demos: Set the depth mask correctly to get the desired blending

progs/demos/spriteblast.c

@@ -209,13 +209,13 @@ redraw(void)
 {
   int i;
 
+  glDepthMask(GL_TRUE);
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
   glPushMatrix();
   glRotatef(15.0, 1.0, 0.0, 0.0);
   glRotatef(angle, 0.0, 1.0, 0.0);
 
-  glDepthMask(GL_FALSE);
 
   /* Draw the floor. */
 /*  glEnable(GL_TEXTURE_2D);*/
@@ -232,7 +232,7 @@ redraw(void)
   glEnd();
 
   /* Allow particles to blend with each other. */
-  glDepthMask(GL_TRUE);
+  glDepthMask(GL_FALSE);
 
   if (blend)
      glEnable(GL_BLEND);