#### Archived

This topic is now archived and is closed to further replies.

# Quaternion

This topic is 6016 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

## Recommended Posts

Im trying to move a camera with a quaternion. Ive got the rotations down fine, 6DOF, looks great. My only problem is that I cant figure out how to move the camera based on the direction vector. It seems to move fine if I dont rotate the camera, it will move back and forth but when i rotate while moving it all goes to hell. here is some sudo code

Vector3 position;
Quaternion rotation;
Vector3 directionVector = getQuaternionDirectionVector(rotation);
position.x += directionVector.x * timeDelta * speed;
position.y += directionVector.y * timeDelta * speed;
position.z += directionVector.z * timeDelta * speed;

anyone know what Im doing wrong?

##### Share on other sites
first this is how i extrect the vied vector from the quaternion matrix

ViewDir[0]=matrix[2 ];
ViewDir[1]=matrix[6 ];
ViewDir[2]=matrix[10];

this will give you the idea of the row / column orientation ( i hope )

__forceinline void OBSERVER::Right( float speedx )
{
////////////////////////////////////////////////
// translate x
Pos[0]+=matrix[0]*speedx;
Pos[1]+=matrix[4]*speedx;
Pos[2]+=matrix[8]*speedx;
}

__forceinline void OBSERVER::Up( float speedy )
{
////////////////////////////////////////
// translate y
Pos[0]+=matrix[1]*speedy;
Pos[1]+=matrix[5]*speedy;
Pos[2]+=matrix[9]*speedy;
}

__forceinline void OBSERVER::Forward( float speedz )
{
///////////////////////////////////////
// translate z
Pos[0]+=matrix[2]*speedz;
Pos[1]+=matrix[6]*speedz;
Pos[2]+=matrix[10]*speedz;
}

if you want to reverse the direction just give a negative value to the speed factor.

byez

##### Share on other sites
I think the problem has to do with the way im rotating/translating the world. The objects seem to handle the rotating/translating just fine. But if I move the camera''s rotation but not the position it looks fine. Currently I have a CCamera which holds a Vector for the position and a Quaternion for the rotation. My world view is a CCamera and all the things I draw have CCamera''s.

So lets say I have a camera and 1 object. And I want the to see the view from inside the object.

  Quaternion objectRotation;Vector3 objectPosition;Quaternion worldRotation= objectRotation;Vector3 worldPosition = -objectPosition;Matrix4 view;view.LoadIdentity();view.Translate(worldPosition);view = worldView * worldRotation.getMatrix();glLoadIdentity();glMultMatrixf(view.m); // view.m is a float[16]glPushMatrix();view.LoadIdentity();view.Translate(objectPosition);view = objectView * objectRotation.getMatrix();glMultMatrixf(view.m); // view.m is a float[16]drawObject();glPopMatrix();

Would this be correct?

##### Share on other sites
I didn''t understand your last post, but is it possible that you need the inverse rotation quaternion? Something like:
Vector3 directionVector = getQuaternionDirectionVector(getQuaternionInverse(rotation));
Inverting a quaternion is not that hard... if you don''t know, just search in google. I would give it a try, as you often store the inverse rotation in your camera quaternion (rotate head right == rotate world left).
Or do I mix up things here?

1. 1
2. 2
Rutin
21
3. 3
A4L
15
4. 4
5. 5

• 13
• 26
• 10
• 11
• 44
• ### Forum Statistics

• Total Topics
633741
• Total Posts
3013624
×