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flightgear/Simulator/Objects/obj.cxx
curt 29f6d05875 Initial revision
1999-04-05 21:32:32 +00:00

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// obj.cxx -- routines to handle "sorta" WaveFront .obj format files.
//
// Written by Curtis Olson, started October 1997.
//
// Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
//
// This program 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 2 of the
// License, or (at your option) any later version.
//
// This program 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 this program; if not, write to the Free Software
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
//
// $Id$
// (Log is kept at end of this file)
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#ifdef HAVE_WINDOWS_H
# include <windows.h>
#endif
#include <stdio.h>
#include <string.h>
#include <GL/glut.h>
#include <XGL/xgl.h>
// #if defined ( __sun__ )
// extern "C" void *memmove(void *, const void *, size_t);
// extern "C" void *memset(void *, int, size_t);
// #endif
#include <Include/compiler.h>
#include STL_STRING
#include <map> // STL
#include <ctype.h> // isdigit()
#include <Debug/logstream.hxx>
#include <Misc/fgstream.hxx>
#include <Include/fg_constants.h>
#include <Main/options.hxx>
#include <Math/mat3.h>
#include <Math/fg_random.h>
#include <Math/point3d.hxx>
#include <Math/polar3d.hxx>
#include <Misc/stopwatch.hxx>
#include <Scenery/tile.hxx>
#include "material.hxx"
#include "obj.hxx"
FG_USING_STD(string);
static double normals[MAX_NODES][3];
// given three points defining a triangle, calculate the normal
static void calc_normal(double p1[3], double p2[3],
double p3[3], double normal[3])
{
double v1[3], v2[3];
double temp;
v1[0] = p2[0] - p1[0]; v1[1] = p2[1] - p1[1]; v1[2] = p2[2] - p1[2];
v2[0] = p3[0] - p1[0]; v2[1] = p3[1] - p1[1]; v2[2] = p3[2] - p1[2];
MAT3cross_product(normal, v1, v2);
MAT3_NORMALIZE_VEC(normal,temp);
// fgPrintf( FG_TERRAIN, FG_DEBUG, " Normal = %.2f %.2f %.2f\n",
// normal[0], normal[1], normal[2]);
}
#define FG_TEX_CONSTANT 69.0
// Calculate texture coordinates for a given point.
static Point3D calc_tex_coords(double *node, const Point3D& ref) {
Point3D cp;
Point3D pp;
// double tmplon, tmplat;
// cout << "-> " << node[0] << " " << node[1] << " " << node[2] << endl;
// cout << "-> " << ref.x() << " " << ref.y() << " " << ref.z() << endl;
cp = Point3D( node[0] + ref.x(),
node[1] + ref.y(),
node[2] + ref.z() );
pp = fgCartToPolar3d(cp);
// tmplon = pp.lon() * RAD_TO_DEG;
// tmplat = pp.lat() * RAD_TO_DEG;
// cout << tmplon << " " << tmplat << endl;
pp.setx( fmod(RAD_TO_DEG * FG_TEX_CONSTANT * pp.x(), 11.0) );
pp.sety( fmod(RAD_TO_DEG * FG_TEX_CONSTANT * pp.y(), 11.0) );
if ( pp.x() < 0.0 ) {
pp.setx( pp.x() + 11.0 );
}
if ( pp.y() < 0.0 ) {
pp.sety( pp.y() + 11.0 );
}
// cout << pp << endl;
return(pp);
}
// Load a .obj file and build the GL fragment list
int fgObjLoad( const string& path, fgTILE *t) {
fgFRAGMENT fragment;
Point3D pp;
double approx_normal[3], normal[3] /*, scale = 0.0 */;
// double x, y, z, xmax, xmin, ymax, ymin, zmax, zmin;
// GLfloat sgenparams[] = { 1.0, 0.0, 0.0, 0.0 };
GLint display_list = 0;
int shading;
int in_fragment = 0, in_faces = 0, vncount;
int n1 = 0, n2 = 0, n3 = 0, n4 = 0;
int last1 = 0, last2 = 0, odd = 0;
double (*nodes)[3];
Point3D center;
// printf("loading %s\n", path.c_str() );
// Attempt to open "path.gz" or "path"
fg_gzifstream in( path );
if ( ! in ) {
FG_LOG( FG_TERRAIN, FG_ALERT, "Cannot open file: " << path );
return 0;
}
shading = current_options.get_shading();
in_fragment = 0;
t->ncount = 0;
vncount = 0;
t->bounding_radius = 0.0;
nodes = t->nodes;
center = t->center;
StopWatch stopwatch;
stopwatch.start();
// ignore initial comments and blank lines. (priming the pump)
// in >> skipcomment;
string line;
while ( ! in.eof() ) {
string token;
char c;
in >> skipws;
if ( in.get( c ) && c == '#' ) {
// process a comment line
// getline( in, line );
// cout << "comment = " << line << endl;
in >> token;
if ( token == "gbs" ) {
// reference point (center offset)
in >> t->center >> t->bounding_radius;
center = t->center;
// cout << "center = " << center
// << " radius = " << t->bounding_radius << endl;
} else if ( token == "bs" ) {
// reference point (center offset)
in >> fragment.center;
in >> fragment.bounding_radius;
// cout << "center = " << fragment.center
// << " radius = " << fragment.bounding_radius << endl;
} else if ( token == "usemtl" ) {
// material property specification
// series of individual triangles
if ( in_faces ) {
xglEnd();
}
// this also signals the start of a new fragment
if ( in_fragment ) {
// close out the previous structure and start the next
xglEndList();
// printf("xglEnd(); xglEndList();\n");
// update fragment
fragment.display_list = display_list;
// push this fragment onto the tile's object list
t->fragment_list.push_back(fragment);
} else {
in_fragment = 1;
}
// printf("start of fragment (usemtl)\n");
display_list = xglGenLists(1);
xglNewList(display_list, GL_COMPILE);
// printf("xglGenLists(); xglNewList();\n");
in_faces = 0;
// reset the existing face list
// printf("cleaning a fragment with %d faces\n",
// fragment.faces.size());
fragment.init();
// scan the material line
string material;
in >> material;
fragment.tile_ptr = t;
// find this material in the properties list
if ( ! material_mgr.find( material, fragment.material_ptr )) {
FG_LOG( FG_TERRAIN, FG_ALERT,
"Ack! unknown usemtl name = " << material
<< " in " << path );
}
// initialize the fragment transformation matrix
/*
for ( i = 0; i < 16; i++ ) {
fragment.matrix[i] = 0.0;
}
fragment.matrix[0] = fragment.matrix[5] =
fragment.matrix[10] = fragment.matrix[15] = 1.0;
*/
} else {
// unknown comment, just gobble the input untill the
// end of line
in >> skipeol;
}
} else {
in.putback( c );
in >> token;
// cout << "token = " << token << endl;
if ( token == "vn" ) {
// vertex normal
if ( vncount < MAX_NODES ) {
in >> normals[vncount][0]
>> normals[vncount][1]
>> normals[vncount][2];
vncount++;
} else {
FG_LOG( FG_TERRAIN, FG_ALERT,
"Read too many vertex normals ... dying :-(" );
exit(-1);
}
} else if ( token == "v" ) {
// node (vertex)
if ( t->ncount < MAX_NODES ) {
in >> t->nodes[t->ncount][0]
>> t->nodes[t->ncount][1]
>> t->nodes[t->ncount][2];
t->ncount++;
} else {
FG_LOG( FG_TERRAIN, FG_ALERT,
"Read too many nodes ... dying :-(");
exit(-1);
}
} else if ( token == "t" ) {
// start a new triangle strip
n1 = n2 = n3 = n4 = 0;
// fgPrintf( FG_TERRAIN, FG_DEBUG,
// " new tri strip = %s", line);
in >> n1 >> n2 >> n3;
fragment.add_face(n1, n2, n3);
// fgPrintf( FG_TERRAIN, FG_DEBUG, "(t) = ");
xglBegin(GL_TRIANGLE_STRIP);
// printf("xglBegin(tristrip) %d %d %d\n", n1, n2, n3);
odd = 1;
// scale = 1.0;
if ( shading ) {
// Shading model is "GL_SMOOTH" so use precalculated
// (averaged) normals
// MAT3_SCALE_VEC(normal, normals[n1], scale);
xglNormal3dv(normal);
pp = calc_tex_coords(nodes[n1], center);
xglTexCoord2f(pp.lon(), pp.lat());
xglVertex3dv(nodes[n1]);
// MAT3_SCALE_VEC(normal, normals[n2], scale);
xglNormal3dv(normal);
pp = calc_tex_coords(nodes[n2], center);
xglTexCoord2f(pp.lon(), pp.lat());
xglVertex3dv(nodes[n2]);
// MAT3_SCALE_VEC(normal, normals[n3], scale);
xglNormal3dv(normal);
pp = calc_tex_coords(nodes[n3], center);
xglTexCoord2f(pp.lon(), pp.lat());
xglVertex3dv(nodes[n3]);
} else {
// Shading model is "GL_FLAT" so calculate per face
// normals on the fly.
if ( odd ) {
calc_normal(nodes[n1], nodes[n2],
nodes[n3], approx_normal);
} else {
calc_normal(nodes[n2], nodes[n1],
nodes[n3], approx_normal);
}
// MAT3_SCALE_VEC(normal, approx_normal, scale);
xglNormal3dv(normal);
pp = calc_tex_coords(nodes[n1], center);
xglTexCoord2f(pp.lon(), pp.lat());
xglVertex3dv(nodes[n1]);
pp = calc_tex_coords(nodes[n2], center);
xglTexCoord2f(pp.lon(), pp.lat());
xglVertex3dv(nodes[n2]);
pp = calc_tex_coords(nodes[n3], center);
xglTexCoord2f(pp.lon(), pp.lat());
xglVertex3dv(nodes[n3]);
}
// printf("some normals, texcoords, and vertices\n");
odd = 1 - odd;
last1 = n2;
last2 = n3;
// There can be three or four values
char c;
while ( in.get(c) ) {
if ( c == '\n' ) {
break; // only the one
}
if ( isdigit(c) ){
in.putback(c);
in >> n4;
break;
}
}
if ( n4 > 0 ) {
fragment.add_face(n3, n2, n4);
if ( shading ) {
// Shading model is "GL_SMOOTH"
// MAT3_SCALE_VEC(normal, normals[n4], scale);
} else {
// Shading model is "GL_FLAT"
calc_normal(nodes[n3], nodes[n2], nodes[n4],
approx_normal);
// MAT3_SCALE_VEC(normal, approx_normal, scale);
}
xglNormal3dv(normal);
pp = calc_tex_coords(nodes[n4], center);
xglTexCoord2f(pp.lon(), pp.lat());
xglVertex3dv(nodes[n4]);
odd = 1 - odd;
last1 = n3;
last2 = n4;
// printf("a normal, texcoord, and vertex (4th)\n");
}
} else if ( token == "tf" ) {
// triangle fan
// fgPrintf( FG_TERRAIN, FG_DEBUG, "new fan");
xglBegin(GL_TRIANGLE_FAN);
in >> n1;
xglNormal3dv(normals[n1]);
pp = calc_tex_coords(nodes[n1], center);
xglTexCoord2f(pp.lon(), pp.lat());
xglVertex3dv(nodes[n1]);
in >> n2;
xglNormal3dv(normals[n2]);
pp = calc_tex_coords(nodes[n2], center);
xglTexCoord2f(pp.lon(), pp.lat());
xglVertex3dv(nodes[n2]);
// read all subsequent numbers until next thing isn't a number
while ( true ) {
in >> skipws;
char c;
in.get(c);
in.putback(c);
if ( ! isdigit(c) || in.eof() ) {
break;
}
in >> n3;
// cout << " triangle = "
// << n1 << "," << n2 << "," << n3
// << endl;
xglNormal3dv(normals[n3]);
pp = calc_tex_coords(nodes[n3], center);
xglTexCoord2f(pp.lon(), pp.lat());
xglVertex3dv(nodes[n3]);
fragment.add_face(n1, n2, n3);
n2 = n3;
}
xglEnd();
} else if ( token == "f" ) {
// unoptimized face
if ( !in_faces ) {
xglBegin(GL_TRIANGLES);
// printf("xglBegin(triangles)\n");
in_faces = 1;
}
// fgPrintf( FG_TERRAIN, FG_DEBUG, "new triangle = %s", line);*/
in >> n1 >> n2 >> n3;
fragment.add_face(n1, n2, n3);
// xglNormal3d(normals[n1][0], normals[n1][1], normals[n1][2]);
xglNormal3dv(normals[n1]);
pp = calc_tex_coords(nodes[n1], center);
xglTexCoord2f(pp.lon(), pp.lat());
xglVertex3dv(nodes[n1]);
xglNormal3dv(normals[n2]);
pp = calc_tex_coords(nodes[n2], center);
xglTexCoord2f(pp.lon(), pp.lat());
xglVertex3dv(nodes[n2]);
xglNormal3dv(normals[n3]);
pp = calc_tex_coords(nodes[n3], center);
xglTexCoord2f(pp.lon(), pp.lat());
xglVertex3dv(nodes[n3]);
// printf("some normals, texcoords, and vertices (tris)\n");
} else if ( token == "q" ) {
// continue a triangle strip
n1 = n2 = 0;
// fgPrintf( FG_TERRAIN, FG_DEBUG, "continued tri strip = %s ",
// line);
in >> n1;
// There can be one or two values
char c;
while ( in.get(c) ) {
if ( c == '\n' ) {
break; // only the one
}
if ( isdigit(c) ) {
in.putback(c);
in >> n2;
break;
}
}
// fgPrintf( FG_TERRAIN, FG_DEBUG, "read %d %d\n", n1, n2);
if ( odd ) {
fragment.add_face(last1, last2, n1);
} else {
fragment.add_face(last2, last1, n1);
}
if ( shading ) {
// Shading model is "GL_SMOOTH"
// MAT3_SCALE_VEC(normal, normals[n1], scale);
} else {
// Shading model is "GL_FLAT"
if ( odd ) {
calc_normal(nodes[last1], nodes[last2], nodes[n1],
approx_normal);
} else {
calc_normal(nodes[last2], nodes[last1], nodes[n1],
approx_normal);
}
// MAT3_SCALE_VEC(normal, approx_normal, scale);
}
xglNormal3dv(normal);
pp = calc_tex_coords(nodes[n1], center);
xglTexCoord2f(pp.lon(), pp.lat());
xglVertex3dv(nodes[n1]);
// printf("a normal, texcoord, and vertex (4th)\n");
odd = 1 - odd;
last1 = last2;
last2 = n1;
if ( n2 > 0 ) {
// fgPrintf( FG_TERRAIN, FG_DEBUG, " (cont)\n");
if ( odd ) {
fragment.add_face(last1, last2, n2);
} else {
fragment.add_face(last2, last1, n2);
}
if ( shading ) {
// Shading model is "GL_SMOOTH"
// MAT3_SCALE_VEC(normal, normals[n2], scale);
} else {
// Shading model is "GL_FLAT"
if ( odd ) {
calc_normal(nodes[last1], nodes[last2],
nodes[n2], approx_normal);
} else {
calc_normal(nodes[last2], nodes[last1],
nodes[n2], approx_normal);
}
// MAT3_SCALE_VEC(normal, approx_normal, scale);
}
xglNormal3dv(normal);
pp = calc_tex_coords(nodes[n2], center);
xglTexCoord2f(pp.lon(), pp.lat());
xglVertex3dv(nodes[n2]);
// printf("a normal, texcoord, and vertex (4th)\n");
odd = 1 -odd;
last1 = last2;
last2 = n2;
}
} else {
FG_LOG( FG_TERRAIN, FG_WARN, "Unknown token in "
<< path << " = " << token );
}
// eat white space before start of while loop so if we are
// done with useful input it is noticed before hand.
in >> skipws;
}
}
if ( in_fragment ) {
// close out the previous structure and start the next
xglEnd();
xglEndList();
// printf("xglEnd(); xglEndList();\n");
// update fragment
fragment.display_list = display_list;
// push this fragment onto the tile's object list
t->fragment_list.push_back(fragment);
}
#if 0
// Draw normal vectors (for visually verifying normals)
xglBegin(GL_LINES);
xglColor3f(0.0, 0.0, 0.0);
for ( i = 0; i < t->ncount; i++ ) {
xglVertex3d(t->nodes[i][0],
t->nodes[i][1] ,
t->nodes[i][2]);
xglVertex3d(t->nodes[i][0] + 500*normals[i][0],
t->nodes[i][1] + 500*normals[i][1],
t->nodes[i][2] + 500*normals[i][2]);
}
xglEnd();
#endif
stopwatch.stop();
FG_LOG( FG_TERRAIN, FG_INFO,
"Loaded " << path << " in "
<< stopwatch.elapsedSeconds() << " seconds" );
return 1;
}
// $Log$
// Revision 1.1 1999/04/05 21:32:49 curt
// Initial revision
//
// Revision 1.15 1999/03/31 13:25:58 curt
// Removed some debugging output.
//
// Revision 1.14 1999/03/30 23:48:24 curt
// modifications to obj loader to handle tri fans.
//
// Revision 1.13 1999/03/27 05:36:03 curt
// Alas, I have made non-backwardsly compatible changes to the scenery file
// format. Thus I have had to make the corresponding changes here in the
// file loader.
// Things that do not correspond the the .obj format are placed in comments.
//
// Revision 1.12 1999/03/02 01:03:25 curt
// Tweaks for building with native SGI compilers.
//
// Revision 1.11 1999/02/26 22:09:59 curt
// Added initial support for native SGI compilers.
//
// Revision 1.10 1998/11/06 21:18:18 curt
// Converted to new logstream debugging facility. This allows release
// builds with no messages at all (and no performance impact) by using
// the -DFG_NDEBUG flag.
//
// Revision 1.9 1998/11/06 14:47:06 curt
// Changes to track Bernie's updates to fgstream.
//
// Revision 1.8 1998/10/20 18:33:55 curt
// Tweaked texture coordinates, but we still have some problems. :-(
//
// Revision 1.7 1998/10/20 15:48:44 curt
// Removed an extraneous output message.
//
// Revision 1.6 1998/10/18 01:17:21 curt
// Point3D tweaks.
//
// Revision 1.5 1998/10/16 00:54:39 curt
// Converted to Point3D class.
//
// Revision 1.4 1998/09/15 01:35:07 curt
// cleaned up my fragment.num_faces hack :-) to use the STL (no need in
// duplicating work.)
// Tweaked fgTileMgrRender() do not calc tile matrix unless necessary.
// removed some unneeded stuff from fgTileMgrCurElev()
//
// Revision 1.3 1998/09/03 21:27:03 curt
// Fixed a serious bug caused by not-quite-correct comment/white space eating
// which resulted in mismatched glBegin() glEnd() pairs, incorrect display lists,
// and ugly display artifacts.
//
// Revision 1.2 1998/09/01 19:03:09 curt
// Changes contributed by Bernie Bright <bbright@c031.aone.net.au>
// - The new classes in libmisc.tgz define a stream interface into zlib.
// I've put these in a new directory, Lib/Misc. Feel free to rename it
// to something more appropriate. However you'll have to change the
// include directives in all the other files. Additionally you'll have
// add the library to Lib/Makefile.am and Simulator/Main/Makefile.am.
//
// The StopWatch class in Lib/Misc requires a HAVE_GETRUSAGE autoconf
// test so I've included the required changes in config.tgz.
//
// There are a fair few changes to Simulator/Objects as I've moved
// things around. Loading tiles is quicker but thats not where the delay
// is. Tile loading takes a few tenths of a second per file on a P200
// but it seems to be the post-processing that leads to a noticeable
// blip in framerate. I suppose its time to start profiling to see where
// the delays are.
//
// I've included a brief description of each archives contents.
//
// Lib/Misc/
// zfstream.cxx
// zfstream.hxx
// C++ stream interface into zlib.
// Taken from zlib-1.1.3/contrib/iostream/.
// Minor mods for STL compatibility.
// There's no copyright associated with these so I assume they're
// covered by zlib's.
//
// fgstream.cxx
// fgstream.hxx
// FlightGear input stream using gz_ifstream. Tries to open the
// given filename. If that fails then filename is examined and a
// ".gz" suffix is removed or appended and that file is opened.
//
// stopwatch.hxx
// A simple timer for benchmarking. Not used in production code.
// Taken from the Blitz++ project. Covered by GPL.
//
// strutils.cxx
// strutils.hxx
// Some simple string manipulation routines.
//
// Simulator/Airports/
// Load airports database using fgstream.
// Changed fgAIRPORTS to use set<> instead of map<>.
// Added bool fgAIRPORTS::search() as a neater way doing the lookup.
// Returns true if found.
//
// Simulator/Astro/
// Modified fgStarsInit() to load stars database using fgstream.
//
// Simulator/Objects/
// Modified fgObjLoad() to use fgstream.
// Modified fgMATERIAL_MGR::load_lib() to use fgstream.
// Many changes to fgMATERIAL.
// Some changes to fgFRAGMENT but I forget what!
//
// Revision 1.1 1998/08/25 16:51:25 curt
// Moved from ../Scenery
//
// Revision 1.23 1998/08/20 15:16:43 curt
// obj.cxx: use more explicit parenthases.
// texload.[ch]: use const in function definitions where appropriate.
//
// Revision 1.22 1998/08/20 15:12:03 curt
// Used a forward declaration of classes fgTILE and fgMATERIAL to eliminate
// the need for "void" pointers and casts.
// Quick hack to count the number of scenery polygons that are being drawn.
//
// Revision 1.21 1998/08/12 21:13:04 curt
// material.cxx: don't load textures if they are disabled
// obj.cxx: optimizations from Norman Vine
// tile.cxx: minor tweaks
// tile.hxx: addition of num_faces
// tilemgr.cxx: minor tweaks
//
// Revision 1.20 1998/07/24 21:42:07 curt
// material.cxx: whups, double method declaration with no definition.
// obj.cxx: tweaks to avoid errors in SGI's CC.
// tile.cxx: optimizations by Norman Vine.
// tilemgr.cxx: optimizations by Norman Vine.
//
// Revision 1.19 1998/07/13 21:01:58 curt
// Wrote access functions for current fgOPTIONS.
//
// Revision 1.18 1998/07/12 03:18:27 curt
// Added ground collision detection. This involved:
// - saving the entire vertex list for each tile with the tile records.
// - saving the face list for each fragment with the fragment records.
// - code to intersect the current vertical line with the proper face in
// an efficient manner as possible.
// Fixed a bug where the tiles weren't being shifted to "near" (0,0,0)
//
// Revision 1.17 1998/07/08 14:47:21 curt
// Fix GL_MODULATE vs. GL_DECAL problem introduced by splash screen.
// polare3d.h renamed to polar3d.hxx
// fg{Cartesian,Polar}Point3d consolodated.
// Added some initial support for calculating local current ground elevation.
//
// Revision 1.16 1998/07/06 21:34:33 curt
// Added using namespace std for compilers that support this.
//
// Revision 1.15 1998/07/04 00:54:28 curt
// Added automatic mipmap generation.
//
// When rendering fragments, use saved model view matrix from associated tile
// rather than recalculating it with push() translate() pop().
//
// Revision 1.14 1998/06/17 21:36:40 curt
// Load and manage multiple textures defined in the Materials library.
// Boost max material fagments for each material property to 800.
// Multiple texture support when rendering.
//
// Revision 1.13 1998/06/12 00:58:05 curt
// Build only static libraries.
// Declare memmove/memset for Sloaris.
//
// Revision 1.12 1998/06/08 17:57:54 curt
// Working first pass at material proporty sorting.
//
// Revision 1.11 1998/06/06 01:09:31 curt
// I goofed on the log message in the last commit ... now fixed.
//
// Revision 1.10 1998/06/06 01:07:17 curt
// Increased per material fragment list size from 100 to 400.
// Now correctly draw viewable fragments in per material order.
//
// Revision 1.9 1998/06/05 22:39:54 curt
// Working on sorting by, and rendering by material properties.
//
// Revision 1.8 1998/06/05 18:19:18 curt
// Recognize file, file.gz, and file.obj as scenery object files.
//
// Revision 1.7 1998/05/24 02:49:09 curt
// Implimented fragment level view frustum culling.
//
// Revision 1.6 1998/05/23 14:09:20 curt
// Added tile.cxx and tile.hxx.
// Working on rewriting the tile management system so a tile is just a list
// fragments, and the fragment record contains the display list for that
// fragment.
//
// Revision 1.5 1998/05/20 20:53:53 curt
// Moved global ref point and radius (bounding sphere info, and offset) to
// data file rather than calculating it on the fly.
// Fixed polygon winding problem in scenery generation stage rather than
// compensating for it on the fly.
// Made a fgTILECACHE class.
//
// Revision 1.4 1998/05/16 13:09:57 curt
// Beginning to add support for view frustum culling.
// Added some temporary code to calculate bouding radius, until the
// scenery generation tools and scenery can be updated.
//
// Revision 1.3 1998/05/03 00:48:01 curt
// Updated texture coordinate fmod() parameter.
//
// Revision 1.2 1998/05/02 01:52:14 curt
// Playing around with texture coordinates.
//
// Revision 1.1 1998/04/30 12:35:28 curt
// Added a command line rendering option specify smooth/flat shading.
//
// Revision 1.35 1998/04/28 21:43:26 curt
// Wrapped zlib calls up so we can conditionally comment out zlib support.
//
// Revision 1.34 1998/04/28 01:21:42 curt
// Tweaked texture parameter calculations to keep the number smaller. This
// avoids the "swimming" problem.
// Type-ified fgTIME and fgVIEW.
//
// Revision 1.33 1998/04/27 15:58:15 curt
// Screwing around with texture coordinate generation ... still needs work.
//
// Revision 1.32 1998/04/27 03:30:13 curt
// Minor transformation adjustments to try to keep scenery tiles closer to
// (0, 0, 0) GLfloats run out of precision at the distances we need to model
// the earth, but we can do a bunch of pre-transformations using double math
// and then cast to GLfloat once everything is close in where we have less
// precision problems.
//
// Revision 1.31 1998/04/25 15:09:57 curt
// Changed "r" to "rb" in gzopen() options. This fixes bad behavior in win32.
//
// Revision 1.30 1998/04/24 14:21:08 curt
// Added "file.obj.gz" support.
//
// Revision 1.29 1998/04/24 00:51:07 curt
// Wrapped "#include <config.h>" in "#ifdef HAVE_CONFIG_H"
// Tweaked the scenery file extentions to be "file.obj" (uncompressed)
// or "file.obz" (compressed.)
//
// Revision 1.28 1998/04/22 13:22:44 curt
// C++ - ifing the code a bit.
//
// Revision 1.27 1998/04/18 04:13:17 curt
// Added zlib on the fly decompression support for loading scenery objects.
//
// Revision 1.26 1998/04/03 22:11:36 curt
// Converting to Gnu autoconf system.
//
// Revision 1.25 1998/03/14 00:30:50 curt
// Beginning initial terrain texturing experiments.
//
// Revision 1.24 1998/02/09 21:30:18 curt
// Fixed a nagging problem with terrain tiles not "quite" matching up perfectly.
//
// Revision 1.23 1998/02/09 15:07:52 curt
// Minor tweaks.
//
// Revision 1.22 1998/02/01 03:39:54 curt
// Minor tweaks.
//
// Revision 1.21 1998/01/31 00:43:25 curt
// Added MetroWorks patches from Carmen Volpe.
//
// Revision 1.20 1998/01/29 00:51:39 curt
// First pass at tile cache, dynamic tile loading and tile unloading now works.
//
// Revision 1.19 1998/01/27 03:26:42 curt
// Playing with new fgPrintf command.
//
// Revision 1.18 1998/01/19 19:27:16 curt
// Merged in make system changes from Bob Kuehne <rpk@sgi.com>
// This should simplify things tremendously.
//
// Revision 1.17 1998/01/13 00:23:10 curt
// Initial changes to support loading and management of scenery tiles. Note,
// there's still a fair amount of work left to be done.
//
// Revision 1.16 1997/12/30 23:09:40 curt
// Worked on winding problem without luck, so back to calling glFrontFace()
// 3 times for each scenery area.
//
// Revision 1.15 1997/12/30 20:47:51 curt
// Integrated new event manager with subsystem initializations.
//
// Revision 1.14 1997/12/30 01:38:46 curt
// Switched back to per vertex normals and smooth shading for terrain.
//
// Revision 1.13 1997/12/18 23:32:36 curt
// First stab at sky dome actually starting to look reasonable. :-)
//
// Revision 1.12 1997/12/17 23:13:47 curt
// Began working on rendering the sky.
//
// Revision 1.11 1997/12/15 23:55:01 curt
// Add xgl wrappers for debugging.
// Generate terrain normals on the fly.
//
// Revision 1.10 1997/12/12 21:41:28 curt
// More light/material property tweaking ... still a ways off.
//
// Revision 1.9 1997/12/12 19:52:57 curt
// Working on lightling and material properties.
//
// Revision 1.8 1997/12/10 01:19:51 curt
// Tweaks for verion 0.15 release.
//
// Revision 1.7 1997/12/08 22:51:17 curt
// Enhanced to handle ccw and cw tri-stripe winding. This is a temporary
// admission of defeat. I will eventually go back and get all the stripes
// wound the same way (ccw).
//
// Revision 1.6 1997/11/25 19:25:35 curt
// Changes to integrate Durk's moon/sun code updates + clean up.
//
// Revision 1.5 1997/11/15 18:16:39 curt
// minor tweaks.
//
// Revision 1.4 1997/11/14 00:26:49 curt
// Transform scenery coordinates earlier in pipeline when scenery is being
// created, not when it is being loaded. Precalculate normals for each node
// as average of the normals of each containing polygon so Garoude shading is
// now supportable.
//
// Revision 1.3 1997/10/31 04:49:12 curt
// Tweaking vertex orders.
//
// Revision 1.2 1997/10/30 12:38:45 curt
// Working on new scenery subsystem.
//
// Revision 1.1 1997/10/28 21:14:54 curt
// Initial revision.
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