Bugfix #3579

Saving envmap, with a filter set (like gauss) and with a percentage set
(like 50%), saved envmaps with empty pixels inbetween the sub images.

source/blender/src/writeimage.c

@@ -100,8 +100,9 @@ void BIF_save_envmap(EnvMap *env, char *str)
 	int dx;
 	
 	/* all interactive stuff is handled in buttons.c */
-	
-	dx= (env->cuberes * R.r.size) / 100;
+	if(env->cube[0]->ibuf==NULL) return;
+		
+	dx= env->cube[0]->ibuf->x;
 	ibuf= IMB_allocImBuf(3*dx, 2*dx, 24, IB_rect, 0);
 	
 	IMB_rectop(ibuf, env->cube[0]->ibuf,