I am Using the Android OpenGL. I would like to Know what append when the CenterY of the LokkAT function is changed.

It look like there is a rotation around the Eyes position. And when i change The EyeY the rotation is around the Center point difine in the Look At.

Thanks for the answer. I need Clarification for the LookAt function. ]]>

I was suprised to see that when a changed the Center-Y value of the LookAt. The world was rotating around the axis of the camera position. During using EyeY the world is rotating around the LookAt center position. So when i move CenterY and EyeY, of the lokkAt. I still need to use the same EyeZ position.

Example. EyeZ = 1.5 if i move EyeY to 1.5 i do not need to change EyeZ even if the the Ray lentgh as changed. If Know i move CenterY down to 1.5. World is running around camera Axe. But the camera position do not change, it is only the axe of view who change.

But i am surprised to see that the length of the Ray do not take in account the move of CenterY as center point of the world. The Ray is always the result of the centerY at 0.

So my picking fonction does not know how to calculate the rigth position of the world and the rigth distance to the center at CenterY

Example : EyeZ = 1.5 CenterY = 1.5

1) the Center LookAt position [x,y] should be [Cos(45°)*EyeZ,Sin(45°)*EyeZ] and the Camera position do not change position.

The world rotate around Camera EyeZ. The ray length stay 1.5 = Sqrt(X²+y²)

2) I change EyeY to = 1.5. The ray calculation is sqrt(EseY²+EyeZ²) = 2,121320344

So the new Ray length should be sqrt( (Cos(45°)*EyeZ)^2 + (EyeZ + Sin(45°)*EyeZ)²)

= sqrt( (1,060660172*EyeZ)² + ((1.5+1,060660172)*EyeZ)²) = 2,771638598

So i am wondering why Changing CenterY do not impact Ray length calculation. I look like modifing booth EyeY and CenterY does not work correctly. Let said i did not anderstoud how to mix booth. I can Use them separatly but not together except if EyeY-CenterY = 0. When this if different it is the mess.

I think i may have forget to do something. So could you help me to know how to use EyeY and CenterY correctly.

Regards Hterrolle ]]>