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  Vektors and Angles  (Read 3063 times)
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Offline Bananni

Senior Newbie

Belive the hype!

« Posted 2010-09-10 20:57:32 »

i got a problem for calculating my camera.
I tried so much stuff.
What i got:
2 Vektors:
  p = my aktual position
  t = my desired point
My wished point to look @ is in the center of my coor-system.
Now i have done the calculation of u( = the vektor where the cam is moving ).
In the next step i want to use t to get the angles to my wished point w(0,0,0); t+w = my view direction.
I've done a small graphic for this:

I tried to get the angles on this way:
First i turned the direction of t around, so all values are multiplied by -1.
Now my Vektor t is pointing down to w(0,0,0).
In the next step i reduced t on 2 Planes.
So i can calculate the angles with X/Y and X/Z
a = arccos(  (tx,ty)skalar(1,0) / |(tx,ty)|*|(1,0)|);
b = arccos(  (tx,tz)skalar(0,1) / |(tx,tz)|*|(0,1)|);

But my result is bad  Sad

(thats math so it have to be in this forum, right? if not, it may belongs to JOGL, im sry)

Offline Riven
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« JGO Overlord »

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Hand over your head.

« Reply #1 - Posted 2010-09-10 21:23:20 »

If I understand your problem correctly, you want to move
   from position of end of vector P
   to position of end of vector T
   through vector u
   looking at 0,0,0

If this is correct, you can simply lerp between the points, and at every intermediate position, calculate the angles to 0,0,0, using:

// Y axis is UP

   public static double yawAngle(Vec3 a, Vec3 b)
      return atan2(b.z - a.z, b.x - a.x);

   public static double pitchAngle(Vec3 a, Vec3 b)
      return atan2(b.y - a.y, distanceXZ(a, b));

   public static double distanceXZ(Vec3 a, Vec3 b)
      float x = a.x - b.x;
      float z = a.z - b.z;

      return Math.sqrt(x * x + z * z);

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Offline Bananni

Senior Newbie

Belive the hype!

« Reply #2 - Posted 2010-09-10 21:38:07 »

nice, thx.
that was what i was looking for :3

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