From ed0acbad5ba11185f2a5f26d502bb088889cf21e Mon Sep 17 00:00:00 2001
From: curt <curt>
Date: Mon, 27 Apr 1998 03:30:13 +0000
Subject: [PATCH] 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.

---
 Scenery/obj.c       | 30 ++++++++++++++++++++++--------
 Scenery/tilemgr.cxx | 19 +++++++++++++------
 2 files changed, 35 insertions(+), 14 deletions(-)

diff --git a/Scenery/obj.c b/Scenery/obj.c
index fd6f807da..41d17ad54 100644
--- a/Scenery/obj.c
+++ b/Scenery/obj.c
@@ -95,7 +95,7 @@ float calc_lat(double x, double y, double z) {
 GLint fgObjLoad(char *path, struct fgCartesianPoint *ref, double *radius) {
     char gzpath[256], line[256], winding_str[256];
     double approx_normal[3], normal[3], scale;
-    double x, y, z, xmax, xmin, ymax, ymin, zmax, zmin;
+    // double x, y, z, xmax, xmin, ymax, ymin, zmax, zmin;
     GLfloat sgenparams[] = { 1.0, 0.0, 0.0, 0.0 };
     GLint tile;
     gzFile f;
@@ -143,16 +143,18 @@ GLint fgObjLoad(char *path, struct fgCartesianPoint *ref, double *radius) {
 	    /* comment -- ignore */
 	} else if ( line[0] == '\n' ) {
 	    /* empty line -- ignore */
+	} else if ( strncmp(line, "ref ", 4) == 0 ) {
+	    /* reference point (center offset) */
+	    sscanf(line, "ref %lf %lf %lf\n", &ref->x, &ref->y, &ref->z);
 	} else if ( strncmp(line, "v ", 2) == 0 ) {
 	    /* node (vertex) */
 	    if ( ncount < MAXNODES ) {
 		/* fgPrintf( FG_TERRAIN, FG_DEBUG, "vertex = %s", line); */
-		sscanf(line, "v %lf %lf %lf\n", &x, &y, &z);
-		nodes[ncount][0] = x;
-		nodes[ncount][1] = y;
-		nodes[ncount][2] = z;
+		sscanf(line, "v %lf %lf %lf\n", 
+		       &nodes[ncount][0], &nodes[ncount][1], &nodes[ncount][2]);
 
 		/* first time through set min's and max'es */
+		/*
 		if ( ncount == 1 ) {
 		    xmin = x;
 		    xmax = x;
@@ -161,14 +163,17 @@ GLint fgObjLoad(char *path, struct fgCartesianPoint *ref, double *radius) {
 		    zmin = z;
 		    zmax = z;
 		}
+		*/
     
 		/* keep track of min/max vertex values */
+		/*
 		if ( x < xmin ) xmin = x;
 		if ( x > xmax ) xmax = x;
 		if ( y < ymin ) ymin = y;
 		if ( y > ymax ) ymax = y;
 		if ( z < zmin ) zmin = z;
 		if ( z > zmax ) zmax = z;		
+		*/
 
 		ncount++;
 	    } else {
@@ -395,19 +400,28 @@ GLint fgObjLoad(char *path, struct fgCartesianPoint *ref, double *radius) {
 
     gzclose(f);
 
-    /* reference point is the "center" */
+    /* reference point is the "center" (now included in input file) */
+    /*
     ref->x = (xmin + xmax) / 2.0;
     ref->y = (ymin + ymax) / 2.0;
     ref->z = (zmin + zmax) / 2.0;
+    */
 
     return(tile);
 }
 
 
 /* $Log$
-/* Revision 1.31  1998/04/25 15:09:57  curt
-/* Changed "r" to "rb" in gzopen() options.  This fixes bad behavior in win32.
+/* Revision 1.32  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.
  *
diff --git a/Scenery/tilemgr.cxx b/Scenery/tilemgr.cxx
index d100a902e..daeeed7a4 100644
--- a/Scenery/tilemgr.cxx
+++ b/Scenery/tilemgr.cxx
@@ -208,11 +208,11 @@ void fgTileMgrRender( void ) {
 
 	if ( display_list >= 0 ) {
 	    xglPushMatrix();
-	    /* xglTranslatef(local_ref.x - scenery.center.x,
+	    xglTranslatef(local_ref.x - scenery.center.x,
 			  local_ref.y - scenery.center.y,
-			  local_ref.z - scenery.center.z); */
-	    xglTranslatef(-scenery.center.x, -scenery.center.y, 
-			  -scenery.center.z);
+			  local_ref.z - scenery.center.z);
+	    /* xglTranslatef(-scenery.center.x, -scenery.center.y, 
+			  -scenery.center.z); */
 	    xglCallList(display_list);
 	    xglPopMatrix();
 	}
@@ -221,9 +221,16 @@ void fgTileMgrRender( void ) {
 
 
 /* $Log$
-/* Revision 1.3  1998/04/25 22:06:32  curt
-/* Edited cvs log messages in source files ... bad bad bad!
+/* Revision 1.4  1998/04/27 03:30:14  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 1.3  1998/04/25 22:06:32  curt
+ * Edited cvs log messages in source files ... bad bad bad!
+ *
  * Revision 1.2  1998/04/24 00:51:09  curt
  * Wrapped "#include <config.h>" in "#ifdef HAVE_CONFIG_H"
  * Tweaked the scenery file extentions to be "file.obj" (uncompressed)
-- 
2.39.2