CODEWITHSUNDEEP
vectorunity-game-engine
shaveenk
shaveenk

Reputation: 2083

Calculating actual angle between two vectors in Unity3D

Is there a way I can calculate the actual angle between two 3D Vectors in Unity? Vector3.Angle gives the shortest angle between the two vectors. I want to know the actual angle calculated in clockwise fashion.

Upvotes: 13

Views: 43997

Answers (3)

Kino Bacaltos
Kino Bacaltos

Reputation: 393

It's easy if you just use addition and subtraction. Look at this:

/Degrees
  float signedAngleBetween (Vector3 a, Vector3 b, bool clockwise) {
  float angle = Vector3.angle(a, b);

  //clockwise
  if( Mathf.Sign(angle) == -1 && clockwise )
    angle = 360 + angle;

  //counter clockwise
  else if( Mathf.Sign(angle) == 1 && !clockwise)
    angle = - angle;
  return angle;
}

Here's what i mean: if we are clockwise and the angle is negative, e.g. -170 to make it 180, you use this equation. "180-|angle|+180" you already know that the angle is negative, so, use "180-(-angle)+180" and add the 180's "360 + angle". Then if it's clockwise, CONTINUE but if it's counter clockwise, make the angle negative, this is because the other part of the 360 angle (which is the compliment of 360 + angle) is "360 - (360 + angle)" or "360 - 360 - angle" OR "(360 - 360) - angle" and, again, OR "- angle". So there we go... your finished angle.

Upvotes: 0

Jerdak
Jerdak

Reputation: 4056

This should be what you need. a and b are the vectors for which you want to calculate an angle, n would be the normal of your plane to determine what you would call "clockwise/counterclockwise"

float SignedAngleBetween(Vector3 a, Vector3 b, Vector3 n){
    // angle in [0,180]
    float angle = Vector3.Angle(a,b);
    float sign = Mathf.Sign(Vector3.Dot(n,Vector3.Cross(a,b)));

    // angle in [-179,180]
    float signed_angle = angle * sign;

    // angle in [0,360] (not used but included here for completeness)
    //float angle360 =  (signed_angle + 180) % 360;

    return signed_angle;
}

For simplicity I reuse Vector3.Angle and then calculate the sign from the magnitude of the angle between plane normal n and the cross product (perpendicular vector) of a and b.

Upvotes: 22

aaa
aaa

Reputation: 499

Try to use Vector3.Angle(targetDir, forward);

Since you want the shortest angle between them, then if the value returned is more than 180 degrees, just subtract 360 degrees with this value.

Check out http://answers.unity3d.com/questions/317648/angle-between-two-vectors.html

Upvotes: -8

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