Writing "Jump" from scratch

Currently this is what I've got for my Jump script.

Code (csharp):

1.  
2.             if(Input.GetButtonDown("Jump") )
3.             {
4.                 rigidbody.AddRelativeForce(transform.up * jumpForce);
5.            
6.                 Debug.Log ("Jumping");
7.             }
8.  

The problem is that my character can jump while it's still in the air. How might I go about checking if the character is still in the air?

 

The way I would detect if is is standing on something is to cast a raycast. If it hits something, allow the player to jump.

Here is the reference: http://docs.unity3d.com/Documentation/ScriptReference/Physics.Raycast.html

 

Interesting, why don't you try to apply this line only if the body is touching the ground?

 

Yes, that's the idea. Except I still want to disable jump even if the character is on a solid object that is not the "ground" such as a block or something.

Thank you for the raycast information. That looks mostly striaght forward to. Ill try it out.

 

Btw, you're mixing local and world coordinates.

 

Do you mean that the addrelativeforce is referencing "up" on the rigidbody instead of "up" in the game world?

 

Code (csharp):

1.  
2. // relative to rigidbody
3. addRelativeForce(x * Vector3.up);  // addRelativeForce does the transformation from world -> local
4. addForce(x * transform.up);  // transform.up does the transformation from world -> local
5.  
6. // relative to world
7. addForce(x * Vector3.up);  // no transformation
8.  
9. // neither, since you're transforming the coordinates *twice*
10. addRelativeForce(x * transform.up);
11.  
12.  

 

I'm sorry, I don't quite understand what it means when you type "world -> local"

I'm especially confused because what I have typed in is causing my character to jump as I expect it to.

 

Please bear in mind that using a simple Raycast to detect whether the player is grounded will cause problems when the ground isn't a flat surface. If you're walking over a small hole for example. You won't be grounded while walking over it, despite...well, walking over it. Same can apply if you're standing at the edge of something, depending on its collider.
I've read that using CheckCapsule() instead would be the way to go, which sounds logical. The only problem is that I cannot seem to get it working. It always returns true - even if I'm in midair - despite the measurements being correct (checked with Debug.DrawLine()).

 

World coordinates: "Up" means +y. Means in the directions of Vector3.up, ie: (0, 1, 0).

Local coordinates: "Up" is relative to the rotation of your transform. If you are laying on your back in bed, "up" to you would be toward the wall nearest your head. "Forward" would be the direction you're facing, ie: towards the ceiling.

A "transform" is used to transform world coordinates to local and vice versa. For the guy lying in bed, transform.forward = (0, 1, 0) = Vector3.up.

I'm guessing your character always stands "upright". So world or local make no difference in terms of "up", they will always be the same. Sometimes code works because of outside constraints or luck, it happens.

At any rate, you should probably google the difference between world and local coordinates before your luck runs out.

 

Ahh, wise words. Thank you. I want to program this correctly, so the correct way to do this would be to use Vector3.up right?

 

Update: This code below now works as expected. Ill use this until it gives me issues. Thanks for the help guys.

Code (csharp):

1.  
2. if (Physics.Raycast(transform.position, -Vector3.up, 1f))
3. {
4.     rigidbody.AddRelativeForce(Vector3.up * jumpForce);
5.     Debug.Log("Jumping.");
6. }
7. else
8. {
9.     Debug.Log("Can't Jump. Not Grounded.");
10. }
11.