Vectors are a powerful tool in programming, particularly useful in game development. They can represent directions, velocities, and obviously, positions in 3D space. When working with these vectors, we sometimes need to calculate the angle between two vectors. This where Vector3.SignedAngle method of Unity comes into action.

**Unity’s Vector3.SignedAngle** method calculates the angle in degrees between two vectors with the regard to the direction. Its value ranges from -180 to 180, thus giving us the direction as well. Unfortunately, some users have reported issues with it not displaying the signed angle correctly. Let’s delve into a viable solution to this common problem.

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## Correct Usage of Vector3.SignedAngle

It’s crucial to understand how **Vector3.SignedAngle** works to resolve the issue. This method takes three arguments, namely from, to, and axis. “From” and “to” are the two vectors we are calculating the angle between, while “Axis” is the vector around which we are measuring the angle.

Vector3 from = new Vector3(1, 0, 0);

Vector3 to = new Vector3(0, 1, 0);

Vector3 axis = new Vector3(0, 0, -1);

float angle = Vector3.SignedAngle(from, to, axis);

In the code above, it’s vital to ensure the axis is perpendicular to the plane containing the two vectors. This is because, in a 3D space, the angle could differ based on the rotation axis.

## Vector3.SignedAngle Not Showing Signed Angle – The solution

The problem arises when the vectors are in a different plane from what we expect. If axis’ direction is off, it can return positive values when it should return negative and vice versa. Here’s an alternative method to find the signed angle which works regardless of the plane your vectors reside on:

Vector3 v1 = new Vector3(1, 0, 0);

Vector3 v2 = new Vector3(0, 1, 0);

Vector3 crossProduct = Vector3.Cross(v1, v2);

float dotProduct = Vector3.Dot(v1, v2);

float signedAngle = Mathf.Atan2(crossProduct.magnitude, dotProduct) * Mathf.Rad2Deg;

if (crossProduct.z < 0) signedAngle *= -1;
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This signed angle calculation uses the **Dot** and **Cross Product** of the two vectors which provides the direction and magnitude of the angle between them, respectively. Finally, if the z component of the cross product is negative, just multiply the angle by -1 to get the negative angle.

Make sure to remember that the ‘Dot’ and ‘Cross Product’ are the fundamental concepts behind the solution. The dot product effectively gets the cosine of the angle, while the cross product obtains the sine. These operands give us a full representation of the vector in 3D space, facilitating a robust solution to getting the signed angle.

Applying these methods will smartly fix the issue of Vector3.SignedAngle not showing the signed angle in Unity, and you can proceed ahead with your game development projects. Keep in mind that understanding these fundamental vector operations will open doors to a variety of other tasks involved in 3D game development. Happy coding!