How to use the bluesky.ui.qtgl.glhelpers.update_buffer function in bluesky

def actnodedataChanged(self, nodeid, nodedata, changed_elems):
        ''' Update buffers when a different node is selected, or when
            the data of the current node is updated. '''
        self.makeCurrent()

        # Shape data change
        if 'SHAPE' in changed_elems:
            if nodedata.polys:
                contours, fills, colors = zip(*nodedata.polys.values())
                # Create contour buffer with color
                buf = np.concatenate(contours)
                update_buffer(self.allpolysbuf, buf)
                buf = np.concatenate(colors)
                update_buffer(self.allpolysclrbuf, buf)
                self.allpolys.set_vertex_count(len(buf) // 2)

                # Create fill buffer
                buf = np.concatenate(fills)
                update_buffer(self.allpfillbuf, buf)
                self.allpfill.set_vertex_count(len(buf) // 2)
            else:
                self.allpolys.set_vertex_count(0)
                self.allpfill.set_vertex_count(0)

        # Trail data change
        if 'TRAILS' in changed_elems:
            if len(nodedata.traillat0):
                update_buffer(self.trailbuf, np.array(

self.route_acid = data.acid
        if data.acid != "" and len(data.wplat) > 0:
            nsegments = len(data.wplat)
            data.iactwp = min(max(0, data.iactwp), nsegments - 1)
            self.routelbl.n_instances = nsegments
            self.route.set_vertex_count(2 * nsegments)
            routedata = np.empty(4 * nsegments, dtype=np.float32)
            routedata[0:4] = [data.aclat, data.aclon,
                              data.wplat[data.iactwp], data.wplon[data.iactwp]]

            routedata[4::4] = data.wplat[:-1]
            routedata[5::4] = data.wplon[:-1]
            routedata[6::4] = data.wplat[1:]
            routedata[7::4] = data.wplon[1:]

            update_buffer(self.routebuf, routedata)
            update_buffer(self.routewplatbuf, np.array(data.wplat, dtype=np.float32))
            update_buffer(self.routewplonbuf, np.array(data.wplon, dtype=np.float32))
            wpname = ''
            for wp, alt, spd in zip(data.wpname, data.wpalt, data.wpspd):
                if alt < 0. and spd < 0.:
                    txt = wp[:12].ljust(24) # No second line
                else:
                    txt = wp[:12].ljust(12) # Two lines
                    if alt < 0:
                        txt += "-----/"
                    elif alt > actdata.translvl:
                        FL = int(round((alt / (100. * ft))))
                        txt += "FL%03d/" % FL
                    else:
                        txt += "%05d/" % int(round(alt / ft))

data.vs  = data.vs[idx]
        self.naircraft = len(data.lat)
        actdata.translvl = data.translvl
        self.asas_vmin = data.vmin
        self.asas_vmax = data.vmax
        if self.naircraft == 0:
            self.cpalines.set_vertex_count(0)
        else:
            # Update data in GPU buffers
            update_buffer(self.aclatbuf, np.array(data.lat[:MAX_NAIRCRAFT], dtype=np.float32))
            update_buffer(self.aclonbuf, np.array(data.lon[:MAX_NAIRCRAFT], dtype=np.float32))
            update_buffer(self.achdgbuf, np.array(data.trk[:MAX_NAIRCRAFT], dtype=np.float32))
            update_buffer(self.acaltbuf, np.array(data.alt[:MAX_NAIRCRAFT], dtype=np.float32))
            update_buffer(self.actasbuf, np.array(data.tas[:MAX_NAIRCRAFT], dtype=np.float32))
            update_buffer(self.asasnbuf, np.array(data.asasn[:MAX_NAIRCRAFT], dtype=np.float32))
            update_buffer(self.asasebuf, np.array(data.asase[:MAX_NAIRCRAFT], dtype=np.float32))

            # CPA lines to indicate conflicts
            ncpalines = np.count_nonzero(data.inconf)

            cpalines  = np.zeros(4 * ncpalines, dtype=np.float32)
            self.cpalines.set_vertex_count(2 * ncpalines)

            # Labels and colors
            rawlabel = ''
            color = np.empty((min(self.naircraft, MAX_NAIRCRAFT), 4), dtype=np.uint8)
            selssd = np.zeros(self.naircraft, dtype=np.uint8)
            confidx = 0

            zdata = zip(data.id, data.ingroup, data.inconf, data.tcpamax, data.trk, data.gs,
                        data.cas, data.vs, data.alt, data.lat, data.lon)
            for i, (acid, ingroup, inconf, tcpa, trk, gs, cas, vs, alt, lat, lon) in enumerate(zdata):

# Get custom color if available, else default
                    rgb = palette.aircraft
                    if ingroup:
                        for groupmask, groupcolor in actdata.custgrclr.items():
                            if ingroup & groupmask:
                                rgb = groupcolor
                                break
                    rgb = actdata.custacclr.get(acid, rgb)
                    color[i, :] = tuple(rgb) + (255,)

                #  Check if aircraft is selected to show SSD
                if actdata.ssd_all or acid in actdata.ssd_ownship:
                    selssd[i] = 255

            if len(actdata.ssd_ownship) > 0 or actdata.ssd_conflicts or actdata.ssd_all:
                update_buffer(self.ssd.selssdbuf, selssd[:MAX_NAIRCRAFT])

            update_buffer(self.confcpabuf, cpalines[:MAX_NCONFLICTS * 4])
            update_buffer(self.accolorbuf, color)
            update_buffer(self.aclblbuf, np.array(rawlabel.encode('utf8'), dtype=np.string_))

            # If there is a visible route, update the start position
            if self.route_acid != "":
                if self.route_acid in data.id:
                    idx = data.id.index(self.route_acid)
                    update_buffer(self.routebuf,
                                  np.array([data.lat[idx], data.lon[idx]], dtype=np.float32))

            # Update trails database with new lines
            if data.swtrails:
                actdata.traillat0.extend(data.traillat0)
                actdata.traillon0.extend(data.traillon0)

update_buffer(self.aclblbuf, np.array(rawlabel.encode('utf8'), dtype=np.string_))

            # If there is a visible route, update the start position
            if self.route_acid != "":
                if self.route_acid in data.id:
                    idx = data.id.index(self.route_acid)
                    update_buffer(self.routebuf,
                                  np.array([data.lat[idx], data.lon[idx]], dtype=np.float32))

            # Update trails database with new lines
            if data.swtrails:
                actdata.traillat0.extend(data.traillat0)
                actdata.traillon0.extend(data.traillon0)
                actdata.traillat1.extend(data.traillat1)
                actdata.traillon1.extend(data.traillon1)
                update_buffer(self.trailbuf, np.array(
                    list(zip(actdata.traillat0, actdata.traillon0,
                             actdata.traillat1, actdata.traillon1)) +
                    list(zip(data.traillastlat, data.traillastlon,
                             list(data.lat), list(data.lon))),
                    dtype=np.float32))

                self.traillines.set_vertex_count(2 * len(actdata.traillat0) +
                                                 2 * len(data.lat))

            else:
                actdata.traillat0 = []
                actdata.traillon0 = []
                actdata.traillat1 = []
                actdata.traillon1 = []

                self.traillines.set_vertex_count(0)

if ingroup:
                        for groupmask, groupcolor in actdata.custgrclr.items():
                            if ingroup & groupmask:
                                rgb = groupcolor
                                break
                    rgb = actdata.custacclr.get(acid, rgb)
                    color[i, :] = tuple(rgb) + (255,)

                #  Check if aircraft is selected to show SSD
                if actdata.ssd_all or acid in actdata.ssd_ownship:
                    selssd[i] = 255

            if len(actdata.ssd_ownship) > 0 or actdata.ssd_conflicts or actdata.ssd_all:
                update_buffer(self.ssd.selssdbuf, selssd[:MAX_NAIRCRAFT])

            update_buffer(self.confcpabuf, cpalines[:MAX_NCONFLICTS * 4])
            update_buffer(self.accolorbuf, color)
            update_buffer(self.aclblbuf, np.array(rawlabel.encode('utf8'), dtype=np.string_))

            # If there is a visible route, update the start position
            if self.route_acid != "":
                if self.route_acid in data.id:
                    idx = data.id.index(self.route_acid)
                    update_buffer(self.routebuf,
                                  np.array([data.lat[idx], data.lon[idx]], dtype=np.float32))

            # Update trails database with new lines
            if data.swtrails:
                actdata.traillat0.extend(data.traillat0)
                actdata.traillon0.extend(data.traillon0)
                actdata.traillat1.extend(data.traillat1)
                actdata.traillon1.extend(data.traillon1)

elif alt > actdata.translvl:
                        FL = int(round((alt / (100. * ft))))
                        txt += "FL%03d/" % FL
                    else:
                        txt += "%05d/" % int(round(alt / ft))

                    # Speed
                    if spd < 0:
                        txt += "--- "
                    elif spd>2.0:
                        txt += "%03d" % int(round(spd / kts))
                    else:
                        txt += "M{:.2f}".format(spd) # Mach number

                wpname += txt.ljust(24) # Fill out with spaces
            update_buffer(self.routelblbuf, np.array(
                            wpname.encode('ascii', 'ignore')))
        else:
            self.route.set_vertex_count(0)
            self.routelbl.n_instances = 0

#  Check if aircraft is selected to show SSD
                if actdata.ssd_all or acid in actdata.ssd_ownship:
                    selssd[i] = 255

            if len(actdata.ssd_ownship) > 0 or actdata.ssd_conflicts or actdata.ssd_all:
                update_buffer(self.ssd.selssdbuf, selssd[:MAX_NAIRCRAFT])

            update_buffer(self.confcpabuf, cpalines[:MAX_NCONFLICTS * 4])
            update_buffer(self.accolorbuf, color)
            update_buffer(self.aclblbuf, np.array(rawlabel.encode('utf8'), dtype=np.string_))

            # If there is a visible route, update the start position
            if self.route_acid != "":
                if self.route_acid in data.id:
                    idx = data.id.index(self.route_acid)
                    update_buffer(self.routebuf,
                                  np.array([data.lat[idx], data.lon[idx]], dtype=np.float32))

            # Update trails database with new lines
            if data.swtrails:
                actdata.traillat0.extend(data.traillat0)
                actdata.traillon0.extend(data.traillon0)
                actdata.traillat1.extend(data.traillat1)
                actdata.traillon1.extend(data.traillon1)
                update_buffer(self.trailbuf, np.array(
                    list(zip(actdata.traillat0, actdata.traillon0,
                             actdata.traillat1, actdata.traillon1)) +
                    list(zip(data.traillastlat, data.traillastlon,
                             list(data.lat), list(data.lon))),
                    dtype=np.float32))

                self.traillines.set_vertex_count(2 * len(actdata.traillat0) +