Angle between SceneNodes

[Andreas]

Hi all,

i have some basic question i'm stuck with for hours by now. I searched the forum, but had no luck...

I just want to get the Angle between two sceneNodes so i can rotate one to face the other in a smooth way.



I found the following to face a target scene node (unitNode==SceneNode of player, target==SceneNode of target):

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void CBaseUnit::faceTarget() {
    vector3df diff = target->getPosition() - unitNode->getPosition();
    unitNode->setRotation(diff.getHorizontalAngle());
    unitNode->updateAbsolutePosition();
};

But this is setting the rotation directly. I would like to rotate the scene node with these methods, to make it look nicer:

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void CBaseUnit::turnLeft(unsigned int deltaTime) {
    matrix4 m = unitNode->getRelativeTransformation();
    matrix4 n;
      n.setRotationDegrees(vector3df(0, (-speed * rotationSpeed * deltaTime), 0));
      m *= n;
    unitNode->setRotation(m.getRotationDegrees());
}

and

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void CBaseUnit::turnRight(unsigned int deltaTime) {
    matrix4 m = unitNode->getRelativeTransformation();
    matrix4 n;
      n.setRotationDegrees(vector3df(0, (speed * rotationSpeed * deltaTime), 0));
      m *= n;
    unitNode->setRotation(m.getRotationDegrees());
}

But how do i determine the angle between the scene nodes (or even better, their positions as vector3df)? How do i know when to rotate left or right and that i still have to rotate. :-/

Any help would be great!

Thanks,
Andreas

[jontan6]

what if u just do linear interpolate on each axis?

[Masterhawk]

Do you just want to rotate in 2D(just turn left and right or even up and down?) or can the models have an arbitrary position and angle in 3D space?

[Andreas]

Hi,

thanks for your answers so far! The models can only rotate around the y-axis (it's a top down view).

I tried using:

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  vector3df s(0, startRotation.Y, 0);
  vector3df d(0, destinationRotation.Y, 0);
  unitNode->setRotation(s.getInterpolated(d, tick));

with

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startRotation = unitNode->getRotation();
destinationRotation = (destination - unitNode->getPosition()).getHorizontalAngle();

and with "tick" beeing incremented during frames (and between 0.0 and 1.0), but it doesn't work. Obviously i am not understanding the interpolation process...

Any suggestions?
Andreas

[ehenkes]

I also had to turn around the Y-axis for facing each other:

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void CCharacter::lookAt(vector3df vecEnd)
{
  static f32 yDegree;
  vector3df vecStart = getPos(); //position of looking character
  f32 yRadian = atan2( vecEnd.X - vecStart.X, vecEnd.Z - vecStart.Z );
  yDegree = f32(yRadian * RADTODEG); 
  yDegree = f32(s32(yDegree)%360); 
  if( yDegree != 0 )
  getNode()->setRotation(vector3df( -90, yDegree+90, 0 )); 
}

Hope it helps you a little bit. It is not perfect, but it works. Thus, if you find a better general solution, please post it here.