Perspective Matrix not working properly

Game Mechanics
#1

So Heres my Problem:

I have an Object at the center(0,0,0) with an radius of 0.1(its a sphere).

As the camera matrix and the model matrix I pass the identity matrix to the shader.
The projection matrix is an perspective matrix with an fov of 70 , an aspectratio of 16/9 and 0.1 as near clipping plane and 1000 as far clipping plane.

so the camera is at the center too, but i can see the whole object from the outside and if i pass a rotation matrix as the camera matrix, the camera rotates around the object. ???

So why is this so, any ideas where to look for an error.

ps:

the projection matrix computed with the const from above

0.80333 0 0 0
0 1.42815 0 0
0 0 1.0002 0.20002
0 0 1 1

#2

Hi,

perspective projections use 0.0 as ‘w’ component in the last matrix column.

If you use the same perspective transformation that OpenGL/GLU expects (i.e. inverting the Z axis) and using your parameters, you will end up with this matrix:

  8.0333E-1  0.0000E+0  0.0000E+0  0.0000E+0
  0.0000E+0  1.4281E+0  0.0000E+0  0.0000E+0
  0.0000E+0  0.0000E+0 -1.0002E+0 -2.0002E-1
  0.0000E+0  0.0000E+0 -1.0000E+0  0.0000E+0

Have a look at this wonderful site: http://www.songho.ca/opengl/gl_projectionmatrix.html#perspective

Also, if you like, you can have a look at JOML, which can compute all sorts of common transformation matrices and quaternions for you to be readily used with LWJGL (for example).

#3

Thanks, now it works(and it looks better)

im programming all the math things myself to understand them better.
but I will take a look at it.