support for font textures. They are normal (but rather lenghty) <material>,

but contain <glyph> entries with <name>, <left> and <right>. The latter two
describe where in the texture a letter or symbol begins and where it ends.
(range 0-1). <xscale> defines a horizontal scaling factor.

simgear/scene/material/mat.cxx

@@ -159,6 +159,15 @@ SGMaterial::read_properties( const string &fg_root, const SGPropertyNode * props
     ((SGPropertyNode *)props)->getChildren("object-group");
   for (unsigned int i = 0; i < object_group_nodes.size(); i++)
     object_groups.push_back(new SGMatModelGroup(object_group_nodes[i]));
+
+  // handling of glyphs for taxi-/runway-signs
+  xscale = props->getDoubleValue("xscale", 1.0);
+  vector<SGPropertyNode_ptr> glyph_nodes = props->getChildren("glyph");
+  for (unsigned int i = 0; i < glyph_nodes.size(); i++) {
+    const char *name = glyph_nodes[i]->getStringValue("name");
+    if (name)
+      glyphs[name] = new SGMaterialGlyph(glyph_nodes[i]);
+  }
 }
 
 
@@ -176,6 +185,8 @@ SGMaterial::init ()
     ysize = 0;
     wrapu = true;
     wrapv = true;
+    xscale = 1;
+
     mipmap = true;
     light_coverage = 0.0;
     shininess = 1.0;
@@ -276,4 +287,17 @@ void SGMaterial::set_ssg_state( ssgSimpleState *s )
     _status.push_back( _internal_state( s, "", true ) );
 }
 
+
+
+////////////////////////////////////////////////////////////////////////
+// SGMaterialGlyph.
+////////////////////////////////////////////////////////////////////////
+
+SGMaterialGlyph::SGMaterialGlyph(SGPropertyNode *p) :
+    _left(p->getDoubleValue("left", 0.0)),
+    _right(p->getDoubleValue("right", 1.0))
+{
+}
+
+
 // end of mat.cxx

simgear/scene/material/mat.hxx

@@ -34,6 +34,7 @@
 
 #include STL_STRING      // Standard C++ string library
 #include <vector>
+#include <map>
 
 #include <plib/sg.h>
 #include <plib/ssg.h>
@@ -46,6 +47,10 @@
 
 SG_USING_STD(string);
 SG_USING_STD(vector);
+SG_USING_STD(map);
+
+
+class SGMaterialGlyph;
 
 
 /**
@@ -163,6 +168,19 @@ public:
     return object_groups[index];
   }
 
+  /**
+   * Get the horizontal scaling factor for runway/taxiway signs.
+   */
+  virtual inline double get_xscale() const { return xscale; }
+
+  /**
+   * Return pointer to glyph class, or 0 if it doesn't exist.
+   */
+  virtual SGMaterialGlyph * get_glyph (const string& name) const {
+    map<string, SGMaterialGlyph *>::const_iterator it = glyphs.find(name);
+    return it != glyphs.end() ? it->second : 0;
+  }
+
 protected:
 
 
@@ -216,6 +234,10 @@ private:
 
   vector<SGSharedPtr<SGMatModelGroup> > object_groups;
 
+  // taxiway-/runway-sign elements
+  double xscale;
+  map<string, SGMaterialGlyph *> glyphs;
+
 
   ////////////////////////////////////////////////////////////////////
   // Internal constructors and methods.
@@ -230,4 +252,17 @@ private:
 
 };
 
+
+class SGMaterialGlyph {
+public:
+  SGMaterialGlyph(SGPropertyNode *);
+  inline double get_left() const { return _left; }
+  inline double get_right() const { return _right; }
+  inline double get_width() const { return _right - _left; }
+
+protected:
+  double _left;
+  double _right;
+};
+
 #endif // _SG_MAT_HXX