-void gis_opengl_center_position(GisOpenGL *gis, gdouble lat, gdouble lon, gdouble elev);
+void gis_opengl_center_position(GisOpenGL *opengl,
+ gdouble lat, gdouble lon, gdouble elev);
+
+void gis_opengl_project(GisOpenGL *opengl,
+ gdouble lat, gdouble lon, gdouble elev,
+ gdouble *px, gdouble *py, gdouble *pz);
+
+void gis_opengl_render_tile(GisOpenGL *opengl, GisTile *tile);
+
+void gis_opengl_render_tiles(GisOpenGL *opengl, GisTile *root);
+
+void gis_opengl_set_height_func(GisOpenGL *self, GisTile *tile,
+ RoamHeightFunc height_func, gpointer user_data, gboolean update);
+
+void gis_opengl_clear_height_func(GisOpenGL *self);