fly/flightgear
1
0
Fork 0
Code Activity
flightgear/Scenery/tile.cxx
curt 7e240adff1 Converted to Point3D class.
1998-10-16 00:51:46 +00:00

506 lines
13 KiB
C++
Raw Blame History

// tile.cxx -- routines to handle a scenery tile
//
// Written by Curtis Olson, started May 1998.
//
// Copyright (C) 1998 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)
#include <Include/fg_constants.h>
#include <Math/mat3.h>
#include "tile.hxx"
#if 0
// return the sign of a value
#define FG_SIGN( x ) ((x) < 0 ? -1 : 1)
// return min or max of two values
#define FG_MIN(A,B) ((A) < (B) ? (A) : (B))
#define FG_MAX(A,B) ((A) > (B) ? (A) : (B))
fgFACE :: fgFACE () :
n1(0), n2(0), n3(0)
{
}
fgFACE :: ~fgFACE()
{
}
fgFACE :: fgFACE( const fgFACE & image ) :
n1( image.n1), n2( image.n2), n3( image.n3)
{
}
bool fgFACE :: operator < (const fgFACE & rhs )
{
return ( n1 < rhs.n1 ? true : false);
}
bool fgFACE :: operator == (const fgFACE & rhs )
{
return ((n1 == rhs.n1) && (n2 == rhs.n2) && ( n3 == rhs.n3));
}
// Constructor
fgFRAGMENT::fgFRAGMENT ( void ) {
}
// Copy constructor
fgFRAGMENT :: fgFRAGMENT ( const fgFRAGMENT & rhs ) :
center ( rhs.center ),
bounding_radius( rhs.bounding_radius ),
material_ptr ( rhs.material_ptr ),
tile_ptr ( rhs.tile_ptr ),
display_list ( rhs.display_list ),
faces ( rhs.faces ),
num_faces ( rhs.num_faces )
{
}
fgFRAGMENT & fgFRAGMENT :: operator = ( const fgFRAGMENT & rhs )
{
if(!(this == &rhs )) {
center = rhs.center;
bounding_radius = rhs.bounding_radius;
material_ptr = rhs.material_ptr;
tile_ptr = rhs.tile_ptr;
// display_list = rhs.display_list;
faces = rhs.faces;
}
return *this;
}
// Add a face to the face list
void fgFRAGMENT::add_face(int n1, int n2, int n3) {
fgFACE face;
face.n1 = n1;
face.n2 = n2;
face.n3 = n3;
faces.push_back(face);
num_faces++;
}
/*
// return the sign of a value
static int fg_sign( double x ) {
if ( x >= 0 ) {
return(1);
} else {
return(-1);
}
}
// return the minimum of the three values
static double fg_min( double a, double b, double c ) {
double result;
result = a;
if (result > b) result = b;
if (result > c) result = c;
return(result);
}
// return the maximum of the three values
static double fg_max( double a, double b, double c ) {
double result;
result = a;
if (result < b) result = b;
if (result < c) result = c;
return(result);
}
*/
// return the minimum of the three values
static double fg_min3 (double a, double b, double c)
{
return (a > b ? FG_MIN (b, c) : FG_MIN (a, c));
}
// return the maximum of the three values
static double fg_max3 (double a, double b, double c)
{
return (a < b ? FG_MAX (b, c) : FG_MAX (a, c));
}
// test if line intesects with this fragment. p0 and p1 are the two
// line end points of the line. If side_flag is true, check to see
// that end points are on opposite sides of face. Returns 1 if it
// intersection found, 0 otherwise. If it intesects, result is the
// point of intersection
int fgFRAGMENT::intersect( const Point3D& end0, Point3D& end1, int side_flag,
Point3D& result)
{
fgTILE *t;
fgFACE face;
MAT3vec v1, v2, n, center;
double p1[3], p2[3], p3[3];
double x, y, z; // temporary holding spot for result
double a, b, c, d;
double x0, y0, z0, x1, y1, z1, a1, b1, c1;
double t1, t2, t3;
double xmin, xmax, ymin, ymax, zmin, zmax;
double dx, dy, dz, min_dim, x2, y2, x3, y3, rx, ry;
int side1, side2;
list < fgFACE > :: iterator current;
list < fgFACE > :: iterator last;
// find the associated tile
t = tile_ptr;
// printf("Intersecting\n");
// traverse the face list for this fragment
current = faces.begin();
last = faces.end();
while ( current != last ) {
face = *current;
current++;
// printf(".");
// get face vertex coordinates
center[0] = t->center.x;
center[1] = t->center.y;
center[2] = t->center.z;
MAT3_ADD_VEC(p1, t->nodes[face.n1], center);
MAT3_ADD_VEC(p2, t->nodes[face.n2], center);
MAT3_ADD_VEC(p3, t->nodes[face.n3], center);
// printf("point 1 = %.2f %.2f %.2f\n", p1[0], p1[1], p1[2]);
// printf("point 2 = %.2f %.2f %.2f\n", p2[0], p2[1], p2[2]);
// printf("point 3 = %.2f %.2f %.2f\n", p3[0], p3[1], p3[2]);
// calculate two edge vectors, and the face normal
MAT3_SUB_VEC(v1, p2, p1);
MAT3_SUB_VEC(v2, p3, p1);
MAT3cross_product(n, v1, v2);
// calculate the plane coefficients for the plane defined by
// this face. If n is the normal vector, n = (a, b, c) and p1
// is a point on the plane, p1 = (x0, y0, z0), then the
// equation of the line is a(x-x0) + b(y-y0) + c(z-z0) = 0
a = n[0];
b = n[1];
c = n[2];
d = a * p1[0] + b * p1[1] + c * p1[2];
// printf("a, b, c, d = %.2f %.2f %.2f %.2f\n", a, b, c, d);
// printf("p1(d) = %.2f\n", a * p1[0] + b * p1[1] + c * p1[2]);
// printf("p2(d) = %.2f\n", a * p2[0] + b * p2[1] + c * p2[2]);
// printf("p3(d) = %.2f\n", a * p3[0] + b * p3[1] + c * p3[2]);
// calculate the line coefficients for the specified line
x0 = end0.x(); x1 = end1.x();
y0 = end0.y(); y1 = end1.y();
z0 = end0.z(); z1 = end1.z();
if ( fabs(x1 - x0) > FG_EPSILON ) {
a1 = 1.0 / (x1 - x0);
} else {
// we got a big divide by zero problem here
a1 = 0.0;
}
b1 = y1 - y0;
c1 = z1 - z0;
// intersect the specified line with this plane
t1 = b * b1 * a1;
t2 = c * c1 * a1;
// printf("a = %.2f t1 = %.2f t2 = %.2f\n", a, t1, t2);
if ( fabs(a + t1 + t2) > FG_EPSILON ) {
x = (t1*x0 - b*y0 + t2*x0 - c*z0 + d) / (a + t1 + t2);
t3 = a1 * (x - x0);
y = b1 * t3 + y0;
z = c1 * t3 + z0;
// printf("result(d) = %.2f\n", a * x + b * y + c * z);
} else {
// no intersection point
continue;
}
if ( side_flag ) {
// check to see if end0 and end1 are on opposite sides of
// plane
if ( (x - x0) > FG_EPSILON ) {
t1 = x;
t2 = x0;
t3 = x1;
} else if ( (y - y0) > FG_EPSILON ) {
t1 = y;
t2 = y0;
t3 = y1;
} else if ( (z - z0) > FG_EPSILON ) {
t1 = z;
t2 = z0;
t3 = z1;
} else {
// everything is too close together to tell the difference
// so the current intersection point should work as good
// as any
result->x = x;
result->y = y;
result->z = z;
return(1);
}
side1 = FG_SIGN (t1 - t2);
side2 = FG_SIGN (t1 - t3);
if ( side1 == side2 ) {
// same side, punt
continue;
}
}
// check to see if intersection point is in the bounding
// cube of the face
#ifdef XTRA_DEBUG_STUFF
xmin = fg_min3 (p1[0], p2[0], p3[0]);
xmax = fg_max3 (p1[0], p2[0], p3[0]);
ymin = fg_min3 (p1[1], p2[1], p3[1]);
ymax = fg_max3 (p1[1], p2[1], p3[1]);
zmin = fg_min3 (p1[2], p2[2], p3[2]);
zmax = fg_max3 (p1[2], p2[2], p3[2]);
printf("bounding cube = %.2f,%.2f,%.2f %.2f,%.2f,%.2f\n",
xmin, ymin, zmin, xmax, ymax, zmax);
#endif
// punt if outside bouding cube
if ( x < (xmin = fg_min3 (p1[0], p2[0], p3[0])) ) {
continue;
} else if ( x > (xmax = fg_max3 (p1[0], p2[0], p3[0])) ) {
continue;
} else if ( y < (ymin = fg_min3 (p1[1], p2[1], p3[1])) ) {
continue;
} else if ( y > (ymax = fg_max3 (p1[1], p2[1], p3[1])) ) {
continue;
} else if ( z < (zmin = fg_min3 (p1[2], p2[2], p3[2])) ) {
continue;
} else if ( z > (zmax = fg_max3 (p1[2], p2[2], p3[2])) ) {
continue;
}
// (finally) check to see if the intersection point is
// actually inside this face
//first, drop the smallest dimension so we only have to work
//in 2d.
dx = xmax - xmin;
dy = ymax - ymin;
dz = zmax - zmin;
min_dim = fg_min3 (dx, dy, dz);
if ( fabs(min_dim - dx) <= FG_EPSILON ) {
// x is the smallest dimension
x1 = p1[1];
y1 = p1[2];
x2 = p2[1];
y2 = p2[2];
x3 = p3[1];
y3 = p3[2];
rx = y;
ry = z;
} else if ( fabs(min_dim - dy) <= FG_EPSILON ) {
// y is the smallest dimension
x1 = p1[0];
y1 = p1[2];
x2 = p2[0];
y2 = p2[2];
x3 = p3[0];
y3 = p3[2];
rx = x;
ry = z;
} else if ( fabs(min_dim - dz) <= FG_EPSILON ) {
// z is the smallest dimension
x1 = p1[0];
y1 = p1[1];
x2 = p2[0];
y2 = p2[1];
x3 = p3[0];
y3 = p3[1];
rx = x;
ry = y;
} else {
// all dimensions are really small so lets call it close
// enough and return a successful match
result->x = x;
result->y = y;
result->z = z;
return(1);
}
// check if intersection point is on the same side of p1 <-> p2 as p3
t1 = (y1 - y2) / (x1 - x2);
side1 = FG_SIGN (t1 * ((x3) - x2) + y2 - (y3));
side2 = FG_SIGN (t1 * ((rx) - x2) + y2 - (ry));
if ( side1 != side2 ) {
// printf("failed side 1 check\n");
continue;
}
// check if intersection point is on correct side of p2 <-> p3 as p1
t1 = (y2 - y3) / (x2 - x3);
side1 = FG_SIGN (t1 * ((x1) - x3) + y3 - (y1));
side2 = FG_SIGN (t1 * ((rx) - x3) + y3 - (ry));
if ( side1 != side2 ) {
// printf("failed side 2 check\n");
continue;
}
// check if intersection point is on correct side of p1 <-> p3 as p2
t1 = (y1 - y3) / (x1 - x3);
side1 = FG_SIGN (t1 * ((x2) - x3) + y3 - (y2));
side2 = FG_SIGN (t1 * ((rx) - x3) + y3 - (ry));
if ( side1 != side2 ) {
// printf("failed side 3 check\n");
continue;
}
// printf( "intersection point = %.2f %.2f %.2f\n", x, y, z);
result->x = x;
result->y = y;
result->z = z;
return(1);
}
// printf("\n");
return(0);
}
// Destructor
fgFRAGMENT::~fgFRAGMENT ( void ) {
// Step through the face list deleting the items until the list is
// empty
// printf("destructing a fragment with %d faces\n", faces.size());
faces.erase( faces.begin(), faces.end() );
}
// equality operator
bool fgFRAGMENT :: operator == ( const fgFRAGMENT & rhs)
{
if(( center.x - rhs.center.x ) < FG_EPSILON) {
if(( center.y - rhs.center.y) < FG_EPSILON) {
if(( center.z - rhs.center.z) < FG_EPSILON) {
return true;
}
}
}
return false;
}
// comparison operator
bool fgFRAGMENT :: operator < ( const fgFRAGMENT &rhs)
{
// This is completely arbitrary. It satisfies RW's STL implementation
return bounding_radius < rhs.bounding_radius;
}
#endif
// Constructor
fgTILE::fgTILE ( void ) {
nodes = new double[MAX_NODES][3];
}
// Destructor
fgTILE::~fgTILE ( void ) {
free(nodes);
}
// $Log$
// Revision 1.12 1998/10/16 00:55:45 curt
// Converted to Point3D class.
//
// Revision 1.11 1998/09/02 14:37:08 curt
// Use erase() instead of while ( size() ) pop_front();
//
// Revision 1.10 1998/08/25 16:52:42 curt
// material.cxx material.hxx obj.cxx obj.hxx texload.c texload.h moved to
// ../Objects
//
// Revision 1.9 1998/08/24 20:11:39 curt
// Tweaks ...
//
// Revision 1.8 1998/08/22 14:49:58 curt
// Attempting to iron out seg faults and crashes.
// Did some shuffling to fix a initialization order problem between view
// position, scenery elevation.
//
// Revision 1.7 1998/08/20 15:12:05 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 1.6 1998/08/12 21:13:05 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 1.5 1998/07/24 21:42:08 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 1.4 1998/07/22 21:41:42 curt
// Add basic fgFACE methods contributed by Charlie Hotchkiss.
// intersect optimization from Norman Vine.
//
// Revision 1.3 1998/07/16 17:34:24 curt
// Ground collision detection optimizations contributed by Norman Vine.
//
// Revision 1.2 1998/07/12 03:18:28 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 1.1 1998/05/23 14:09:21 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.
//
View git blame Copy permalink