A message for Yombo (but also for all who can help me)

I write here because i've no way to put all into twitter :) and because i haven't your email address.

I'll talk about my issue with quaternions.

So, i've changed a lot the code, hoping that it solves my problem but nothing changes.

Now the "lookAt" function doesn't receive a vector, but two angles: pitch and yaw. First i compute the pitch rotation (Quaternion q), then the yaw rotation (Quaternion r), and last multiply the two quaternions and rotate the camera using the result.

void MyCamera::lookAt(Ogre::Real pitch, Ogre::Real yaw) {

Quaternion q(Degree(pitch), Vector3::NEGATIVE_UNIT_X);
Quaternion r(Degree(yaw), Vector3::NEGATIVE_UNIT_Y);
q=q*r;
mCamera->rotate(q);
}



This is what happens.



in the upper-left panel now i display the "right" vector of the camera. Ok?

1. First i rotate around Y axis (yaw), keeping pitch==0 all the time: you can see that right vector has his y coords always = 0. It's correct: the y component of right vector defines the "roll" rotation. If it's always 0, camera does not rolls.
2. Next i rotate around X (pitch), keeping yaw==0 al the time. Now the right vector is = (1,0,0), always. In the video you can see not properly (1,0,0) because of the Ogre::Real resolution, but it's something like (1,0.00000001,0.00000001). And it's correct; when i pitch changes the look at, changes the up vector, but the right vector remains normal to plane YZ. Again: the y component of right vector is always = 0, so no "roll" of the camera. Perfect.
3. Finally i unlock both rotation and start to combine it: the camera starts to roll, and you can see tha the y component of right vector grows... if it's > 0 camera rolls left, if it's <>

My questions now are: WHY!?!? What's wrong? And what is the correct way?

Thank you for the patience. I'm a noob about rotation.

Solution not found :(

Hi guys.
I've follow your suggestion about use quaternions to rotate my camera into the space and the upside/down problem that i had using the lookAt method of the Camera class, seems to be fixed
(here the previous video to show you)



Before i've used the spherical coordinates.. when you move the mouse in x direction i change the yaw angle, and when you move in y direction i change the pitch angle.
After modified the angles, i compute the unitary vector that represent the orientation of the camera:

   direction.x=sin(yaw)*sin(pitch);
   direction.y=cos(pitch);
   direction.z=sin(pitch)*cos(yaw);

Finally i use the "lookAt" method to orientate the camera along the "direction" Vector3.
But the side effect is that, when pitch angle go outside the interval (0,PI), the camera flips upside down.

So, i've changed the approach.. no more lookAt but quaternions.

void MyCamera::lookAt(Vector3* dir) {

  //no more used
  //mCamera->lookAt(dir->x,dir->y,dir->z);

   Vector3 src =  mCamera->getDerivedOrientation() * Vector3::NEGATIVE_UNIT_Z;      // Orientation from initial direction. Camera points to (0,0,-1)
   Quaternion quat = src.getRotationTo(*dir);
   mCamera->rotate(quat);
}

And this is the result:



i've changed the starship mesh with a more clear xyz axis mesh: x is in red, y in green and z in blue.
First i try to do a yaw rotation, around the Y axis... it works fine.
Then pitch rotation and.. well! it works! no more upside-down.
But.. when i combine both and give freedom to camera move something strange happens: moving it cause a side effect: some roll rotations starts to appears and the more i rotate clockwise my mouse, the more the roll appears... and rotating the mouse in other direction changes the roll direction too..

Why??

And how can i remove it?

Find a solution?

Pheraphs yes...
Using the quaternions.

Stay tuned :)

I need a little help.

I'm just stucked inside a small but annoying issue and i'm tired and unable to find an elegant solution.
So i'll post here my problem to see if there's someone could help me..


I'm working on orientation of our spaceship.
The ship has two vector (Vector3): the position and the orientation. The first is the position of the ship in space, the second should be a unitary vector that represent the "lookAt" orientation (in local coordinates).
If you're sitted on the cockpit, this represent the direction you're looking to.

To implement this i've used the spherical coords, so, to obtain the vector:


orientation.x=sin(fi)*sin(theta);
orientation.y=cos(theta);
orientation.z=sin(theta)*cos(fi);



where fi is the yaw angle, and theta is the pitch angle.

It works fine for yaw, but.. for pitch, when the angles become less below zero or greather than PI, the screens flips! (look at 0:17)




I think that the issue should be that when theta is outside (0,PI), sin(theta) is <0, and both x and z become negative, and in some ways it invert the up-right vectors.
You can see it into the video: on the upper-left panel there's the ship position and ship orientation (you should use 720p resolution to see the numbers)
For now i've limited the rotation from 0 to PI but it's ugly.. i'd like to pitch and yaw without restricts, i'd like to make loops with my ship without this glitch.
Any idea?

Thank you.

Spaceship adrift near the sun

I've taken a mesh from a 3ds model and tried to import it into my game.
Sorry for the glitches: i've some problem with the hard-drive drivers...

GUI - updated

A screenshot just to show you how appears the widgets: you can see a vertical slider, a checkbox, a combobox, a text field, a static text area, a button. And there are LOTS more..

GUI

It was a complicated year. My job goes well, but this kill any spare time about Tau Ceti
Anyway, after a long pause, i've restarted (again!) to work on it and i've inserted, finally, a good GUI engine.
It's the CEGUI project, that is a "free library providing windowing and widgets for graphics APIs / engines where such functionality is not natively available, or severely lacking. The library is object orientated, written in C++, and targeted at games developers who should be spending their time creating great games, not building GUI sub-systems!".
There's a visual editor and you can insert LOTS of widgets: buttons, checkbox, dropbox, text area, and so on.. i've integrated it into Tau Ceti and it works.
For now i've added a single button: "QUIT" :) but works well and is very easy to manage, and it integrates perfectly inside the 3d scene.
When i've a more complex scene, i'll show you some examples.

News are incoming...

Stay tuned...