--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/graphics/opengl/gl-render.cc	Mon Feb 11 16:42:14 2008 +0100
@@ -0,0 +1,1396 @@
+/*
+
+Copyright (C) 2008 Michael Goffioul
+
+This file is part of Octave.
+
+Octave is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the
+Free Software Foundation; either version 3 of the License, or (at your
+option) any later version.
+
+Octave is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with Octave; see the file COPYING.  If not, see
+<http://www.gnu.org/licenses/>.
+
+*/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <lo-mappers.h>
+#include "gl-render.h"
+
+#include <GL/gl.h>
+#include <GL/glu.h>
+
+enum {
+  AXE_ANY_DIR   = 0,
+  AXE_DEPTH_DIR = 1,
+  AXE_HORZ_DIR  = 2,
+  AXE_VERT_DIR  = 3
+};
+void
+opengl_renderer::draw (const graphics_object& go)
+{
+  if (! go.valid_object ())
+    return;
+
+  const base_properties& props = go.get_properties ();
+
+  if (go.isa ("figure"))
+    draw (dynamic_cast<const figure::properties&> (props));
+  else if (go.isa ("axes"))
+    draw (dynamic_cast<const axes::properties&> (props));
+  else if (go.isa ("line"))
+    draw (dynamic_cast<const line::properties&> (props));
+  else
+    warning ("opengl_renderer: cannot render object of type `%s'",
+	     props.graphics_object_name ().c_str ());
+}
+
+void
+opengl_renderer::draw (const figure::properties& props)
+{
+  backend = props.get_backend ();
+
+  Matrix c = props.get_color_rgb ();
+
+  if (c.length() >= 3)
+    {
+      glClearColor (c(0), c(1), c(2), 1);
+      glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+    }
+
+  draw (props.get_children ());
+}
+
+void
+opengl_renderer::draw (const axes::properties& props)
+{
+  // setup OpenGL transformation
+
+  Matrix x_zlim = props.get_transform_zlim ();
+  Matrix x_mat1 = props.get_opengl_matrix_1 ();
+  Matrix x_mat2 = props.get_opengl_matrix_2 ();
+  
+  xZ1 = x_zlim(0)-(x_zlim(1)-x_zlim(0))/2;
+  xZ2 = x_zlim(1)+(x_zlim(1)-x_zlim(0))/2;
+
+  int vw[4];
+  glGetIntegerv (GL_VIEWPORT, vw);
+
+  glMatrixMode (GL_MODELVIEW);
+  glLoadIdentity ();
+  glScaled(1, 1, -1);
+  glMultMatrixd (x_mat1.data ());
+  glMatrixMode (GL_PROJECTION);
+  glLoadIdentity ();
+  glOrtho (0, vw[2], vw[3], 0, xZ1, xZ2);
+  glMultMatrixd (x_mat2.data ());
+  glMatrixMode (GL_MODELVIEW);
+
+  glClear (GL_DEPTH_BUFFER_BIT);
+
+  // store axes transformation data
+
+  xform = props.get_transform ();
+  
+  // draw axes object
+  
+  Matrix xlim = xform.xscale (props.get_xlim ().matrix_value ());
+  Matrix ylim = xform.yscale (props.get_ylim ().matrix_value ());
+  Matrix zlim = xform.zscale (props.get_zlim ().matrix_value ());
+  double xmin = xlim(0), xmax = xlim(1);
+  double ymin = ylim(0), ymax = ylim(1);
+  double zmin = zlim(0), zmax = zlim(1);
+  
+  double xd = (props.xdir_is ("normal") ? 1 : -1);
+  double yd = (props.ydir_is ("normal") ? 1 : -1);
+  double zd = (props.zdir_is ("normal") ? 1 : -1);
+
+  ColumnVector p1, p2, xv (3), yv (3), zv (3);
+  int xstate, ystate, zstate;
+
+  xstate = ystate = zstate = AXE_ANY_DIR;
+
+  p1 = xform.transform (xmin, (ymin+ymax)/2, (zmin+zmax)/2, false);
+  p2 = xform.transform (xmax, (ymin+ymax)/2, (zmin+zmax)/2, false);
+  xv(0) = xround (p2(0)-p1(0));
+  xv(1) = xround (p2(1)-p1(1));
+  xv(2) = (p2(2)-p1(2));
+  if (xv(0) == 0 && xv(1) == 0)
+    xstate = AXE_DEPTH_DIR;
+  else if (xv(2) == 0)
+    {
+      if (xv(0) == 0)
+        xstate = AXE_VERT_DIR;
+      else if (xv(1) == 0)
+        xstate = AXE_HORZ_DIR;
+    }
+  double xPlane;
+  if (xv(2) == 0)
+    if (xv(1) == 0)
+      xPlane = (xv(0) > 0 ? xmax : xmin);
+    else
+      xPlane = (xv(1) < 0 ? xmax : xmin);
+  else
+    xPlane = (xv(2) < 0 ? xmin : xmax);
+  double xPlaneN = (xPlane == xmin ? xmax : xmin);
+  double fx = (xmax-xmin)/sqrt(xv(0)*xv(0)+xv(1)*xv(1));
+
+  p1 = xform.transform ((xmin+xmax)/2, ymin, (zmin+zmax)/2, false);
+  p2 = xform.transform ((xmin+xmax)/2, ymax, (zmin+zmax)/2, false);
+  yv(0) = xround (p2(0)-p1(0));
+  yv(1) = xround (p2(1)-p1(1));
+  yv(2) = (p2(2)-p1(2));
+  if (yv(0) == 0 && yv(1) == 0)
+    ystate = AXE_DEPTH_DIR;
+  else if (yv(2) == 0)
+    {
+      if (yv(0) == 0)
+        ystate = AXE_VERT_DIR;
+      else if (yv(1) == 0)
+        ystate = AXE_HORZ_DIR;
+    }
+  double yPlane;
+  if (yv(2) == 0)
+    if (yv(1) == 0)
+      yPlane = (yv(0) > 0 ? ymax : ymin);
+    else
+      yPlane = (yv(1) < 0 ? ymax : ymin);
+  else
+    yPlane = (yv(2) < 0 ? ymin : ymax);
+  double yPlaneN = (yPlane == ymin ? ymax : ymin);
+  double fy = (ymax-ymin)/sqrt(yv(0)*yv(0)+yv(1)*yv(1));
+
+  p1 = xform.transform((xmin+xmax)/2, (ymin+ymax)/2, zmin, false);
+  p2 = xform.transform((xmin+xmax)/2, (ymin+ymax)/2, zmax, false);
+  zv(0) = xround(p2(0)-p1(0));
+  zv(1) = xround (p2(1)-p1(1));
+  zv(2) = (p2(2)-p1(2));
+  if (zv(0) == 0 && zv(1) == 0)
+    zstate = AXE_DEPTH_DIR;
+  else if (zv(2) == 0)
+  {
+    if (zv(0) == 0)
+      zstate = AXE_VERT_DIR;
+    else if (zv(1) == 0)
+      zstate = AXE_HORZ_DIR;
+  }
+  double zPlane;
+  if (zv(2) == 0)
+    if (zv(1) == 0)
+      zPlane = (zv(0) > 0 ? zmin : zmax);
+    else
+      zPlane = (zv(1) < 0 ? zmin : zmax);
+  else
+    zPlane = (zv(2) < 0 ? zmin : zmax);
+  double zPlaneN = (zPlane == zmin ? zmax : zmin);
+  double fz = (zmax-zmin)/sqrt(zv(0)*zv(0)+zv(1)*zv(1));
+
+  bool mode2d = (((xstate > AXE_DEPTH_DIR ? 1 : 0) +
+        (ystate > AXE_DEPTH_DIR ? 1 : 0) +
+        (zstate > AXE_DEPTH_DIR ? 1 : 0)) == 2);
+  if (props.tickdirmode_is ("auto"))
+  {
+    // FIXME: tickdir should be updated (code below comes
+    //        from JHandles)
+    //autoMode++;
+    //TickDir.set(mode2d ? "in" : "out", true);
+    //autoMode--;
+  }
+
+  // FIXME: use ticklength property
+  double xticklen = 7, yticklen = 7, zticklen = 7;
+
+  //double tickdir = (props.tickdir_is ("in") ? -1 : 1);
+  double tickdir = (props.tickdirmode_is ("auto") ?
+		    (mode2d ? -1 : 1) :
+		    (props.tickdir_is ("in") ? -1 : 1));
+  double xtickoffset = (mode2d && tickdir < 0 ? 0 : xticklen) + 5;
+  double ytickoffset = (mode2d && tickdir < 0 ? 0 : yticklen) + 5;
+  double ztickoffset = (mode2d && tickdir < 0 ? 0 : zticklen) + 5;
+
+  bool xySym = (xd*yd*(xPlane-xPlaneN)*(yPlane-yPlaneN) > 0);
+  bool x2Dtop = false;
+  bool y2Dright = false;
+  double zpTick = zPlane;
+
+  /* 2D mode */
+  if (xstate == AXE_HORZ_DIR && ystate == AXE_VERT_DIR)
+  {
+    if (props.xaxislocation_is ("top"))
+    {
+      double tmp = yPlane;
+      yPlane = yPlaneN;
+      yPlaneN = tmp;
+      x2Dtop = true;
+    }
+    if (props.yaxislocation_is ("right"))
+    {
+      double tmp = xPlane;
+      xPlane = xPlaneN;
+      xPlaneN = tmp;
+      y2Dright = true;
+    }
+    if (props.layer_is ("top"))
+      zpTick = zPlaneN;
+  }
+
+  Matrix axe_color = props.get_color_rgb ();
+  bool visible = props.is_visible ();
+  bool box = props.is_box ();
+
+  // Axes planes
+
+  if (axe_color.numel () > 0 && visible)
+    {
+      set_color (axe_color);
+      set_polygon_offset (true, 2.5);
+
+      glBegin (GL_QUADS);
+
+      // X plane
+      glVertex3d (xPlane, ymin, zmin);
+      glVertex3d (xPlane, ymax, zmin);
+      glVertex3d (xPlane, ymax, zmax);
+      glVertex3d (xPlane, ymin, zmax);
+
+      // Y plane
+      glVertex3d (xmin, yPlane, zmin);
+      glVertex3d (xmax, yPlane, zmin);
+      glVertex3d (xmax, yPlane, zmax);
+      glVertex3d (xmin, yPlane, zmax);
+
+      // Z plane
+      glVertex3d (xmin, ymin, zPlane);
+      glVertex3d (xmax, ymin, zPlane);
+      glVertex3d (xmax, ymax, zPlane);
+      glVertex3d (xmin, ymax, zPlane);
+
+      glEnd ();
+
+      set_polygon_offset (false);
+    }
+
+  // Axes box
+
+  set_linestyle ("-", true);
+  set_linewidth (props.get_linewidth ());
+
+  if (visible)
+    {
+      glBegin (GL_LINES);
+
+      // X box
+      set_color (props.get_xcolor_rgb ());
+      glVertex3d (xPlaneN, yPlaneN, zPlane);
+      glVertex3d (xPlane, yPlaneN, zPlane);
+      if (box)
+        {
+          glVertex3d (xPlaneN, yPlane, zPlane);
+          glVertex3d (xPlane, yPlane, zPlane);
+          glVertex3d (xPlaneN, yPlane, zPlaneN);
+          glVertex3d (xPlane, yPlane, zPlaneN);
+          glVertex3d (xPlaneN, yPlaneN, zPlaneN);
+          glVertex3d (xPlane, yPlaneN, zPlaneN);
+        }
+
+      // Y box
+      set_color (props.get_ycolor_rgb ());
+      glVertex3d (xPlaneN, yPlaneN, zPlane);
+      glVertex3d (xPlaneN, yPlane, zPlane);
+      if (box)
+        {
+          glVertex3d (xPlane, yPlaneN, zPlane);
+          glVertex3d (xPlane, yPlane, zPlane);
+          glVertex3d (xPlane, yPlaneN, zPlaneN);
+          glVertex3d (xPlane, yPlane, zPlaneN);
+          glVertex3d (xPlaneN, yPlaneN, zPlaneN);
+          glVertex3d (xPlaneN, yPlane, zPlaneN);
+        }
+
+      // Z box
+      set_color (props.get_zcolor_rgb ());
+      if (xySym)
+        {
+          glVertex3d (xPlaneN, yPlane, zPlaneN);
+          glVertex3d (xPlaneN, yPlane, zPlane);
+        }
+      else
+        {
+          glVertex3d (xPlane, yPlaneN, zPlaneN);
+          glVertex3d (xPlane, yPlaneN, zPlane);
+        }
+      if (box)
+        {
+          glVertex3d (xPlane, yPlane, zPlaneN);
+          glVertex3d (xPlane, yPlane, zPlane);
+          if (xySym)
+            {
+              glVertex3d (xPlane, yPlaneN, zPlaneN);
+              glVertex3d (xPlane, yPlaneN, zPlane);
+            }
+          else
+            {
+              glVertex3d (xPlaneN, yPlane, zPlaneN);
+              glVertex3d (xPlaneN, yPlane, zPlane);
+            }
+          glVertex3d (xPlaneN, yPlaneN, zPlaneN);
+          glVertex3d (xPlaneN, yPlaneN, zPlane);
+        }
+
+      glEnd ();
+    }
+
+  std::string gridstyle = props.get_gridlinestyle ();
+  std::string minorgridstyle = props.get_minorgridlinestyle ();
+
+  // X grid
+
+  if (visible && xstate != AXE_DEPTH_DIR)
+    {
+      bool do_xgrid = (props.is_xgrid () && (gridstyle != "none"));
+      bool do_xminorgrid = (props.is_xminorgrid () && (minorgridstyle != "none"));
+      bool do_xminortick = props.is_xminortick ();
+      Matrix xticks = xform.xscale (props.get_xtick ().matrix_value ());
+      // FIXME: use pre-computed minor ticks
+      Matrix xmticks;
+      // FIXME: use xticklabels property
+      string_vector xticklabels;
+      int wmax = 0, hmax = 0;
+      bool tick_along_z = xisinf (fy);
+      Matrix tickpos (xticks.numel (), 3);
+
+      set_color (props.get_xcolor_rgb ());
+
+      // grid lines
+      if (do_xgrid)
+        {
+          set_linestyle (gridstyle, true);
+          glBegin (GL_LINES);
+          for (int i = 0; i < xticks.numel (); i++)
+            {
+              double xval = xticks(i);
+
+              glVertex3d (xval, yPlaneN, zpTick);
+              glVertex3d (xval, yPlane, zpTick);
+              if (zstate != AXE_DEPTH_DIR)
+                {
+                  glVertex3d (xval, yPlane, zPlaneN);
+                  glVertex3d (xval, yPlane, zPlane);
+                }
+            }
+          glEnd ();
+          set_linestyle ("-", true);
+        }
+
+      // tick marks
+      if (tick_along_z)
+        {
+          glBegin (GL_LINES);
+          for (int i = 0; i < xticks.numel (); i++)
+            {
+              double xval = xticks(i);
+
+              glVertex3d (xval, yPlaneN, zPlane);
+              glVertex3d (xval, yPlaneN, zPlane+signum(zPlane-zPlaneN)*fz*xticklen*tickdir);
+              if (box && xstate != AXE_ANY_DIR)
+                {
+                  glVertex3d (xval, yPlaneN, zPlaneN);
+                  glVertex3d (xval, yPlaneN,
+                        zPlaneN+signum(zPlaneN-zPlane)*fz*xticklen*tickdir);
+                }
+              tickpos(i,0) = xval;
+              tickpos(i,1) = yPlaneN;
+              tickpos(i,2) = zPlane+signum(zPlane-zPlaneN)*fz*xtickoffset;
+            }
+          glEnd ();
+        }
+      else
+        {
+          glBegin (GL_LINES);
+          for (int i = 0; i < xticks.numel (); i++)
+            {
+              double xval = xticks(i);
+
+              glVertex3d (xval, yPlaneN, zpTick);
+              glVertex3d (xval, yPlaneN+signum(yPlaneN-yPlane)*fy*xticklen*tickdir, zpTick);
+              if (box && xstate != AXE_ANY_DIR)
+                {
+                  glVertex3d (xval, yPlane, zpTick);
+                  glVertex3d (xval,
+                        yPlane+signum(yPlane-yPlaneN)*fy*xticklen*tickdir, zpTick);
+                }
+              tickpos(i,0) = xval;
+              tickpos(i,1) = yPlaneN+signum(yPlaneN-yPlane)*fy*xtickoffset;
+              tickpos(i,2) = zPlane;
+            }
+          glEnd ();
+        }
+
+      // FIXME: tick texts
+
+      // minor grid lines
+      if (do_xminorgrid)
+        {
+          set_linestyle (minorgridstyle, true);
+          glBegin (GL_LINES);
+          for (int i = 0; i < xmticks.numel (); i++)
+            {
+              double xval = xmticks(i);
+
+              glVertex3d (xval, yPlaneN, zpTick);
+              glVertex3d (xval, yPlane, zpTick);
+              if (zstate != AXE_DEPTH_DIR)
+                {
+                  glVertex3d (xval, yPlane, zPlaneN);
+                  glVertex3d (xval, yPlane, zPlane);
+                }
+            }
+          glEnd ();
+          set_linestyle ("-", true);
+        }
+			
+      // minor tick marks
+      if (do_xminortick)
+        {
+          if (tick_along_z)
+            {
+              glBegin (GL_LINES);
+              for (int i = 0; i < xmticks.numel (); i++)
+                {
+                  double xval = xmticks(i);
+
+                  glVertex3d (xval, yPlaneN, zPlane);
+                  glVertex3d (xval, yPlaneN,
+                      zPlane+signum(zPlane-zPlaneN)*fz*xticklen/2*tickdir);
+                  if (box && xstate != AXE_ANY_DIR)
+                    {
+                      glVertex3d (xval, yPlaneN, zPlaneN);
+                      glVertex3d (xval, yPlaneN,
+                          zPlaneN+signum(zPlaneN-zPlane)*fz*xticklen/2*tickdir);
+                    }
+                }
+              glEnd ();
+            }
+          else
+            {
+              glBegin (GL_LINES);
+              for (int i = 0; i < xmticks.numel (); i++)
+                {
+                  double xval = xmticks(i);
+
+                  glVertex3d (xval, yPlaneN, zpTick);
+                  glVertex3d (xval,
+                        yPlaneN+signum(yPlaneN-yPlane)*fy*xticklen/2*tickdir, zpTick);
+                  if (box && xstate != AXE_ANY_DIR)
+                    {
+                      glVertex3d (xval, yPlane, zpTick);
+                      glVertex3d (xval,
+                            yPlane+signum(yPlane-yPlaneN)*fy*xticklen/2*tickdir, zpTick);
+                    }
+                }
+              glEnd ();
+            }
+        }
+
+      text::properties& xlabel_props =
+        reinterpret_cast<text::properties&> (gh_manager::get_object (props.get_xlabel ()).get_properties ());
+
+      // FIXME: auto-positioning should be disabled if the 
+      //        label has been positioned manually
+      if (! xlabel_props.get_string ().empty ())
+        {
+          xlabel_props.set_horizontalalignment (xstate > AXE_DEPTH_DIR ? "center" : (xySym ? "left" : "right"));
+	  xlabel_props.set_verticalalignment (xstate == AXE_VERT_DIR ? "bottom" : (zd*zv(2) <= 0 ? "top" : "bottom"));
+
+          double angle = 0;
+          ColumnVector p = graphics_xform::xform_vector ((xmin+xmax)/2, yPlaneN, zPlane);
+
+          if (tick_along_z)
+            p(2) += (signum(zPlane-zPlaneN)*fz*xtickoffset);
+          else
+            p(1) += (signum(yPlaneN-yPlane)*fy*xtickoffset);
+          p = xform.transform (p(0), p(1), p(2), false);
+          switch (xstate)
+            {
+              case AXE_ANY_DIR:
+                p(0) += (xySym ? wmax : -wmax);
+                p(1) += (zd*zv(2) <= 0 ? hmax : -hmax);
+                break;
+              case AXE_VERT_DIR:
+                p(0) -= wmax;
+                angle = 90;
+                break;
+              case AXE_HORZ_DIR:
+                p(1) += hmax;
+                break;
+            }
+          p = xform.untransform (p(0), p(1), p(2), true);
+          xlabel_props.set_position (p.extract_n (0, 3).transpose ());
+          xlabel_props.set_rotation (angle);
+        }
+    }
+
+  // Y grid
+		
+  if (ystate != AXE_DEPTH_DIR && visible)
+    {
+      bool do_ygrid = (props.is_ygrid () && (gridstyle != "none"));
+      bool do_yminorgrid = (props.is_yminorgrid () && (minorgridstyle != "none"));
+      bool do_yminortick = props.is_yminortick ();
+      Matrix yticks = xform.yscale (props.get_ytick ().matrix_value ());
+      // FIXME: use pre-computed minor ticks
+      Matrix ymticks;
+      // FIXME: use yticklabels property
+      string_vector yticklabels;
+      int wmax = 0, hmax = 0;
+      bool tick_along_z = xisinf (fx);
+      Matrix tickpos (yticks.numel (), 3);
+
+      set_color (props.get_ycolor_rgb ());
+
+      // grid lines
+      if (do_ygrid)
+        {
+          set_linestyle (gridstyle, true);
+          glBegin (GL_LINES);
+          for (int i = 0; i < yticks.numel (); i++)
+            {
+              double yval = yticks(i);
+
+              glVertex3d (xPlaneN, yval, zpTick);
+              glVertex3d (xPlane, yval, zpTick);
+              if (zstate != AXE_DEPTH_DIR)
+                {
+                  glVertex3d (xPlane, yval, zPlaneN);
+                  glVertex3d (xPlane, yval, zPlane);
+                }
+            }
+          glEnd ();
+          set_linestyle ("-", true);
+        }
+
+      // tick marks
+      if (tick_along_z)
+        {
+          glBegin (GL_LINES);
+          for (int i = 0; i < yticks.numel (); i++)
+            {
+              double yval = yticks(i);
+
+              glVertex3d (xPlaneN, yval, zPlane);
+              glVertex3d (xPlaneN, yval, zPlane+signum(zPlane-zPlaneN)*fz*yticklen*tickdir);
+              if (box && ystate != AXE_ANY_DIR)
+                {
+                  glVertex3d (xPlaneN, yval, zPlaneN);
+                  glVertex3d (xPlaneN, yval,
+                        zPlaneN+signum(zPlaneN-zPlane)*fz*yticklen*tickdir);
+                }
+              tickpos(i,0) = xPlaneN;
+              tickpos(i,1) = yval;
+              tickpos(i,2) = zPlane+signum(zPlane-zPlaneN)*fz*ytickoffset;
+            }
+          glEnd ();
+        }
+      else
+        {
+          glBegin (GL_LINES);
+          for (int i = 0; i < yticks.numel (); i++)
+            {
+              double yval = yticks(i);
+
+              glVertex3d (xPlaneN, yval, zpTick);
+              glVertex3d (xPlaneN+signum(xPlaneN-xPlane)*fx*yticklen*tickdir, yval, zpTick);
+              if (box && ystate != AXE_ANY_DIR)
+                {
+                  glVertex3d (xPlane, yval, zpTick);
+                  glVertex3d (xPlane+signum(xPlane-xPlaneN)*fx*yticklen*tickdir,
+                        yval, zpTick);
+                }
+              tickpos(i,0) = xPlaneN+signum(xPlaneN-xPlane)*fx*ytickoffset;
+              tickpos(i,1) = yval;
+              tickpos(i,2) = zPlane;
+            }
+          glEnd ();
+        }
+
+      // FIXME: tick texts
+
+      // minor grid lines
+      if (do_yminorgrid)
+        {
+          set_linestyle (minorgridstyle, true);
+          glBegin (GL_LINES);
+          for (int i = 0; i < ymticks.numel (); i++)
+            {
+              double yval = ymticks(i);
+
+              glVertex3d (xPlaneN, yval, zpTick);
+              glVertex3d (xPlane, yval, zpTick);
+              if (zstate != AXE_DEPTH_DIR)
+                {
+                  glVertex3d (xPlane, yval, zPlaneN);
+                  glVertex3d (xPlane, yval, zPlane);
+                }
+            }
+          glEnd ();
+          set_linestyle ("-", true);
+        }
+
+      // minor tick marks
+      if (do_yminortick)
+        {
+          if (tick_along_z)
+            {
+              glBegin (GL_LINES);
+              for (int i = 0; i < ymticks.numel (); i++)
+                {
+                  double yval = ymticks(i);
+
+                  glVertex3d (xPlaneN, yval, zPlane);
+                  glVertex3d (xPlaneN, yval,
+                        zPlane+signum(zPlane-zPlaneN)*fz*yticklen/2*tickdir);
+                  if (box && ystate != AXE_ANY_DIR)
+                    {
+                      glVertex3d (xPlaneN, yval, zPlaneN);
+                      glVertex3d (xPlaneN, yval,
+                            zPlaneN+signum(zPlaneN-zPlane)*fz*yticklen/2*tickdir);
+                    }
+                }
+              glEnd ();
+            }
+          else
+            {
+              glBegin (GL_LINES);
+              for (int i = 0; i < ymticks.numel (); i++)
+                {
+                  double yval = ymticks(i);
+
+                  glVertex3d (xPlaneN, yval, zpTick);
+                  glVertex3d (xPlaneN+signum(xPlaneN-xPlane)*fx*yticklen/2*tickdir,
+                        yval, zpTick);
+                  if (box && ystate != AXE_ANY_DIR)
+                    {
+                      glVertex3d (xPlane, yval, zpTick);
+                      glVertex3d (xPlane+signum(xPlane-xPlaneN)*fx*yticklen/2*tickdir,
+                            yval, zpTick);
+                    }
+                }
+              glEnd ();
+            }
+        }
+
+      text::properties& ylabel_props =
+        reinterpret_cast<text::properties&> (gh_manager::get_object (props.get_ylabel ()).get_properties ());
+
+      // FIXME: auto-positioning should be disabled if the 
+      //        label has been positioned manually
+      if (! ylabel_props.get_string ().empty ())
+        {
+          ylabel_props.set_horizontalalignment (ystate > AXE_DEPTH_DIR ? "center" : (!xySym ? "left" : "right"));
+	  ylabel_props.set_verticalalignment (ystate == AXE_VERT_DIR ? "bottom" : (zd*zv(2) <= 0 ? "top" : "bottom"));
+
+          double angle = 0;
+          ColumnVector p = graphics_xform::xform_vector (xPlaneN, (ymin+ymax)/2, zPlane);
+
+          if (tick_along_z)
+            p(2) += (signum(zPlane-zPlaneN)*fz*ytickoffset);
+          else
+            p(0) += (signum(xPlaneN-xPlane)*fx*ytickoffset);
+          p = xform.transform (p(0), p(1), p(2), false);
+          switch (ystate)
+            {
+              case AXE_ANY_DIR:
+                p(0) += (!xySym ? wmax : -wmax);
+                p(1) += (zd*zv(2) <= 0 ? hmax : -hmax);
+                break;
+              case AXE_VERT_DIR:
+                p(0) -= wmax;
+                angle = 90;
+                break;
+              case AXE_HORZ_DIR:
+                p(1) += hmax;
+                break;
+            }
+          p = xform.untransform(p(0), p(1), p(2), true);
+          ylabel_props.set_position (p.extract_n (0, 3).transpose ());
+          ylabel_props.set_rotation (angle);
+        }
+    }
+		
+  // Z Grid
+
+  if (zstate != AXE_DEPTH_DIR && visible)
+    {
+      bool do_zgrid = (props.is_zgrid () && (gridstyle != "none"));
+      bool do_zminorgrid = (props.is_zminorgrid () && (minorgridstyle != "none"));
+      bool do_zminortick = props.is_zminortick ();
+      Matrix zticks = xform.zscale (props.get_ztick ().matrix_value ());
+      // FIXME: use pre-computed minor ticks
+      Matrix zmticks;
+      // FIXME: use zticklabels property
+      string_vector zticklabels;
+      int wmax = 0, hmax = 0;
+      Matrix tickpos (zticks.numel (), 3);
+
+      set_color (props.get_zcolor_rgb ());
+
+      // grid lines
+      if (do_zgrid)
+        {
+          set_linestyle (gridstyle, true);
+          glBegin (GL_LINES);
+          for (int i = 0; i < zticks.numel (); i++)
+            {
+              double zval = zticks(i);
+
+              glVertex3d (xPlaneN, yPlane, zval);
+              glVertex3d (xPlane, yPlane, zval);
+              glVertex3d (xPlane, yPlaneN, zval);
+              glVertex3d (xPlane, yPlane, zval);
+            }
+          glEnd ();
+          set_linestyle ("-", true);
+        }
+
+      // tick marks
+      if (xySym)
+        {
+          if (xisinf (fy))
+            {
+              glBegin (GL_LINES);
+              for (int i = 0; i < zticks.numel (); i++)
+                {
+                  double zval = zticks(i);
+
+                  glVertex3d (xPlaneN, yPlane, zval);
+                  glVertex3d (xPlaneN+signum(xPlaneN-xPlane)*fx*zticklen*tickdir,
+                        yPlane, zval);
+                  if (box && zstate != AXE_ANY_DIR)
+                    {
+                      glVertex3d (xPlane, yPlane, zval);
+                      glVertex3d (xPlane+signum(xPlane-xPlaneN)*fx*zticklen*tickdir,
+                            yPlane, zval);
+                    }
+                  tickpos(i,0) = xPlaneN+signum(xPlaneN-xPlane)*fx*ztickoffset;
+                  tickpos(i,1) = yPlane;
+                  tickpos(i,2) = zval;
+                }
+              glEnd ();
+            }
+          else
+            {
+              glBegin (GL_LINES);
+              for (int i = 0; i < zticks.numel (); i++)
+                {
+                  double zval = zticks(i);
+
+                  glVertex3d (xPlaneN, yPlane, zval);
+                  glVertex3d (xPlaneN, yPlane+signum(yPlane-yPlaneN)*fy*zticklen*tickdir, zval);
+                  tickpos(i,0) = xPlaneN;
+                  tickpos(i,1) = yPlane+signum(yPlane-yPlaneN)*fy*ztickoffset;
+                  tickpos(i,2) = zval;
+                }
+              glEnd ();
+            }
+        }
+      else
+        {
+          if (xisinf (fx))
+            {
+              glBegin (GL_LINES);
+              for (int i = 0; i < zticks.numel (); i++)
+                {
+                  double zval = zticks(i);
+
+                  glVertex3d (xPlane, yPlaneN, zval);
+                  glVertex3d (xPlane, yPlaneN+signum(yPlaneN-yPlane)*fy*zticklen*tickdir, zval);
+                  if (box && zstate != AXE_ANY_DIR)
+                    {
+                      glVertex3d (xPlane, yPlane, zval);
+                      glVertex3d (xPlane, yPlane+signum(yPlane-yPlaneN)*fy*zticklen*tickdir, zval);
+                    }
+                  tickpos(i,0) = xPlane;
+                  tickpos(i,1) = yPlaneN+signum(yPlaneN-yPlane)*fy*ztickoffset;
+                  tickpos(i,2) = zval;
+                }
+              glEnd ();
+            }
+          else
+          {
+            glBegin (GL_LINES);
+            for (int i = 0; i < zticks.numel (); i++)
+              {
+                double zval = zticks(i);
+
+                glVertex3d (xPlane, yPlaneN, zval);
+                glVertex3d (xPlane+signum(xPlane-xPlaneN)*fx*zticklen*tickdir, yPlaneN, zval);
+                tickpos(i,0) = xPlane+signum(xPlane-xPlaneN)*fx*ztickoffset;
+                tickpos(i,1) = yPlaneN;
+                tickpos(i,2) = zval;
+              }
+            glEnd ();
+          }
+        }
+
+      // FIXME: tick texts
+
+      // minor grid lines
+      if (do_zminorgrid)
+        {
+          set_linestyle (minorgridstyle, true);
+          glBegin (GL_LINES);
+          for (int i = 0; i < zmticks.numel (); i++)
+            {
+              double zval = zmticks(i);
+
+              glVertex3d (xPlaneN, yPlane, zval);
+              glVertex3d (xPlane, yPlane, zval);
+              glVertex3d (xPlane, yPlaneN, zval);
+              glVertex3d (xPlane, yPlane, zval);
+            }
+          glEnd ();
+          set_linestyle ("-", true);
+        }
+
+      // minor tick marks
+      if (do_zminortick)
+        {
+          if (xySym)
+            {
+              if (xisinf (fy))
+                {
+                  glBegin (GL_LINES);
+                  for (int i = 0; i < zmticks.numel (); i++)
+                    {
+                      double zval = zmticks(i);
+
+                      glVertex3d (xPlaneN, yPlane, zval);
+                      glVertex3d (xPlaneN+signum(xPlaneN-xPlane)*fx*zticklen/2*tickdir,
+                            yPlane, zval);
+                      if (box && zstate != AXE_ANY_DIR)
+                        {
+                          glVertex3d (xPlane, yPlane, zval);
+                          glVertex3d (xPlane+signum(xPlane-xPlaneN)*fx*zticklen/2*tickdir,
+                                yPlane, zval);
+                        }
+                    }
+                  glEnd ();
+                }
+              else
+                {
+                  glBegin (GL_LINES);
+                  for (int i = 0; i < zmticks.numel (); i++)
+                    {
+                      double zval = zmticks(i);
+
+                      glVertex3d (xPlaneN, yPlane, zval);
+                      glVertex3d (xPlaneN, yPlane+signum(yPlane-yPlaneN)*fy*zticklen/2*tickdir, zval);
+                    }
+                  glEnd ();
+                }
+            }
+          else
+            {
+              if (xisinf (fx))
+                {
+                  glBegin (GL_LINES);
+                  for (int i = 0; i < zmticks.numel (); i++)
+                    {
+                      double zval = zmticks(i);
+
+                      glVertex3d (xPlane, yPlaneN, zval);
+                      glVertex3d (xPlane, yPlaneN+signum(yPlaneN-yPlane)*fy*zticklen/2*tickdir, zval);
+                      if (box && zstate != AXE_ANY_DIR)
+                        {
+                          glVertex3d (xPlane, yPlane, zval);
+                          glVertex3d (xPlane, yPlane+signum(yPlane-yPlaneN)*fy*zticklen/2*tickdir, zval);
+                        }
+                    }
+                  glEnd ();
+                }
+              else
+                {
+                  glBegin (GL_LINES);
+                  for (int i = 0; i < zmticks.numel (); i++)
+                    {
+                      double zval = zmticks(i);
+
+                      glVertex3d (xPlane, yPlaneN, zval);
+                      glVertex3d (xPlane+signum(xPlane-xPlaneN)*fx*zticklen/2*tickdir, yPlaneN, zval);
+                    }
+                  glEnd ();
+                }
+            }
+        }
+
+      text::properties& zlabel_props =
+        reinterpret_cast<text::properties&> (gh_manager::get_object (props.get_zlabel ()).get_properties ());
+
+      // FIXME: auto-positioning should be disabled if the 
+      //        label has been positioned manually
+      if (! zlabel_props.get_string ().empty ())
+        {
+          bool camAuto = props.cameraupvectormode_is ("auto");
+
+          zlabel_props.set_horizontalalignment ((zstate > AXE_DEPTH_DIR || camAuto) ? "center" : "right");
+	  zlabel_props.set_verticalalignment(zstate == AXE_VERT_DIR ? "bottom" : ((zd*zv(2) < 0 || camAuto) ? "bottom" : "top"));
+
+          double angle = 0;
+          ColumnVector p;
+
+          if (xySym)
+            {
+              p = graphics_xform::xform_vector (xPlaneN, yPlane, (zmin+zmax)/2);
+              if (xisinf (fy))
+                p(0) += (signum(xPlaneN-xPlane)*fx*ztickoffset);
+              else
+                p(1) += (signum(yPlane-yPlaneN)*fy*ztickoffset);
+            }
+          else
+            {
+              p = graphics_xform::xform_vector (xPlane, yPlaneN, (zmin+zmax)/2);
+              if (xisinf (fx))
+                p(1) += (signum(yPlaneN-yPlane)*fy*ztickoffset);
+              else
+                p(0) += (signum(xPlane-xPlaneN)*fx*ztickoffset);
+            }
+          p = xform.transform (p(0), p(1), p(2), false);
+          switch (zstate)
+            {
+              case AXE_ANY_DIR:
+                if (camAuto)
+                  {
+                    p(0) -= wmax;
+                    angle = 90;
+                  }
+                /* FIXME: what's the correct offset?
+                   p[0] += (!xySym ? wmax : -wmax);
+                   p[1] += (zd*zv[2] <= 0 ? hmax : -hmax);
+                   */
+                break;
+              case AXE_VERT_DIR:
+                p(0) -= wmax;
+                angle = 90;
+                break;
+              case AXE_HORZ_DIR:
+                p(1) += hmax;
+                break;
+            }
+          p = xform.untransform (p(0), p(1), p(2), true);
+          zlabel_props.set_position (p.extract_n (0, 3).transpose ());
+          zlabel_props.set_rotation (angle);
+        }
+    }
+
+  set_linestyle ("-");
+
+  // Title
+
+  text::properties& title_props =
+    reinterpret_cast<text::properties&> (gh_manager::get_object (props.get_title ()).get_properties ());
+      
+  // FIXME: auto-positioning should be disabled if the 
+  //        title has been positioned manually
+  if (! title_props.get_string ().empty ())
+    {
+      Matrix bb = props.get_boundingbox (true);
+      ColumnVector p = xform.untransform (bb(0)+bb(2)/2, (bb(1)-10),
+          (x_zlim(0)+x_zlim(1))/2, true);
+      title_props.set_position (p.extract_n(0, 3).transpose ());
+    }
+
+  set_clipbox (xmin, xmax, ymin, ymax, zmin, zmax);
+
+  // Children
+
+  Matrix children = props.get_children ();
+  std::list<graphics_object> obj_list;
+  std::list<graphics_object>::iterator it;
+
+  // 1st pass: draw light objects
+
+  for (int i = 0; i < children.numel (); i++)
+    {
+      graphics_object go = gh_manager::get_object (children (i));
+
+      if (go.get_properties ().is_visible ())
+        {
+          if (go.isa ("light"))
+	    draw (go);
+          else
+            obj_list.push_back (go);
+        }
+    }
+
+  // 2nd pass: draw other objects (with units set to "data")
+
+  it = obj_list.begin ();
+  while (it != obj_list.end ())
+    {
+      graphics_object go = (*it);
+
+      // FIXME: check whether object has "units" property and it is set to "data"
+      if (! go.isa ("text") || go.get ("units").string_value () == "data")
+        {
+          set_clipping (go.get_properties ().is_clipping ());
+          draw (go);
+
+          it = obj_list.erase (it);
+        }
+      else
+        it++;
+    }
+
+  // 3rd pass: draw remaining objects
+
+  for (it = obj_list.begin (); it != obj_list.end (); it++)
+    {
+      graphics_object go = (*it);
+
+      set_clipping (go.get_properties ().is_clipping ());
+      draw (go);
+    }
+
+  set_clipping (false);
+  // FIXME: finalize rendering (transparency processing)
+  // FIXME: draw zoom box, if needed
+}
+
+void
+opengl_renderer::draw (const line::properties& props)
+{
+  Matrix x = xform.xscale (props.get_xdata ().matrix_value ());
+  Matrix y = xform.yscale (props.get_ydata ().matrix_value ());
+  Matrix z = xform.zscale (props.get_zdata ().matrix_value ());
+
+  bool has_z = (z.numel () > 0);
+  int n = static_cast<int> (::xmin (::xmin (x.numel (), y.numel ()), (has_z ? z.numel () : INT_MAX)));
+  octave_uint8 clip_mask = (props.is_clipping () ? 0x7F : 0x40), clip_ok (0x40);
+
+  std::vector<octave_uint8> clip (n);
+
+  if (has_z)
+    for (int i = 0; i < n; i++)
+      clip[i] = (clip_code (x(i), y(i), z(i)) & clip_mask);
+  else
+    {
+      double z_mid = (zmin+zmax)/2;
+
+      for (int i = 0; i < n; i++)
+	clip[i] = (clip_code (x(i), y(i), z_mid) & clip_mask);
+    }
+
+  if (! props.linestyle_is ("none"))
+    {
+      set_color (props.get_color_rgb ());
+      set_linestyle (props.get_linestyle (), false);
+      set_linewidth (props.get_linewidth ());
+
+      if (has_z)
+	{
+	  bool flag = false;
+
+	  for (int i = 1; i < n; i++)
+	    {
+	      if ((clip[i-1] & clip[i]) == clip_ok)
+		{
+		  if (! flag)
+		    {
+		      flag = true;
+		      glBegin (GL_LINE_STRIP);
+		      glVertex3d (x(i-1), y(i-1), z(i-1));
+		    }
+		  glVertex3d (x(i), y(i), z(i));
+		}
+	      else if (flag)
+		{
+		  flag = false;
+		  glEnd ();
+		}
+	    }
+
+	  if (flag)
+	    glEnd ();
+	}
+      else
+	{
+	  bool flag = false;
+
+	  for (int i = 1; i < n; i++)
+	    {
+	      if ((clip[i-1] & clip[i]) == clip_ok)
+		{
+		  if (! flag)
+		    {
+		      flag = true;
+		      glBegin (GL_LINE_STRIP);
+		      glVertex2d (x(i-1), y(i-1));
+		    }
+		  glVertex2d (x(i), y(i));
+		}
+	      else if (flag)
+		{
+		  flag = false;
+		  glEnd ();
+		}
+	    }
+
+	  if (flag)
+	    glEnd ();
+	}
+	  
+      set_linewidth (0.5);
+      set_linestyle ("-");
+    }
+
+  set_clipping (false);
+
+  if (! props.marker_is ("none") &&
+      ! (props.markeredgecolor_is ("none")
+	 && props.markerfacecolor_is ("none")))
+    {
+      Matrix lc, fc;
+
+      if (props.markeredgecolor_is ("auto"))
+	lc = props.get_color_rgb ();
+      else if (! props.markeredgecolor_is ("none"))
+	lc = props.get_markeredgecolor_rgb ();
+
+      if (props.markerfacecolor_is ("auto"))
+	fc = props.get_color_rgb ();
+      else if (! props.markerfacecolor_is ("none"))
+	fc = props.get_markerfacecolor_rgb ();
+
+      init_marker (props.get_marker (), props.get_markersize (),
+		   props.get_linewidth ());
+
+      for (int i = 0; i < n; i++)
+        {
+          if (clip[i] == clip_ok)
+            draw_marker (x(i), y(i), (has_z ? z(i) : 0), lc, fc);
+        }
+
+      end_marker ();
+    }
+
+  set_clipping (props.is_clipping ());
+}
+
+void
+opengl_renderer::set_viewport (int w, int h)
+{
+  glViewport (0, 0, w, h);
+}
+
+void
+opengl_renderer::set_color (const Matrix& c)
+{
+  glColor3dv (c.data ());
+}
+
+void
+opengl_renderer::set_polygon_offset (bool on, double offset)
+{
+  if (on)
+    {
+      glPolygonOffset (offset, offset);
+      glEnable (GL_POLYGON_OFFSET_FILL);
+    }
+  else
+    glDisable (GL_POLYGON_OFFSET_FILL);
+}
+
+void
+opengl_renderer::set_linewidth (float w)
+{
+  glLineWidth (w);
+}
+
+void
+opengl_renderer::set_linestyle (const std::string& s, bool use_stipple)
+{
+  bool solid = false;
+
+  if (s == "-")
+    {
+      glLineStipple (1, static_cast<unsigned short> (0xFFFF));
+      solid = true;
+    }
+  else if (s == ":")
+    glLineStipple (1, static_cast<unsigned short> (0x8888));
+  else if (s == "--")
+    glLineStipple (1, static_cast<unsigned short> (0x0FFF));
+  else if (s == "-.")
+    glLineStipple (1, static_cast<unsigned short> (0x020F));
+  else
+    glLineStipple (1, static_cast<unsigned short> (0x0000));
+
+  if (solid && ! use_stipple)
+    glDisable (GL_LINE_STIPPLE);
+  else
+    glEnable (GL_LINE_STIPPLE);
+}
+
+void
+opengl_renderer::set_clipbox (double x1, double x2, double y1, double y2,
+			      double z1, double z2)
+{
+  double dx = (x2-x1);
+  double dy = (y2-y1);
+  double dz = (z2-z1);
+
+  x1 -= 0.001*dx; x2 += 0.001*dx;
+  y1 -= 0.001*dy; y2 += 0.001*dy;
+  z1 -= 0.001*dz; z2 += 0.001*dz;
+
+  ColumnVector p (4, 0.0);
+
+  p(0) = -1; p(3) = x2;
+  glClipPlane (GL_CLIP_PLANE0, p.data ());
+  p(0) = 1; p(3) = -x1;
+  glClipPlane (GL_CLIP_PLANE1, p.data ());
+  p(0) = 0; p(1) = -1; p(3) = y2;
+  glClipPlane (GL_CLIP_PLANE2, p.data ());
+  p(1) = 1; p(3) = -y1;
+  glClipPlane (GL_CLIP_PLANE3, p.data ());
+  p(1) = 0; p(2) = -1; p(3) = z2;
+  glClipPlane (GL_CLIP_PLANE4, p.data ());
+  p(2) = 1; p(3) = -z1;
+  glClipPlane (GL_CLIP_PLANE5, p.data ());
+
+  xmin = x1; xmax = x2;
+  ymin = y1; ymax = y2;
+  zmin = z1; zmax = z2;
+}
+
+void
+opengl_renderer::set_clipping (bool enable)
+{
+  bool has_clipping = (glIsEnabled (GL_CLIP_PLANE0) == GL_TRUE);
+
+  if (enable != has_clipping)
+    {
+      if (enable)
+        for (int i = 0; i < 6; i++)
+          glEnable (GL_CLIP_PLANE0+i);
+      else
+        for (int i = 0; i < 6; i++)
+          glDisable (GL_CLIP_PLANE0+i);
+    }
+}
+
+void
+opengl_renderer::init_marker (const std::string& m, double size, float width)
+{
+  int vw[4];
+
+  glGetIntegerv (GL_VIEWPORT, vw);
+
+  glMatrixMode (GL_PROJECTION);
+  glPushMatrix ();
+  glLoadIdentity ();
+  glOrtho (0, vw[2], vw[3], 0, xZ1, xZ2);
+  glMatrixMode (GL_MODELVIEW);
+  glPushMatrix ();
+
+  set_clipping (false);
+  set_linewidth (width);
+
+  marker_id = make_marker_list (m, size, false);
+  filled_marker_id = make_marker_list (m, size, true);
+}
+
+void
+opengl_renderer::end_marker (void)
+{
+  glDeleteLists (marker_id, 1);
+  glDeleteLists (filled_marker_id, 1);
+
+  glMatrixMode (GL_MODELVIEW);
+  glPopMatrix ();
+  glMatrixMode (GL_PROJECTION);
+  glPopMatrix ();
+  set_linewidth (0.5f);
+}
+
+void
+opengl_renderer::draw_marker (double x, double y, double z,
+			      const Matrix& lc, const Matrix& fc)
+{
+  ColumnVector tmp = xform.transform (x, y, z, false);
+  
+  glLoadIdentity ();
+  glTranslated (tmp(0), tmp(1), -tmp(2));
+
+  if (fc.numel () > 0)
+    {
+      glColor3dv (fc.data ());
+      set_polygon_offset (true, 1.0);
+      glCallList (filled_marker_id);
+      set_polygon_offset (false);
+    }
+
+  if (lc.numel () > 0)
+    {
+      glColor3dv (lc.data ());
+      glCallList (marker_id);
+    }
+}
+
+unsigned int
+opengl_renderer::make_marker_list (const std::string& marker, double size,
+				   bool filled) const
+{
+  unsigned int ID = glGenLists (1);
+  double sz = size * backend.get_screen_resolution () / 72.0;
+
+  glNewList (ID, GL_COMPILE);
+
+  switch (marker[0])
+    {
+      case 's':
+        glBegin ((filled ? GL_POLYGON : GL_LINE_LOOP));
+        glVertex2d (-sz/2, -sz/2);
+        glVertex2d (-sz/2,  sz/2);
+        glVertex2d ( sz/2,  sz/2);
+        glVertex2d ( sz/2, -sz/2);
+        glEnd();
+        break;
+      case 'o':
+        {
+          double ang_step = M_PI / 5;
+
+          glBegin ((filled ? GL_POLYGON : GL_LINE_LOOP));
+          for (double ang = 0; ang < (2*M_PI); ang += ang_step)
+            glVertex2d (sz*cos(ang)/2, sz*sin(ang)/2);
+          glEnd ();
+        }
+        break;
+      case 'd':
+        glBegin ((filled ? GL_POLYGON : GL_LINE_LOOP));
+        glVertex2d (    0, -sz/2);
+        glVertex2d ( sz/2,     0);
+        glVertex2d (    0,  sz/2);
+        glVertex2d (-sz/2,     0);
+        glEnd();
+        break;
+      default:
+	warning ("opengl_renderer: unsupported marker `%s'",
+		 marker.c_str ());
+	break;
+    }
+
+  glEndList ();
+
+  return ID;
+}