Tagged Questions

3
votes
1answer
149 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 ...
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
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 ...
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 ...
2
votes
2answers
235 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 ...
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
296 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
3answers
218 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)); ...
0
votes
1answer
259 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 = ...
10
votes
2answers
918 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 ...
1
vote
2answers
416 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 ...
9
votes
2answers
2k views

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, ...
1
vote
2answers
1k views

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 ...
1
vote
2answers
406 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 ...
1
vote
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
votes
1answer
721 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 ...
11
votes
6answers
3k 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 ...
16
votes
5answers
2k 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?