problems with enabling the polygon smooth

OpenGL OpenGL: Basic Coding
1

When i enable the polygon smooth, i see a line in my polygons :eek: What’s the problem?
-Ehsan-

2

Do you use glHint (GL_POLYGON_SMOOTH_HINT) ?

You must draw from front to behind, use blending with GL_SRC_ALPHA_SATURATE.

This is the only way I know, maybe there is something about multipasses, either I don’t know.