+// 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 <string> // Standard C++ library
+#include <map> // STL
+
+#ifdef NEEDNAMESPACESTD
+using namespace std;
+#endif
+
+#include <Debug/fg_debug.h>
+#include <Include/fg_constants.h>
+#include <Include/fg_zlib.h>
+#include <Main/options.hxx>
+#include <Math/mat3.h>
+#include <Math/fg_random.h>
+#include <Math/polar3d.hxx>
+#include <Scenery/tile.hxx>
+
+#include "material.hxx"
+#include "obj.hxx"
+
+
+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 128.0
+
+
+// Calculate texture coordinates for a given point.
+fgPoint3d calc_tex_coords(double *node, fgPoint3d *ref) {
+ fgPoint3d cp;
+ fgPoint3d pp;
+
+ cp.x = node[0] + ref->x;
+ cp.y = node[1] + ref->y;
+ cp.z = node[2] + ref->z;
+
+ pp = fgCartToPolar3d(cp);
+
+ pp.lon = fmod(RAD_TO_DEG * FG_TEX_CONSTANT * pp.lon, 25.0);
+ pp.lat = fmod(RAD_TO_DEG * FG_TEX_CONSTANT * pp.lat, 25.0);
+
+ return(pp);
+}
+
+
+// Load a .obj file and build the GL fragment list
+int fgObjLoad(char *path, fgTILE *t) {
+ fgFRAGMENT fragment;
+ fgPoint3d pp;
+ char fgpath[256], line[256], material[256];
+ double approx_normal[3], normal[3], scale;
+ // double x, y, z, xmax, xmin, ymax, ymin, zmax, zmin;
+ // GLfloat sgenparams[] = { 1.0, 0.0, 0.0, 0.0 };
+ GLint display_list;
+ fgFile f;
+ int shading;
+ int in_fragment, in_faces, vncount, n1, n2, n3, n4;
+ int last1, last2, odd;
+ double (*nodes)[3];
+ fgPoint3d *center;
+
+ // First try "path.gz" (compressed format)
+ strcpy(fgpath, path);
+ strcat(fgpath, ".gz");
+ if ( (f = fgopen(fgpath, "rb")) == NULL ) {
+ // Next try "path" (uncompressed format)
+ strcpy(fgpath, path);
+ if ( (f = fgopen(fgpath, "rb")) == NULL ) {
+ // Next try "path.obj" (uncompressed format)
+ strcat(fgpath, ".gz");
+ if ( (f = fgopen(fgpath, "rb")) == NULL ) {
+ strcpy(fgpath, path);
+ fgPrintf( FG_TERRAIN, FG_ALERT,
+ "Cannot open file: %s\n", fgpath );
+ return(0);
+ }
+ }
+ }
+
+ shading = current_options.get_shading();
+
+ in_fragment = 0;
+ t->ncount = 1;
+ vncount = 1;
+ t->bounding_radius = 0.0;
+ nodes = t->nodes;
+ center = &t->center;
+
+ while ( fggets(f, line, 250) != NULL ) {
+ if ( line[0] == '#' ) {
+ // comment -- ignore
+ } else if ( line[0] == '\n' ) {
+ // empty line -- ignore
+ } else if ( strncmp(line, "gbs ", 4) == 0 ) {
+ // reference point (center offset)
+ sscanf(line, "gbs %lf %lf %lf %lf\n",
+ &t->center.x, &t->center.y, &t->center.z,
+ &t->bounding_radius);
+ } else if ( strncmp(line, "bs ", 3) == 0 ) {
+ // reference point (center offset)
+ sscanf(line, "bs %lf %lf %lf %lf\n",
+ &fragment.center.x, &fragment.center.y, &fragment.center.z,
+ &fragment.bounding_radius);
+ } else if ( strncmp(line, "v ", 2) == 0 ) {
+ // node (vertex)
+ if ( t->ncount < MAX_NODES ) {
+ // fgPrintf( FG_TERRAIN, FG_DEBUG, "vertex = %s", line);
+ sscanf(line, "v %lf %lf %lf\n",
+ &(t->nodes[t->ncount][0]), &(t->nodes[t->ncount][1]),
+ &(t->nodes[t->ncount][2]));
+
+ t->ncount++;
+
+ } else {
+ fgPrintf( FG_TERRAIN, FG_EXIT,
+ "Read too many nodes ... dying :-(\n");
+ }
+ } else if ( strncmp(line, "vn ", 3) == 0 ) {
+ // vertex normal
+ if ( vncount < MAX_NODES ) {
+ // fgPrintf( FG_TERRAIN, FG_DEBUG, "vertex normal = %s", line);
+ sscanf(line, "vn %lf %lf %lf\n",
+ &normals[vncount][0], &normals[vncount][1],
+ &normals[vncount][2]);
+ vncount++;
+ } else {
+ fgPrintf( FG_TERRAIN, FG_EXIT,
+ "Read too many vertex normals ... dying :-(\n");
+ }
+ } else if ( strncmp(line, "usemtl ", 7) == 0 ) {
+ // material property specification
+
+ // this also signals the start of a new fragment
+ if ( in_fragment ) {
+ // close out the previous structure and start the next
+ xglEnd();
+ xglEndList();
+
+ // 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;
+ }
+
+ display_list = xglGenLists(1);
+ xglNewList(display_list, GL_COMPILE);
+ in_faces = 0;
+
+ // reset the existing face list
+ // printf("cleaning a fragment with %d faces\n",
+ // fragment.faces.size());
+ while ( fragment.faces.size() ) {
+ // printf("emptying face list\n");
+ fragment.faces.pop_front();
+ }
+
+ // scan the material line
+ sscanf(line, "usemtl %s\n", material);
+
+ // give the fragment a pointer back to the tile
+ fragment.tile_ptr = t;
+
+ // find this material in the properties list
+ map < string, fgMATERIAL, less<string> > :: iterator myfind =
+ material_mgr.material_map.find(material);
+ if ( myfind == material_mgr.material_map.end() ) {
+ fgPrintf( FG_TERRAIN, FG_ALERT,
+ "Ack! unknown usemtl name = %s in %s\n",
+ material, path);
+ } else {
+ fragment.material_ptr = &((*myfind).second);
+ }
+
+ // 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;
+ */
+
+ // initialize fragment face counter
+ fragment.num_faces = 0;
+
+ } else if ( line[0] == 't' ) {
+ // start a new triangle strip
+
+ n1 = n2 = n3 = n4 = 0;
+
+ // fgPrintf( FG_TERRAIN, FG_DEBUG, " new tri strip = %s", line);
+ sscanf(line, "t %d %d %d %d\n", &n1, &n2, &n3, &n4);
+
+ fragment.add_face(n1, n2, n3);
+
+ // fgPrintf( FG_TERRAIN, FG_DEBUG, "(t) = ");
+
+ xglBegin(GL_TRIANGLE_STRIP);
+
+ 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);
+ // xglVertex3d(t->nodes[n1][0],t->nodes[n1][1],t->nodes[n1][2]);
+ xglVertex3dv(nodes[n1]);
+
+ MAT3_SCALE_VEC(normal, normals[n2], scale);
+ xglNormal3dv(normal);
+ pp = calc_tex_coords(nodes[n2], center);
+ xglTexCoord2f(pp.lon, pp.lat);
+ //xglVertex3d(t->nodes[n2][0],t->nodes[n2][1],t->nodes[n2][2]);
+ xglVertex3dv(nodes[n2]);
+
+ MAT3_SCALE_VEC(normal, normals[n3], scale);
+ xglNormal3dv(normal);
+ pp = calc_tex_coords(nodes[n3], center);
+ xglTexCoord2f(pp.lon, pp.lat);
+ // xglVertex3d(t->nodes[n3][0],t->nodes[n3][1],t->nodes[n3][2]);
+ 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);
+ // xglVertex3d(t->nodes[n1][0],t->nodes[n1][1],t->nodes[n1][2]);
+ xglVertex3dv(nodes[n1]);
+
+ pp = calc_tex_coords(nodes[n2], center);
+ xglTexCoord2f(pp.lon, pp.lat);
+ // xglVertex3d(t->nodes[n2][0],t->nodes[n2][1],t->nodes[n2][2]);
+ xglVertex3dv(nodes[n2]);
+
+ pp = calc_tex_coords(nodes[n3], center);
+ xglTexCoord2f(pp.lon, pp.lat);
+ // xglVertex3d(t->nodes[n3][0],t->nodes[n3][1],t->nodes[n3][2]);
+ xglVertex3dv(nodes[n3]);
+ }
+
+ odd = 1 - odd;
+ last1 = n2;
+ last2 = n3;
+
+ 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);
+ // xglVertex3d(t->nodes[n4][0],t->nodes[n4][1],t->nodes[n4][2]);
+ xglVertex3dv(nodes[n4]);
+
+ odd = 1 - odd;
+ last1 = n3;
+ last2 = n4;
+ }
+ } else if ( line[0] == 'f' ) {
+ // unoptimized face
+
+ if ( !in_faces ) {
+ xglBegin(GL_TRIANGLES);
+ in_faces = 1;
+ }
+
+ // fgPrintf( FG_TERRAIN, FG_DEBUG, "new triangle = %s", line);*/
+ sscanf(line, "f %d %d %d\n", &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);
+ // xglVertex3d(t->nodes[n1][0], t->nodes[n1][1], t->nodes[n1][2]);
+ xglVertex3dv(nodes[n1]);
+
+ // xglNormal3d(normals[n2][0], normals[n2][1], normals[n2][2]);
+ xglNormal3dv(normals[n2]);
+ pp = calc_tex_coords(nodes[n2], center);
+ xglTexCoord2f(pp.lon, pp.lat);
+ // xglVertex3d(t->nodes[n2][0], t->nodes[n2][1], t->nodes[n2][2]);
+ xglVertex3dv(nodes[n2]);
+
+ // xglNormal3d(normals[n3][0], normals[n3][1], normals[n3][2]);
+ xglNormal3dv(normals[n3]);
+ pp = calc_tex_coords(nodes[n3], center);
+ xglTexCoord2f(pp.lon, pp.lat);
+ // xglVertex3d(t->nodes[n3][0], t->nodes[n3][1], t->nodes[n3][2]);
+ xglVertex3dv(nodes[n3]);
+ } else if ( line[0] == 'q' ) {
+ // continue a triangle strip
+ n1 = n2 = 0;
+
+ // fgPrintf( FG_TERRAIN, FG_DEBUG, "continued tri strip = %s ",
+ // line);
+ sscanf(line, "q %d %d\n", &n1, &n2);
+ // 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);
+ xglNormal3dv(normal);
+ } 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);
+ // xglVertex3d(t->nodes[n1][0], t->nodes[n1][1], t->nodes[n1][2]);
+ xglVertex3dv(nodes[n1]);
+
+ 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);
+ xglNormal3dv(normal);
+ } 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);
+ // xglVertex3d(t->nodes[n2][0],t->nodes[n2][1],t->nodes[n2][2]);
+ xglVertex3dv(nodes[n2]);
+
+ odd = 1 -odd;
+ last1 = last2;
+ last2 = n2;
+ }
+ } else {
+ fgPrintf( FG_TERRAIN, FG_WARN, "Unknown line in %s = %s\n",
+ path, line);
+ }
+ }
+
+ if ( in_fragment ) {
+ // close out the previous structure and start the next
+ xglEnd();
+ xglEndList();
+
+ // update fragment
+ fragment.display_list = display_list;
+
+ // push this fragment onto the tile's object list
+ t->fragment_list.push_back(fragment);
+ }
+
+ // 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();
+ */
+
+ fgclose(f);
+
+ return(1);
+}
+
+
+// $Log$
+// 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.
+
+