For each triangle in my mesh i do the dot product of -normal of the triangle and camera vector(in the shader).
I do this because when the result of the dot product inform me of the front/back face related to the camera.
If the result of the dot product for example is 0 mean that the normal is perpendicular of my camera vector, then i must change to drawing from front face(for example red)and start to drawing back face(for example yellow if the two face colors are red and yellow).
My problem is this:
when the faces or triangles are far away all work fine, but when the faces are near the camera the change of back/front face is incorrect, i think that this may be relative to the projection matrix, but if this is true , how i can correct?
I can multiply the camera vector for the projection matrix?