How do I rotate a Vector3 direction by another direction

I want to rotate a Vector3 by the grounds normal. How would I do this?

 

transform.right ?

 

That not what im looking for at all

 

Code (CSharp):

1.  
2.     void UpdateRotation()
3.     {
4.         RaycastHit hit;
5.         if(Physics.Raycast(transform.position, -transform.up, out hit, 10))
6.         {
7.             transform.rotation = Quaternion.LookRotation(hit.normal);
8.         }
9.     }

? O: <

 

Vector3.right is always the same direction.
So don't confuse me by changing it's angle in the drawing ;-;

 

I'm making a Vector 3 from the players input and need it rotated by the normal the player is standing on
So I can apply force on the player that is consistent with the slope

 

Are you in a 2D game or a 3D game? This is important because in 3D you have the z component to think about which means you can rotate into or out of the screen.

In 2D, you need to determine which way you need to rotate the normal.

Code (csharp):

1. Vector3 normal = someNormal;
2. // Rotate around z axis, Correct if we are moving left.
3. Vector3 rotatedLeft = Quaternion.Euler(0f, 0f, 90f) * normal;
4. // Correct if we are moving right.
5. Vector3 rotatedRight = Quaternion.Euler(0f, 0f, -90f) * normal;

 

It's 3D

 

Check the slope using raycast, then move the player relative of that rotation.

 

That not what im trying to do at all

 

Don't you want to move & rotate the player RELATIVE to the normal beneath the player? e__o

 

no

 

Can you visualize it? x_x

 

I'll try

 

The player pressed the right key, so a blue line comes out to the right, level with the ground
BUT the cube has nothing to do with it, the cube can be at any rotation

The player can also press 2 keys together like forward and sideways to go diagonal

 

And the blue line indicates the direction that it's translating towards?

 

The blue line is just a blue line for now
Its shooting out to the right because the player pressed the right key

 

I'm going to sleep, I'll try to help u tomorrows

 

Alright

 

I found the answer here
http://answers.unity3d.com/questions/10323/calculating-a-movement-direction-that-is-a-tangent.html

Code (CSharp):

1.     Vector3 surfaceNormal; // Get the normal value on collision;
2.     Vector3 myDirection; // player direction in X-Z space;
3.    
4.     void FixedUpdate(){
5.     Vector3 temp = Vector3.Cross(surfaceNormal, myDirection);
6.     Vector3 myDirection = Vector3.Cross(temp, surfaceNormal);
7.     }

surfaceNormal is the raycast hit.normal
and myDirection is the player input

 

This is the real correct answer. The one above only works properly on flat ground

Vector3 tiltInput = new Vector3(Input.GetAxis("Horizontal"), 0 , Input.GetAxis("Vertical"));
Vector3 projForward = transform.forward - (Vector3.Dot(transform.forward, hit.normal) * hit.normal);
Vector3 rayDirection = Quaternion.LookRotation(projForward, hit.normal) * tiltInput;
rayDirection.Normalize();

Debug.DrawRay(transform.position, rayDirection * 10, Color.magenta);

 

This works too:

Code (CSharp):

1.  
2. Vector3 tiltInput = new Vector3 (Input.GetAxis ("Horizontal"), 0, Input.GetAxis ("Vertical"));
3. // Vector3 projForward = transform.forward - (Vector3.Dot (transform.forward, hit.normal) * hit.normal);
4. Vector3 rayDirection = Quaternion.LookRotation (transform.forward, hit.normal) * tiltInput;
5. rayDirection.Normalize ();
6.  
7. Debug.DrawRay (transform.position, rayDirection * 10, Color.magenta);
8.  

 

This also works but it's relative to the world x, z axis (but perhaps you dont care):

Code (CSharp):

1.  
2. Vector3 tiltInput = new Vector3 (Input.GetAxis ("Horizontal"), 0, Input.GetAxis ("Vertical"));
3. Vector3 rayDirection = Vector3.Cross (hit.normal, tiltInput);
4. rayDirection = Vector3.Cross (rayDirection, hit.normal); // you can remove this line if you swap "Horizontal" and "Vertical"
5. rayDirection.Normalize ();
6.  
7. Debug.DrawRay (transform.position, rayDirection * 10, Color.magenta);
8.  

 

In the answer you found, the last was this:

Code (CSharp):

1.  
2. Vector3 tiltInput = new Vector3 (Input.GetAxis ("Horizontal"), 0, Input.GetAxis ("Vertical"));
3.  
4. float y = (-hit.normal.x * tiltInput.x - hit.normal.z * tiltInput.z) / hit.normal.y;
5. Vector3 rayDirection = new Vector3 (tiltInput.x, y, tiltInput.z);
6.  
7. rayDirection.Normalize ();
8. Debug.DrawRay (transform.position, rayDirection * 10, Color.magenta);
9.  

 

This one shoots along the angle of the player on some slopes instead of the angle of the slope

This one doesnt do anything at all on some slopes, the direction will stay the same no matter your rotation

 

This one does not do anything some times too


This is still the best answer

Code (CSharp):

1. Vector3 tiltInput = new Vector3(Input.GetAxis("Horizontal"), 0 , Input.GetAxis("Vertical"));
2. Vector3 projForward = transform.forward - (Vector3.Dot(transform.forward, hit.normal) * hit.normal);
3. Vector3 rayDirection = Quaternion.LookRotation(projForward, hit.normal) * tiltInput;
4. rayDirection.Normalize();
5.  
6. Debug.DrawRay(transform.position, rayDirection * 10, Color.magenta);

 

It seems you did a very deep test... I only tryed on the same slope. There was another solution after the one I posted in the answer thread (the very last): did you tested it too?

 

Yes I tried that one aswell, doesnt work.
Wonky on the x axis, gives shortened direction or starts pointing into the sky/floor
may have given the wrong z axis aswell dont remember