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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(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 ...
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2answers
617 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 * ...
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1answer
319 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 ...
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2answers
396 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 ...
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2answers
296 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, ...
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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 ...
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3answers
304 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)); ...
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2answers
961 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: ...
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1answer
405 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 ...
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337 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 = ...
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3answers
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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?
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1answer
893 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 ...
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1answer
254 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 ...
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1answer
277 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 ...
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2answers
2k 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 ...
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5answers
2k 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 ...
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0answers
361 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
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1answer
696 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 * ...
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2answers
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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 ...
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1answer
1k 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 ...
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1answer
570 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 ...
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2answers
1k 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 ...
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1answer
405 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 ...
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2answers
1k 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 ...
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1answer
2k 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 ...
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2answers
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How do I correctly use dual quaternions for rotation and translation of an object?

Up until now I've handled a given object's rotation and translation separately using normal quaternions for rotation and vectors for translation. However I'd like to use dual quaternions to handle ...
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2answers
890 views

Why is my quaternion camera rotating around strange axes?

I can't get it to work for the life of me. Its rotating the camera in the global coordinate system, or some other random coordinate system, not the camera local coordinate system. WASDEC work ...
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2answers
503 views

How do I extract a translation vector from a dual quaternion?

I'm trying to do some things with rigid body dynamics using dual quaternions (these are not the same thing as normal quaternions!) and I'm so close to getting things to work. The problem I'm having is ...
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2answers
473 views

How can I orient a projectile along its flight path?

I have a projectile that is moving around the world (in a ballistics trajectory right now). I am currently keeping track of its position and velocity. I want to draw it oriented to its velocity, so ...
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3answers
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How do I implement a quaternion based camera?

UPDATE The error here was a pretty simple one. I have missed a radian to degrees conversion. No need to read the whole thing if you have some other problem. I looked at several tutorials about this ...
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2answers
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How can I rotate about an arbitrary point in 3D (instead of the origin)?

I have some models that I want to rotate using quaternions in the normal manner, except instead of rotation about the origin, I want it to be offset slightly. I know that you don't say, in 3d space, ...
2
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3answers
456 views

How should I model exact 90-degree rotations in 3D?

I'm familiar with quaternions... have used them in the past to model arbitrary rotations in 3D, as for a plane flying around with full pitch/yaw/roll freedom. Works great. Now I'm working on a 3D ...
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2answers
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How can I rotate a sphere in response to mouse movement?

I'm using jMonkeyEngine to develop a game. I'm good at scripting, but math usually goes over my head. I tried the Wiki page for Quaternion, but I was far too confused to figure this out myself :P My ...
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3answers
473 views

Create quaternion based on where a unit is hit (shield effect as in Starcraft 2) [duplicate]

I'd like to implement a shield effect like that done for Protoss units in Starcraft 2. I'm guessing that the technique involved uses a partial sphere that is rotated to reflect where a unit is hit. ...
4
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3answers
684 views

Problem representing torque as a quaternion

Euler angles are much more intuitive to me than quaternions for representing 3-dimensional rotations. In fact, I barely understand quaternions at all. I use quaternions for rotation because people ...
3
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2answers
628 views

Quaternion understanding

I have some understanding problem concerning quaternions. In order to have my world object rotate in the correct way, I need to invert their quaternion rotation while refreshing the object world ...
11
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1answer
2k views

Quaternions and rotation around world axis

Disclaimer: I am a professional games programmer, and use quaternions most days but they are close to black magic to me. I am relatively at home with math but imaginary numbers always confused me. I ...
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2answers
491 views

OpenGL Camera causes spatial distortion

I'm trying to implement a 3D camera of the "Orbit around the origin" variety in a game engine I'm developing in order to learn about 3D graphics and game programming. I have a basic handle on the ...
17
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1answer
7k views

Orienting a model to face a target

I have two objects (target and player), both have Position (Vector3) and Rotation (Quaternion). I want the target to rotate and be facing right at the player. The target, when it shoots something ...
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2answers
2k views

GLM: Quaternion SLERP Interpolation

I wish to interpolate two quaternion values. As I still can not get working results, can I kindly ask you to verify my function calls? The code below supports GLM (OpenGL Mathemathics) library, so ...
11
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1answer
861 views

Moving an Object along a Curve while Rotating it

I woud like to move an object along a curve. At particular points on the curve, I wish the object to change speed and rotate itself along its axis. Imagine an airplane flying to a destination. It has ...
12
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6answers
4k views

Math topics for 3D graphics programming

I understand that the following math topics are required for 3D graphics programming. I have started doing some of them in my math course. Can someone point me in the direction of a resource that ...
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5answers
4k views

How can you visualize a quaternion?

When I visualise a three dimensional rotation matrix, or scaling matrix I visualize it as three axes. Is there a similar way that I can visualize a rotation quaternion?