8-Way Animation Blending

Questions & Answers
1

I’ve made some run animations for a character and I’m having some difficulty implementing them. There are 8 separate animations that each correspond to a possible run direction using the WASD keys. They are forward, back, left strafe, right strafe, and the four in-between animations. Just using the four main animations(forward, back, left, right) would be easy - just set the weight to vertical and horizontal input, but I can’t seem to wrap my head around how to implement the in-between animations. I am using Input.GetAxis for the input, so the input will be smoothed.

Any advice on how to proceed with this?

2

In my game, I blend the animations (6, since I am on a hex grid) based on the angle between the look direction and the move direction, not directly via the input.

function Update () {
 lastPos = curPos;
 curPos = transform.position;
 
 if(curPos != lastPos){
 curAngle = Vector3.Angle((curPos - lastPos).normalized, transform.forward);
 clockwise = angleDir(transform.forward, (curPos - lastPos).normalized, Vector3.up);
 if(curAngle < 30)
 animation.CrossFade("walk_F", 0.1);
 else if(curAngle > 30 && curAngle < 90 && clockwise < 0) 
 animation.CrossFade("walk_FL", 0.1);
 else if(curAngle > 30 && curAngle < 90 && clockwise > 0) 
 animation.CrossFade("walk_FR", 0.1);
 else if(curAngle > 90 && curAngle < 150 && clockwise < 0) 
 animation.CrossFade("walk_BL", 0.1);
 else if(curAngle > 90 && curAngle < 150 && clockwise > 0) 
 animation.CrossFade("walk_BR", 0.1);
 else if(curAngle > 150) 
 animation.CrossFade("walk_B", 0.1);
 }
 
 if(curPos == lastPos)
 animation.CrossFade("idle", 0.1); 

function angleDir(fwd: Vector3, targetDir: Vector3, up: Vector3) {   //determines CW or CCW
 var perp: Vector3 = Vector3.Cross(fwd, targetDir);
 var dir: float = Vector3.Dot(perp, up);
 
 if (dir > 0.0) {
 return 1.0;
 } else if (dir < 0.0) {
 return -1.0;
 } else {
 return 0.0;
 }
}

There are no real blends between the animations here, since the player can only move in distinct directions, but it should be quite simple to implement…

3

What you want to do is use animation.Blend(“animname”, weight) and calculate your weight depending on what’s important for you.

For us, we had a 4 way blend and we use the heading angle to calculate the correct blend weight:

  1. get blending angle in radians
  2. calculate sine and cosine
  3. save sign of sine and cosine
  4. animation.blend(“forward”, Mathf.Clam01(cosSign * cosinevalue^2))
  5. animation.blend(“up”, Mathf.Clam01(sineSign * sinevalue^2))
  6. animation.blend(“back”, Mathf.Clam01(cosSign * cosinevalue^2 * -1))
  7. animation.blend(“down”, Mathf.Clam01(sineSign * sinevalue^2 * -1))

This will give you values between 0-1 for each animation and will let you blend between.