In the original flightgear native/binary scenery terrain data format, we

used short's extensively to represent counts of objects (number of points,
number of texture coordinates, number of traingle strips, etc.) and we used
shorts to index into larger structures.  But this capped many of our structure
sizes to a maximum of 32768.

By switching to unsigned shorts in the future, we can double the maximum
object/index counts without losing anything.  This was a pretty major
oversight in our original specification.

I have bumped up the native object file version from 6 to 7 and added code
in the reader to maintain full backwards compatibilty with version 6
scenery files (i.e. the current 0.9.10 scenery release.)

Curt.

diff --git a/simgear/io/sg_binobj.cxx b/simgear/io/sg_binobj.cxx
index ee976d6832569cb5e2f6905b5654cf5a4bfea78c..f0af93b894c725f24b1e1a220f853328decdbd4c 100644 (file)
--- a/simgear/io/sg_binobj.cxx
+++ b/simgear/io/sg_binobj.cxx
@@ -364,18 +364,32 @@ bool SGBinObject::read_bin( const string& file ) {
 #endif
 
     // read number of top level objects
-    short nobjects;
-    sgReadShort( fp, &nobjects );
+    unsigned short nobjects;
+    if ( version >= 7 ) {
+        sgReadUShort( fp, &nobjects );
+    } else {
+        short tmp;
+        sgReadShort( fp, &tmp );
+        nobjects = tmp;
+    }
     // cout << "Total objects to read = " << nobjects << endl;
 
     // read in objects
     for ( i = 0; i < nobjects; ++i ) {
        // read object header
        char obj_type;
-       short nproperties, nelements;
+       unsigned short nproperties, nelements;
        sgReadChar( fp, &obj_type );
-       sgReadShort( fp, &nproperties );
-       sgReadShort( fp, &nelements );
+        if ( version >= 7 ) {
+            sgReadUShort( fp, &nproperties );
+            sgReadUShort( fp, &nelements );
+        } else {
+            short tmp;
+            sgReadShort( fp, &tmp );
+            nproperties = tmp;
+            sgReadShort( fp, &tmp );
+            nelements = tmp;
+        }
 
        // cout << "object " << i << " = " << (int)obj_type << " props = "
        //      << nproperties << " elements = " << nelements << endl;
@@ -649,7 +663,7 @@ bool SGBinObject::write_bin( const string& base, const string& name,
     string material;
     int start;
     int end;
-    short nobjects = 0;
+    unsigned short nobjects = 0;
     nobjects++;                        // for gbs
     nobjects++;                        // for vertices
     nobjects++;                        // for colors
@@ -657,7 +671,7 @@ bool SGBinObject::write_bin( const string& base, const string& name,
     nobjects++;                        // for texcoords
 
     // points
-    short npts = 0;
+    unsigned short npts = 0;
     start = 0; end = 1;
     while ( start < (int)pt_materials.size() ) {
        material = pt_materials[start];
@@ -671,7 +685,7 @@ bool SGBinObject::write_bin( const string& base, const string& name,
     nobjects += npts;
 
     // tris
-    short ntris = 0;
+    unsigned short ntris = 0;
     start = 0; end = 1;
     while ( start < (int)tri_materials.size() ) {
        material = tri_materials[start];
@@ -685,7 +699,7 @@ bool SGBinObject::write_bin( const string& base, const string& name,
     nobjects += ntris;
 
     // strips
-    short nstrips = 0;
+    unsigned short nstrips = 0;
     start = 0; end = 1;
     while ( start < (int)strip_materials.size() ) {
        material = strip_materials[start];
@@ -699,7 +713,7 @@ bool SGBinObject::write_bin( const string& base, const string& name,
     nobjects += nstrips;
 
     // fans
-    short nfans = 0;
+    unsigned short nfans = 0;
     start = 0; end = 1;
     while ( start < (int)fan_materials.size() ) {
        material = fan_materials[start];
@@ -713,12 +727,12 @@ bool SGBinObject::write_bin( const string& base, const string& name,
     nobjects += nfans;
 
     cout << "total top level objects = " << nobjects << endl;
-    sgWriteShort( fp, nobjects );
+    sgWriteUShort( fp, nobjects );
 
     // write bounding sphere
     sgWriteChar( fp, (char)SG_BOUNDING_SPHERE );        // type
-    sgWriteShort( fp, 0 );                             // nproperties
-    sgWriteShort( fp, 1 );                             // nelements
+    sgWriteUShort( fp, 0 );                            // nproperties
+    sgWriteUShort( fp, 1 );                            // nelements
 
     sgWriteUInt( fp, sizeof(double) * 3 + sizeof(float) ); // nbytes
     sgdVec3 center;
@@ -728,8 +742,8 @@ bool SGBinObject::write_bin( const string& base, const string& name,
 
     // dump vertex list
     sgWriteChar( fp, (char)SG_VERTEX_LIST );             // type
-    sgWriteShort( fp, 0 );                              // nproperties
-    sgWriteShort( fp, 1 );                              // nelements
+    sgWriteUShort( fp, 0 );                             // nproperties
+    sgWriteUShort( fp, 1 );                             // nelements
     sgWriteUInt( fp, wgs84_nodes.size() * sizeof(float) * 3 ); // nbytes
     for ( i = 0; i < (int)wgs84_nodes.size(); ++i ) {
         SGVec3f p = toVec3f(wgs84_nodes[i] - gbs_center);
@@ -738,8 +752,8 @@ bool SGBinObject::write_bin( const string& base, const string& name,
 
     // dump vertex color list
     sgWriteChar( fp, (char)SG_COLOR_LIST );             // type
-    sgWriteShort( fp, 0 );                              // nproperties
-    sgWriteShort( fp, 1 );                              // nelements
+    sgWriteUShort( fp, 0 );                             // nproperties
+    sgWriteUShort( fp, 1 );                             // nelements
     sgWriteUInt( fp, colors.size() * sizeof(float) * 4 ); // nbytes
     for ( i = 0; i < (int)colors.size(); ++i ) {
        sgWriteVec4( fp, colors[i].data() );
@@ -747,8 +761,8 @@ bool SGBinObject::write_bin( const string& base, const string& name,
 
     // dump vertex normal list
     sgWriteChar( fp, (char)SG_NORMAL_LIST );            // type
-    sgWriteShort( fp, 0 );                             // nproperties
-    sgWriteShort( fp, 1 );                             // nelements
+    sgWriteUShort( fp, 0 );                            // nproperties
+    sgWriteUShort( fp, 1 );                            // nelements
     sgWriteUInt( fp, normals.size() * 3 );              // nbytes
     char normal[3];
     for ( i = 0; i < (int)normals.size(); ++i ) {
@@ -761,8 +775,8 @@ bool SGBinObject::write_bin( const string& base, const string& name,
 
     // dump texture coordinates
     sgWriteChar( fp, (char)SG_TEXCOORD_LIST );          // type
-    sgWriteShort( fp, 0 );                             // nproperties
-    sgWriteShort( fp, 1 );                             // nelements
+    sgWriteUShort( fp, 0 );                            // nproperties
+    sgWriteUShort( fp, 1 );                            // nelements
     sgWriteUInt( fp, texcoords.size() * sizeof(float) * 2 ); // nbytes
     for ( i = 0; i < (int)texcoords.size(); ++i ) {
        sgWriteVec2( fp, texcoords[i].data() );
@@ -786,8 +800,8 @@ bool SGBinObject::write_bin( const string& base, const string& name,
 
            // write group headers
            sgWriteChar( fp, (char)SG_POINTS );          // type
-           sgWriteShort( fp, 2 );                       // nproperties
-           sgWriteShort( fp, end - start );             // nelements
+           sgWriteUShort( fp, 2 );                      // nproperties
+           sgWriteUShort( fp, end - start );             // nelements
 
            sgWriteChar( fp, (char)SG_MATERIAL );        // property
            sgWriteUInt( fp, material.length() );        // nbytes
@@ -806,19 +820,20 @@ bool SGBinObject::write_bin( const string& base, const string& name,
            // write strips
            for ( i = start; i < end; ++i ) {
                // nbytes
-               sgWriteUInt( fp, pts_v[i].size() * idx_size * sizeof(short) );
+               sgWriteUInt( fp, pts_v[i].size() * idx_size
+                                 * sizeof(unsigned short) );
                for ( j = 0; j < (int)pts_v[i].size(); ++j ) {
                    if ( pts_v.size() ) { 
-                       sgWriteShort( fp, (short)pts_v[i][j] );
+                       sgWriteUShort( fp, (unsigned short)pts_v[i][j] );
                    }
                    if ( pts_n.size() ) { 
-                       sgWriteShort( fp, (short)pts_n[i][j] );
+                       sgWriteUShort( fp, (unsigned short)pts_n[i][j] );
                    }
                    if ( pts_c.size() ) { 
-                       sgWriteShort( fp, (short)pts_c[i][j] );
+                       sgWriteUShort( fp, (unsigned short)pts_c[i][j] );
                    }
                    if ( pts_tc.size() ) { 
-                       sgWriteShort( fp, (short)pts_tc[i][j] );
+                       sgWriteUShort( fp, (unsigned short)pts_tc[i][j] );
                    }
                }
            }
@@ -847,8 +862,8 @@ bool SGBinObject::write_bin( const string& base, const string& name,
 
            // write group headers
            sgWriteChar( fp, (char)SG_TRIANGLE_FACES ); // type
-           sgWriteShort( fp, 2 );                      // nproperties
-           sgWriteShort( fp, 1 );                      // nelements
+           sgWriteUShort( fp, 2 );                     // nproperties
+           sgWriteUShort( fp, 1 );                      // nelements
 
            sgWriteChar( fp, (char)SG_MATERIAL );       // property
            sgWriteUInt( fp, material.length() );        // nbytes
@@ -865,22 +880,23 @@ bool SGBinObject::write_bin( const string& base, const string& name,
            sgWriteChar( fp, idx_mask );
 
            // nbytes
-           sgWriteUInt( fp, (end - start) * 3 * idx_size * sizeof(short) );
+           sgWriteUInt( fp, (end - start) * 3 * idx_size
+                             * sizeof(unsigned short) );
 
            // write group
            for ( i = start; i < end; ++i ) {
                for ( j = 0; j < 3; ++j ) {
                    if ( tris_v.size() ) {
-                       sgWriteShort( fp, (short)tris_v[i][j] );
+                       sgWriteUShort( fp, (unsigned short)tris_v[i][j] );
                    }
                    if ( tris_n.size() ) {
-                       sgWriteShort( fp, (short)tris_n[i][j] );
+                       sgWriteUShort( fp, (unsigned short)tris_n[i][j] );
                    }
                    if ( tris_c.size() ) {
-                       sgWriteShort( fp, (short)tris_c[i][j] );
+                       sgWriteUShort( fp, (unsigned short)tris_c[i][j] );
                    }
                    if ( tris_tc.size() ) {
-                       sgWriteShort( fp, (short)tris_tc[i][j] );
+                       sgWriteUShort( fp, (unsigned short)tris_tc[i][j] );
                    }
                }
            }
@@ -908,8 +924,8 @@ bool SGBinObject::write_bin( const string& base, const string& name,
 
            // write group headers
            sgWriteChar( fp, (char)SG_TRIANGLE_STRIPS ); // type
-           sgWriteShort( fp, 2 );                       // nproperties
-           sgWriteShort( fp, end - start );             // nelements
+           sgWriteUShort( fp, 2 );                      // nproperties
+           sgWriteUShort( fp, end - start );             // nelements
 
            sgWriteChar( fp, (char)SG_MATERIAL );        // property
            sgWriteUInt( fp, material.length() );        // nbytes
@@ -928,19 +944,20 @@ bool SGBinObject::write_bin( const string& base, const string& name,
            // write strips
            for ( i = start; i < end; ++i ) {
                // nbytes
-               sgWriteUInt( fp, strips_v[i].size() * idx_size * sizeof(short));
+               sgWriteUInt( fp, strips_v[i].size() * idx_size
+                                 * sizeof(unsigned short));
                for ( j = 0; j < (int)strips_v[i].size(); ++j ) {
                    if ( strips_v.size() ) { 
-                       sgWriteShort( fp, (short)strips_v[i][j] );
+                       sgWriteUShort( fp, (unsigned short)strips_v[i][j] );
                    }
                    if ( strips_n.size() ) { 
-                       sgWriteShort( fp, (short)strips_n[i][j] );
+                       sgWriteUShort( fp, (unsigned short)strips_n[i][j] );
                    }
                    if ( strips_c.size() ) { 
-                       sgWriteShort( fp, (short)strips_c[i][j] );
+                       sgWriteUShort( fp, (unsigned short)strips_c[i][j] );
                    }
                    if ( strips_tc.size() ) { 
-                       sgWriteShort( fp, (short)strips_tc[i][j] );
+                       sgWriteUShort( fp, (unsigned short)strips_tc[i][j] );
                    }
                }
            }
@@ -968,8 +985,8 @@ bool SGBinObject::write_bin( const string& base, const string& name,
 
            // write group headers
            sgWriteChar( fp, (char)SG_TRIANGLE_FANS );   // type
-           sgWriteShort( fp, 2 );                       // nproperties
-           sgWriteShort( fp, end - start );             // nelements
+           sgWriteUShort( fp, 2 );                      // nproperties
+           sgWriteUShort( fp, end - start );             // nelements
 
            sgWriteChar( fp, (char)SG_MATERIAL );       // property
            sgWriteUInt( fp, material.length() );        // nbytes
@@ -988,19 +1005,20 @@ bool SGBinObject::write_bin( const string& base, const string& name,
            // write fans
            for ( i = start; i < end; ++i ) {
                // nbytes
-               sgWriteUInt( fp, fans_v[i].size() * idx_size * sizeof(short) );
+               sgWriteUInt( fp, fans_v[i].size() * idx_size
+                                 * sizeof(unsigned short) );
                for ( j = 0; j < (int)fans_v[i].size(); ++j ) {
                    if ( fans_v.size() ) {
-                       sgWriteShort( fp, (short)fans_v[i][j] );
+                       sgWriteUShort( fp, (unsigned short)fans_v[i][j] );
                    }
                    if ( fans_n.size() ) {
-                       sgWriteShort( fp, (short)fans_n[i][j] );
+                       sgWriteUShort( fp, (unsigned short)fans_n[i][j] );
                    }
                    if ( fans_c.size() ) {
-                       sgWriteShort( fp, (short)fans_c[i][j] );
+                       sgWriteUShort( fp, (unsigned short)fans_c[i][j] );
                    }
                    if ( fans_tc.size() ) {
-                       sgWriteShort( fp, (short)fans_tc[i][j] );
+                       sgWriteUShort( fp, (unsigned short)fans_tc[i][j] );
                    }
                }
            }

diff --git a/simgear/io/sg_binobj.hxx b/simgear/io/sg_binobj.hxx
index cc4f9498308234cd990da4e616ca6c04db8cf101..d5c108fc15f805e978bf59ec298aa1a76299868e 100644 (file)
--- a/simgear/io/sg_binobj.hxx
+++ b/simgear/io/sg_binobj.hxx
@@ -74,9 +74,9 @@ typedef group_list::const_iterator const_group_list_iterator;
  *
  * - prop_typecode: material_name | ???
  *
- * - nelements: SHORT (Gives us 65536 which ought to be enough, right?)
+ * - nelements: USHORT (Gives us 65536 which ought to be enough, right?)
  *
- * - nproperties: SHORT
+ * - nproperties: USHORT
  *
  * - *_typecode: CHAR
  *