap on a sphere in unity - unity3d

Question

I want to detect a tap on sphere. I have searched on google and many approaches like ontriggerenter() and using ray cast etc were found.
But what I want to get some values also that where user has touched on ball.
Like if the center of a sphere is x=0, y=0. then I should got positive x and y when user touch upper right corner of sphere.
It is not necessary to get exactly this value, Value can be anything but by these value I should be able to know that user has tapped on one of these 8 portions of ball.
upper right near center of circle
lower right near center of circle
upper left near center of circle
lower left near center of circle
upper right near corner of circle
lower right near corner of circle
upper left near corner of circle
lower left near corner of circle

Answer 1

You can use the methods you found, with raycasting you will get the exact position of the tap. Then you have to transform the centerpoint and the tap position of the sphere to screenspace coordinates. Then you can get the difference between those vectors to get the direction and distance from the center.
PS: Do circles have corners?
you need to have a GameObject with a Collider attatched to it which is set to "Is Trigger". And a script containing following code.
void OnMouseDown()
{
Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
RaycastHit hit;
//hits for sure, because we are in the click event
Physics.Raycast(ray, out hit);
Vector3 hitOnScreen = Camera.main.WorldToScreenPoint(hit.point);
Vector3 centerOnScreen = Camera.main.WorldToScreenPoint(transform.position);
Vector3 offset = hitOnScreen - centerOnScreen;
if(offset.x > 0 && offset.y > 0)
{
Debug.Log("upper right");
}else if(offset.x < 0 && offset.y > 0)
{
Debug.Log("upper left");
}else if(offset.x > 0 && offset.y < 0)
{
Debug.Log("lower right");
} else //if(offset.x < 0 && offset.y < 0)
{
Debug.Log("lower left");
}
}
For the distance to the center it is getting more complicated.
We have to get a vector perpendicular to the from the camera to the center and scale this to the propper size. If we add this to the center and transform it into screenspace we will have the maximum magnitude a point on the surface of the sphere could reach.
Vector3 perpendicular = Vector3.Cross(transform.position - Camera.main.transform.position, Vector3.one);
Vector3 maxDistToCenter = transform.position + (perpendicular.normalized * (transform.lossyScale.x * 0.5f));
Vector3 maxDistToCenterOnScreen = Camera.main.WorldToScreenPoint(maxDistToCenter);
float maxDist = (maxDistToCenterOnScreen - centerOnScreen).magnitude;
float dist = offset.magnitude;
if (dist < maxDist * 0.5f) // 50% of the way not the area
{
Debug.Log("inner 50%");
}
else
{
Debug.Log("outer 50%");
}
Combining both grant you the ability to evaluate any point on the sphere in angle and distance to the center compared with the maximum distance.
If you just want to apply force to the point clicked, you just need a ridgit body and raycasting. This oficial Unity tutorial will explay it.
Maybe you have to combine both answers, but I think the Unity tutorial is sufficient for your needs.
PS: Please ask questwions with the final goal you want to reach and not just a step you think is needed to get the job done.

Answer 2

You dont need to se raycasts, you can use "OnMouseDown".
Documentation here: http://docs.unity3d.com/ScriptReference/MonoBehaviour.OnMouseDown.html
Note: your object needs a collider in order for this to work.