   camera model-rotation problems...
  A wierd thing is happenging...I''m currently implementing a very basic camera model using a 3x3 matrix for camera rotaion and a 3-vector for the camera position/translation.So far I''ve only implemented three functions:cam_rot_x(),cam_rot_y(),cam_rot_z().Since I haven''t implemnted any translation I use glTranslatef() for that part.What happen is:When I use the cam_rot_y() func like this:glTranslatef(some,values,here);cam_rot_y(another_value);draw_scene();I get the exact opposite rotation(-another_value) than when I use glRotatef(another_value,.0,1.0,.0) instead of cam_rot_y.There''s no problem with rotation around the x and z axes just y.To eliminate the possibility of math functions(like matrix multiplication,etc.)beeing the problem I changed my cam_rot_y() function so it now looks like this:void cam_rot_y(float a){  float rot_mat[9]={cos(a) ,0 ,sin(a),0 ,1 ,0,    -sin(a),0 ,cos(a)},res_mat[9];  float mat[16]={ rot_mat[0],rot_mat[1],rot_mat[2],0,   rot_mat[3],rot_mat[4],rot_mat[5],0,   rot_mat[6],rot_mat[7],rot_mat[8],0,   0    ,0    ,0    ,1};  glMultMatrixf(mat);/*  mm_mult3(cam_mat,rot_mat,res_mat);  mm_copy3(res_mat,cam_mat);*/}So it just creates a rotation matrix,initially 3x3,converts to 4x4 and multiplies it by the curent martix?Isn''t that what glRotatef() does?cam_rot_x and cam_rot_z look exactly the same except for the rot_matrices and work fine.What''s the problem with this one?Any help would be greatly apreciated...  
  I just added some basic translation which the same as the glTranslatef() command so I guess the problem doesn''t lie in using glTranslatef() to cover for the lack of translataion in the camera model...So what is it???  ;  just remember that your y is negative for up. i am taking a wild stab in the dark, but possibly you are expecting the vector {0,1,0} to point up. but that is actually down. hope that helps 