Mathematical constructions, number systems. In 3D-graphics quaternions are used alongside vectors and matrices. One of the benefits of quaternions is that they overcome some rotational problems (known as gimbal locks) that are inherent to vectors and matrices.
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0answers
37 views
How to set object's / node's absolute rotation correctly?
Usually when I want to rotate an object/node in my Ogre scene I call the node's rotate() method. That rotates the node locally relative to it's current rotation. So for example, when I start with 0 ...
3
votes
1answer
47 views
How to map absolute Joystick position to object rotation?
In my (Ogre) 3d scene I have an object that should be rotated locally based on Joystick input. I have a Joystick with min/max values of [-32767, 32767] on both X and Y axes. When the Joystick is in ...
2
votes
1answer
43 views
Rotating and Translating a Node in Horde3D with Matrices and Quaternions
I have been trying to learn how to use the Horde3D rendering engine for the past couple of days,
and so far I have managed to learn a decent amount and integrate Bullet Physics with it as well.
My ...
3
votes
1answer
89 views
What is the rationale behind this method of computing the w-component from MD5 mesh files?
In tutorials regarding the MD5Mesh format, like this one, we often see code like
float t = 1.0f - (q.x * q.x) - (q.y * q.y) - (q.z * q.z);
if (t < 0.0f) {
q.w = 0.0f;
} else {
q.w = -sqrt ...
0
votes
1answer
57 views
Mouse Aiming Causing Rotation Jitter
When our game's ships move around, mouse aiming causes them to shake around a lot. The body being aimed is moved kinematically. I think we've narrowed it down to this block of mouse tracking code.
...
0
votes
0answers
59 views
creating arcball in cocos 3d [closed]
I am trying to make arc ball sample in cocos 3d , the code seems to be ok, but the rotation of ball is not as expected
it seems that i've done something stupid, but i can't figure it out. please check ...
0
votes
0answers
45 views
Understanding quaternions and axis angle representations [closed]
I have a sensor that gives me a quaternion. I convert the quaternion to an axis-angle representation using http://www.euclideanspace.com/maths/geometry/rotations/conversions/quaternionToAngle/. When I ...
3
votes
1answer
143 views
Quaternion Look At with Up vector
I have implemented a "look at" method for my screen elements and it almost works how I want it to work.
The ScreenElement class uses a R3 Vector and a Quaternion to determine the position and ...
4
votes
1answer
278 views
Why game engines usually don't offer a vector3.rotate method? [closed]
Game engines like Three.js, Ogre3d and Unity3d often don't provide a default rotate method on their vector class. You usually have to do something like:
rotated = vector.applyQuaternion(
new ...
1
vote
2answers
107 views
Accumulating rotations for camera
It seems there are three ways to store a camera's rotation: in angles, view matrix or quaternion. I was using euler angles since when I used a matrix it had a tendency to accumulate rounding errors ...
1
vote
1answer
80 views
Moving an object toward another object on sphere knowing their quaternions
I have a sphere centered in world origin. On the sphere surface I have two objects and I know their quaternions (rotation around sphere).
Currently my movement works on Vector2 inputs (cannot change ...
3
votes
2answers
104 views
Calculating transform of arrow model pointing at some point in 3D space
I'm working on a 3D flight game and I'd like to implement a simple "navigation arrow" pointing at the next waypoint in world which the player has to fly to.
I have position of both airplane (=camera) ...
4
votes
1answer
71 views
Quaternion handedness issue
At least I think it is. I have the following functions:
kmQuaternionRotationAxis - Constructs a Quaternion from an axis and angle
kmMat4RotationQuaternion - Constructs a 4x4 matrix from a quaternion
...
0
votes
4answers
152 views
How much to modify yaw? XNA 4.0 [duplicate]
Heres a picture that explains better than my words can
For rotating an object I'm using quaternions.
CreateFromAxisAngle(vector3.Right,yaw)
Maybe this isn't how I should be doing it but I also ...
0
votes
1answer
504 views
Rotating Objects in OpenGL: glRotate or Quaternions?
I'm coding my first engine and I'm trying to have performance in mind since I'll probably use it for mobiles, and I have this question, should you use glRotate or Quaternions for rotating objects in ...
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votes
1answer
173 views
How can I create a WebGL camera based on quaternions?
I am trying to create a WebGL camera based on quaternions. I looked at many tutorials, and none is as simple as it could be or it was not working. How can I create such a camera?
4
votes
2answers
272 views
Matrix interpolation for animation blending
I use the XNA Animation Component library to perform blending between animations. It uses spherical linear interpolation between matrices.
In most cases this works without problems. However, I have ...
1
vote
2answers
243 views
Quaternion Camera
Can someone help me figure out how to use a Quaternion with the PerspectiveCamera in libGDX or in general? I am trying to rotate my camera around a sphere that is being drawn at (0,0,0). I am not sure ...
1
vote
1answer
145 views
Using Quaternion in libGDX
Can someone give me an explanation about how to use the Quaternion class in libGDX to move my camera around a sphere or just set it up, manipulate it, and apply it general? I am trying to acheive ...
7
votes
3answers
410 views
Routes on a sphere surface - Find geodesic?
I'm working with some friends on a browser based game where people can move on a 2D map. It's been almost 7 years and still people play this game so we are thinking of a way to give them something ...
1
vote
1answer
185 views
How to get a point to the left/right of a vector
I have a position vector of a point in space and a quaternion for it's rotation. What i'm trying to calculate is a point too the left and a point to the right.
I have the position and ...
8
votes
2answers
553 views
Arbitrary Rotation about a Sphere
I'm coding a mechanic which allows a user to move around the surface of a sphere. The position on the sphere is currently stored as theta and phi, where theta is the angle between the z-axis and the ...
2
votes
2answers
367 views
Quaternion based rotation and pivot position
I can't figure out how to perform matrix rotation using Quaternion while taking into account pivot position in OpenGL.What I am currently getting is rotation of the object around some point in the ...
3
votes
1answer
336 views
Convert rotation from Right handed System to left handed
I have Euler angles from a right handed system that I am trying to convert to a left handed system. All the information that I have read online says that to convert it simply multiply the axis and ...
2
votes
2answers
231 views
Rotating a child shape relative to its parent's orientation
When rotating a shape using a quaternion value I also wish rotate its child shape.
The parent and child shapes both start with different orientations but their relative orientations should always be ...
0
votes
1answer
234 views
(Quaternion based) Trouble moving foward based on model rotation
Using quaternions, I'm having trouble moving my model in its facing direction. Currently the model moves can move in all cardinal directions with no problems. The problem comes when I rotate the move ...
2
votes
2answers
382 views
Rotate model using quaternion
Currently I have this to rotate my 3D model that rotates on it's local axis independent from the world's axis:
// Rotate model with Right Thumbstick
modelRotation -= pController.ThumbSticks.Right.X * ...
3
votes
1answer
197 views
D3DXMatrixDecompose gives different quaternion than D3DXQuaternionRotationMatrix
In trying to solve this problem, I tracked down the problem to the conversion of the rotation matrix to quaternion. In particular, consider the following matrix:
-0.02099178 0.9997436 -0.008475631 0
...
3
votes
2answers
295 views
How to derive euler angles from matrix or quaternion?
Currently working on steering behavior for my AI and just hit a little mathematical bump.
I'm in the process of writing an align function, which basically tries to match the agent's orientation with ...
3
votes
2answers
205 views
Rotating voxels in 3d space amongst the x axis
I have a very simple voxel engine and so far it works based on coordinates, e.g. x, y, z. I was wondering if there is a formula for rotating groups of voxels/coordinates from the x axis(e.g. [0, 1, ...
1
vote
2answers
998 views
Rotation matrix derived from quaternion is opposite of expected direction
When I calculate a rotation matrix from a quaternion, it seems to be in the opposite direction. For instance:
For a rotation of +45 degrees about the Y-axis, I would expect to get the following ...
1
vote
3answers
217 views
Inverting matrix then decomposing gives different quaternion than decomposing then inverting the quat
I'm getting different signs when I convert a matrix to quaternion and invert that, versus when I invert a matrix and then get the quaternion from it:
Quaternion a = Quaternion.Invert(getRotation(m));
...
2
votes
2answers
386 views
Quaternions - how to limit axis?
Is there any possibility to limit quaternions to move only in x & y axis (like in Eulers- yaw and pitch, without rolling)? I's there any equation or something similar to do this?
Some example:
...
2
votes
1answer
299 views
Finding a suitable axis-angle to avoid gimbal lock
In OpenGL the camera faces the -z axis with the +y axis pointing up. I am using quaternions to represent the orientation of my objects (which works well) and am trying to do the same for the camera. I ...
0
votes
1answer
258 views
Rotation matrices from Quaternion.Identity and -Quaternion.Identity are the same?
If I create a rotation matrix from an identity quaternion then it is the same as a creating it from a negative identity quaternion
Matrix m0 = ...
3
votes
3answers
787 views
How to keep my Quaternion-using FPS camera from tilting and messing up?
I am using an FPS-like camera, and it uses quaternions. But, whenever I try looking up and then sideways, it tilts, and sometimes it can turn upside down. How can I fix this?
2
votes
1answer
636 views
Quaternion Camera Orbiting around a Sphere
Background: I'm trying to create a game where the camera is always rotating around a single sphere. I'm using the DirectX D3DX math functions in C++ on Windows.
The Problem: I cannot get both the ...
1
vote
0answers
164 views
Smooth Camera Offsets
I am attempting to implement a sort of, smooth camera that has angle offsets from the player as they turn, creating a cinematic effect as well as visual feedback for when the player turns.
Here is an ...
0
votes
1answer
215 views
Quaternion to axis-angle, or ripping apart a full transform matrix
My game entities currently hold a quaternion for their orientation with the ability to return either a 3X3 full rotation matrix (based on that quaternion), or a full 4X4 transform matrix. though what ...
2
votes
2answers
1k views
Quaternion rotation
I have a problem understanding quaternions rotation in OpenGL.
So far I have implemented all function and operators related to quaternions.They are definitely working right!.
However I can't find ...
4
votes
5answers
1k views
Rotating vector3 by a quaternion
I am attempting to rotate a vector3 by a given quaternion.
I know that this is true
v' = q * v * (q^-1)
I know that q^(-1) is the inverse which just -q/magnitude(q), but how do I map the ...
3
votes
0answers
287 views
Setting Orientation of Character in Bullet/Ogre [closed]
I've been suffering from an issue regarding the implementation of orienting characters in a game I'm implementing using Ogre3D and Bullet physics.
What I have: A Direction Vector that the character ...
2
votes
1answer
496 views
Rotating a vector by a quaternion
I am trying to rotate a direction vector (0,0,1,0) by a rotation quaternion in DirectX.
From what understanding, to rotate the vector you must do
NewVector = rotQuaternion * Vector * ...
7
votes
2answers
844 views
Calculating a quaternion so a bone points in a specified direction
In an attempt to solve this question, I decided to figure out the absolute (world space) directions of each joint in the source pose (as normalized unit vectors), and then rotate the joints of the ...
2
votes
1answer
693 views
Flip rotation matrix
I'm doing character control with kinect. I need to mirror the joint orientation because the character faces the player. Somehow by Googling through internet I've done it and everything works very ...
4
votes
1answer
421 views
Arcball Problems with UDK
I'm trying to re-create an arcball example from a Nehe, where an object can be rotated in a more realistic way while floating in the air (in my game the object is attached to the player at a distance ...
10
votes
2answers
915 views
Why do people use quaternions?
I have been using them as a black box for a while, I'm just learning about of the maths but I'd just like some definitive answers to this question.
So far the only benefit I've come across personally ...
0
votes
1answer
327 views
Rotate an existing quaternion around an axis?
I have an existing quaternion (Java Quat4f). I would like to rotate this quaternion around an axis (i.e. 90 degrees around the x axis, 25 degrees around the y axis, 10 degrees around the z axis, 180 ...
0
votes
2answers
711 views
from normal to rotation matrix
(i'm on OPENGL)
i have a mesh O (object) and a mesh T (terrain).
i know a single triangle in T and i want to orient O to be aligned to that triangle (torate O to align to T in that point).
i have ...
1
vote
1answer
1k views
how to create a Quaternion from an Orientation Vector in xna
i have a Vector3 represents an Orientation in 3D , how to convert it to the corresponding Quaternion ?
is there any quick way ?
EDIT :
i want to add an angular velocity vector to the Orientation ...
