How to rotate a 3d game object around its center point in unity 3d.
Just use bounds.center from the renderer
Vector3 position = myGameObject.GetComponent<Renderer>().bounds.center;
myGameObject.transform.RotateAround(position, rotationVector, degreesPerSecond * Time.deltaTime);
where rotationVector is your rotation axis (Vector3)
The two common ways to rotate an object are
The rotate attribute in the transform. Using this one you can set the exact coordinates for the target object rotation. However, you'll have to manage the smoothness by yourself if you want to make animations and the values are given through Quaternion type. I recommend to use the static method Quaternion.Euler so you can pass values in a X, Y, Z. The example below set the object to turn 90 degrees clockwise in the Y axis:
transform.rotation = Quaternion.Euler (0, 90, 0);
The second approach uses the Rotation method in the same transform attribute. This method allow you to pass the amount of degrees in which object will rotate and already accept X, Y and Z coordinates instead Quaternion.
The example below rotate the object 1 degree clockwise in the Y axis:
transform.Rotate (0, 1, 0);
To best understand the difference between both methods, if you use the first one in an Update method you'll see the object static rotated 90 degrees in the Y axis. The second example used in an Update will make the object spin clockwise in the Y axis (too fast).
use
Transform.rotation
look here for Examples/Documentation :
Unity Script Reference
Related
I have written a script in Unity which takes a SkinnedMeshRenderer and AnimationClip and rotates the vertices in each by a specified number of degrees. It looks mostly correct except that rotations seem to be incorrect. Here is an example bone rotation (in euler angles) in the skeleton along with the correct values that would be needed for the animation to look correct.
With no rotation: (0, 0, -10)
Rotated 90 degrees: (-10, 0, 0)
Rotate 180 degrees: (0, 0, 10)
I have been trying to find a way to rotate these bones to make this conversion make sense with the data I have here, but have come up short. I know I want to rotate these values around the Y axis, but don't actually want the Y value in the euler angle to change. I am aware I could just reorient the root bone around the Y axis and the problem would be solved, but I want to have no rotation in the Y axis. I am "fixing" some older animations that have unnecessary rotation values in them.
var localBoneRotation = new Quaternion(keysX[j].value, keysY[j].value, keysZ[j].value, keysW[j].value).eulerAngles;
var reorientedForward = Quaternion.AngleAxis(rotation, Vector3.up) * Vector3.forward;
localBoneRotation.x *= reorientedForward.x;
localBoneRotation.y *= reorientedForward.y;
localBoneRotation.z *= reorientedForward.z;
var finalRotation = Quaternion.Euler(localBoneRotation);
keysX[j].value = finalRotation.x;
keysY[j].value = finalRotation.y;
keysZ[j].value = finalRotation.z;
keysW[j].value = finalRotation.w;
I have also tried using a matrix and Vector3 but most of the time I end up with values in the Y. Perhaps I am going about this incorrectly. I just need to be able to specify an angle rotation and then have the input data match the final euler angles with each of these data points.
For example, I have a Vector3 and I waant to rotate it relatively Y-axis (Vector3.up). Can I do it using built-in methods, or should I use coordinate geometry and trigonometry?
You can use Quaternions to rotate vectors.
For example, to rotate a source vector by 30 degrees the way you want, you can use AngleAxis() :
Vector3 v = Quaternion.AngleAxis(-30, Vector3.up) * sourceVect;
Conceptually a quaternion can store the rotation around an axis by some degree.
Now, what is the numerically most robust and least calculation intensive way to rotate the axis?
For example when i have a quaternion, which rotates 90 degrees around the y-axis and i want those 90 degrees to be applied to some other arbitrary axis, described by a normalized vector.
EDIT: Since this also came up i added an answer on how to correctly change the axis a quaternion rotates around with another quaternion.
It is a bit unclear what your actual goal is by doing what you describe.
In order to actually keep the angle but change the axis you would use Quaternion.ToAngleAxis, alter the axis and then pass it back into Quaternion.AngleAxis
like e.g.
Quaternion someRotation;
someRotation.ToAngleAxis(out var angle, out var axis);
var newAxis = Vector3.up;
var newRotation = Quaternion.AngleAxis(angle, new axis);
Or you rotate an existing Quaternion by another one using * like
Quaternion newRotation = someRotation * Quaternion.Euler(90, 0, 0);
which would take the existing rotation and rotate it by 90° around the X axis.
#derHugo's solution, solves the problem i initially asked, but the seconds part of his answer isn't doing what he seemed to be describing. To rotate a quaternions axis of rotation with another quaternion you would need to apply the rotations differently.
E.g. you have a quaternion yQuaternion, which rotates 90° around the y-axis and want to rotate, it's rotation axis by 90° around the x-axis (which would result in a quaternion rotating 90° around the z-axis) you'd have to do the following.
// The quaternion, we want to "rotate"
var yQuaternion = Quaternion.Euler(0f, 90f, 0f);
// The quaternion we want to rotate by.
var xQuaternion = Quaternion.Euler(90f, 0f, 0f);
var result = xQuaternion * yRotation * Quaternion.Inverse(xQuaternion);
What happens here is that we first rotate backwards to our desired axis, then apply the rotation we want to use and then revert the rotation we initally applied.
NOTE: I'm quit sure, that saying "rotate a quaternion" isn't a valid term when talking about this quaternion operations.
I have a main camera that rotates around an object (which I already move with AddForce). Using AddTorque, I would like the object to rotate its Y axis of rotation in the direction in which the camera's Y axis of rotation points so as to simulate the rotation of a person turning around. To do this I thought of using a force that gave me 0 when the Y axes of the two objects are the same, but I tried and the rigidbody covers only one part of the rotation of the camera while the other part is as if it not is detected.
var currentR = rb.rotation.y;
var targetR = Camera.main.transform.rotation.y;
rb.AddTorque(transform.up * 1000f * (targetR - currentR));
rotation my object
desired rotation
Vector3 camForward = Camera.main.transform.forward;
Vector3 rbForward = rb.transform.forward;
Vector3 torque = Vector3.Cross(camForward, rbForward);
rb.AddTorque(torque);
I have a transform which is being rotated around the X axis. But while transferring this rotation to another transform, i want it to do the exact same rotation. But then around the Z axis.
However, this rotation is not a "rotation" it is just a transform which rotation gets edited from the outside. So i have to rotate the original transform to match the 2nd transform, but take the rotation into account.
Axis in below images: RED = X, GREEN = Y, BLUE = Z
Rotation original:
Rotation it should have after:
What would be the correct way to go about this frame by frame?
Thanks in advance,
Smiley
I can give you an answer that solves the general problem of changing the rotation from one axis to another.
Each transform object has a transform.localRotation property that represents the orientation of the transform, relative to the parent's orientation. If the transform has no parent, than this orientation is relative to World Space.
Quaternion is the data type used to represent rotations, and it has a useful method called ToAngleAxis.
float angle;
Vector3 axis;
transform.localRotation.ToAngleAxis(out angle, out axis);
Will set the variables angle and axis to the angle and axis of localRotation. The out part means that you're passing in a variable meant to be set by the function, rather than to be used as input.
In this case, the angle variable is the part you want to actually use. If you use Quaternion.AngleAxis, providing this angle value and your desired axis, you'll get a new rotation that will match your desired parameters.
For example: To change any rotation of transform1 to a Z-axis rotation on transform2, you would use
float angle;
float axis;
transform1.localRotation.ToAngleAxis(out angle, out axis);
transform2.localRotation = Quaternion.AngleAxis(angle, Vector3.forward);
Hope this helps