Ray through camera

Question

Hi all,

I have what I thought was some very simple code. I want to cast a ray through the camera to the global 0,0,0 position.

     void Update () {
         Ray ray = camera.ViewportPointToRay(new Vector3(0,0,0));
         Debug.DrawRay(ray.origin, ray.direction * camera.farClipPlane, Color.yellow);    
     }

This just seems to cast a ray along the bottom left frustrum line and has no bearing on camera position in relation to the zero position.

Any help would be great!

Answer 1

Best Answer

Answer by robertbu · Jul 03, 2014 at 06:45 AM

Viewport coordinates start at (0,0) in the bottom left corner, and go to (1,1) in the upper right. So your code is casting a ray into the scene from the bottom left of the camera viewport. It seems you want to cast from the center of the camera to the world origin. You can use a version of the Raycast that takes a position and a direction:

 Vector3 origin = camera.transform.position;
 Vector3 direction = -transform.position;   

 if (Physics.Raycast(origin, direction)) {
     // Do something
 }

And the Debug.DrawRay() would be:

 Debug.DrawRay(origin, direction);

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thehen2 · Jul 03, 2014 at 09:28 AM 0

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Ah thanks, that makes a lot of sense, I was misunderstanding the use of ViewportPointToRay.

Ray through camera

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