OpenGL smoothing?

Question

What is this white spot? It's appeared when i add to my code this:

glEnable(GL_BLEND); //Прозрачность
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); 
glShadeModel(GL_SMOOTH); 

glHint(GL_POLYGON_SMOOTH_HINT, GL_FASTEST); 
glEnable(GL_POLYGON_SMOOTH);

glDisable( GL_DEPTH_TEST ); 
glEnable( GL_ALPHA_TEST );

How can i liquidate this? But i need smoothing... Im using for columns

gluCylinder(quadric, column_width, 0, 1, 50, 50);

Answer 1

I'm pretty sure this is because the polygons behinds are displayed. Try glEnable( GL_DEPTH_TEST ) instead of glDisable( GL_DEPTH_TEST ).