Proper depth buffer handling with minimal alpha support.

src/video.cpp

@@ -33,13 +33,16 @@ void Video::Setup(int width, int height)
     glShadeModel(GL_SMOOTH);
     glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
     glClearDepth(1.0);
-    glDisable(GL_DEPTH_TEST);
-    glDepthFunc(GL_LEQUAL);
-    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
 
+    glEnable(GL_DEPTH_TEST);
+    glDepthFunc(GL_LEQUAL);
+    glEnable(GL_ALPHA_TEST);
+    glAlphaFunc(GL_GEQUAL, 0.01f);
     glEnable(GL_BLEND);
     glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 
+    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
+
     /* Projection matrix: once and for all */
     glMatrixMode(GL_PROJECTION);
     glLoadIdentity();