OpenGL and GLUT uncomprehension - opengl

Question

i'm completely don't understanding opengl+glut works....
PLEASE explain why he does that? =(
I have simple code
void display()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPushMatrix();
ChessboardSurrogate.Draw(6,8,50, 0,0); // draw chessboard(6x8) in (0,0,0) edge per cell 50
glPopMatrix();
glPushMatrix();
//glutSolidCube(100); //!!!!!
glPopMatrix();
glLoadIdentity();
gluLookAt( 0.0, 0.0, -testSet::znear*2,
0.0, 0.0, 0.0,
0.0, 1.0, 0.0);
glMultMatrixf(_data->m); // my transformation matrix
glutSwapBuffers();
}
And i get the expected result. screenshot #1
Then I uncomment glutSolidCube(100). In any case, I even do push/pop current matrix, and later override it by identity matrix.... i think that i would see the same result image with cude... BUT! i see THIS screenshot #2 What the..... &*^##$% Why?
If i add code
glRotatef(angleX,1.0,0.0,0.0);
glRotatef(angleY,0.0,1.0,0.0);
before glutSwapBuffers, than I'll see that the chessboard on the spot .....
screenshot #3

Answer 1

This is probably only half the answer, but why on earth are you setting your matrices AFTER drawing ? What do you expect it to do ?
so :
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
gluLookAt( 0.0, 0.0, -testSet::znear*2,
0.0, 0.0, 0.0,
0.0, 1.0, 0.0);
glMultMatrixf(_data->m); // my transformation matrix
glPushMatrix();
ChessboardSurrogate.Draw(6,8,50, 0,0); // draw chessboard(6x8) in (0,0,0) edge per cell 50
glPopMatrix();
glPushMatrix();
//glutSolidCube(100); //!!!!!
glPopMatrix();
glutSwapBuffers();
moreover, always make sure you're setting the right matrix :
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt()...
Lastly, unless your Draw() method changes the modelview matrix, your Push/PopMatrix is useless and should be avoided (for performance and portability reasons since it's deprecated)