1 // fragment.cxx -- routines to handle "atomic" display objects
3 // Written by Curtis Olson, started August 1998.
5 // Copyright (C) 1998 Curtis L. Olson - curt@me.umn.edu
7 // This program is free software; you can redistribute it and/or
8 // modify it under the terms of the GNU General Public License as
9 // published by the Free Software Foundation; either version 2 of the
10 // License, or (at your option) any later version.
12 // This program is distributed in the hope that it will be useful, but
13 // WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 // General Public License for more details.
17 // You should have received a copy of the GNU General Public License
18 // along with this program; if not, write to the Free Software
19 // Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
22 // (Log is kept at end of this file)
25 #include <Include/fg_constants.h>
26 #include <Include/fg_types.h>
27 #include <Math/mat3.h>
28 #include <Scenery/tile.hxx>
30 #include "fragment.hxx"
34 inline const int FG_SIGN(const T& x) {
35 return x < T(0) ? -1 : 1;
39 inline const T& FG_MIN(const T& a, const T& b) {
44 inline const T& FG_MAX(const T& a, const T& b) {
48 // return the minimum of the three values
50 inline const T& fg_min3( const T& a, const T& b, const T& c)
52 return (a > b ? FG_MIN (b, c) : FG_MIN (a, c));
56 // return the maximum of the three values
58 inline const T& fg_max3 (const T& a, const T& b, const T& c)
60 return (a < b ? FG_MAX (b, c) : FG_MAX (a, c));
63 // Add a face to the face list
65 fgFRAGMENT::fgFRAGMENT ( const fgFRAGMENT & rhs ) :
66 center ( rhs.center ),
67 bounding_radius( rhs.bounding_radius ),
68 material_ptr ( rhs.material_ptr ),
69 tile_ptr ( rhs.tile_ptr ),
70 display_list ( rhs.display_list ),
72 num_faces ( rhs.num_faces )
76 fgFRAGMENT & fgFRAGMENT::operator = ( const fgFRAGMENT & rhs )
78 if(!(this == &rhs )) {
80 bounding_radius = rhs.bounding_radius;
81 material_ptr = rhs.material_ptr;
82 tile_ptr = rhs.tile_ptr;
83 // display_list = rhs.display_list;
90 // test if line intesects with this fragment. p0 and p1 are the two
91 // line end points of the line. If side_flag is true, check to see
92 // that end points are on opposite sides of face. Returns 1 if it
93 // intersection found, 0 otherwise. If it intesects, result is the
94 // point of intersection
96 int fgFRAGMENT::intersect( const fgPoint3d *end0,
97 const fgPoint3d *end1,
99 fgPoint3d *result) const
102 MAT3vec v1, v2, n, center;
103 double p1[3], p2[3], p3[3];
104 double x, y, z; // temporary holding spot for result
106 double x0, y0, z0, x1, y1, z1, a1, b1, c1;
108 double xmin, xmax, ymin, ymax, zmin, zmax;
109 double dx, dy, dz, min_dim, x2, y2, x3, y3, rx, ry;
112 // find the associated tile
115 // printf("Intersecting\n");
117 // traverse the face list for this fragment
118 const_iterator last = faces.end();
119 for ( const_iterator current = faces.begin(); current != last; ++current )
123 // get face vertex coordinates
124 center[0] = t->center.x;
125 center[1] = t->center.y;
126 center[2] = t->center.z;
128 MAT3_ADD_VEC(p1, t->nodes[(*current).n1], center);
129 MAT3_ADD_VEC(p2, t->nodes[(*current).n2], center);
130 MAT3_ADD_VEC(p3, t->nodes[(*current).n3], center);
132 // printf("point 1 = %.2f %.2f %.2f\n", p1[0], p1[1], p1[2]);
133 // printf("point 2 = %.2f %.2f %.2f\n", p2[0], p2[1], p2[2]);
134 // printf("point 3 = %.2f %.2f %.2f\n", p3[0], p3[1], p3[2]);
136 // calculate two edge vectors, and the face normal
137 MAT3_SUB_VEC(v1, p2, p1);
138 MAT3_SUB_VEC(v2, p3, p1);
139 MAT3cross_product(n, v1, v2);
141 // calculate the plane coefficients for the plane defined by
142 // this face. If n is the normal vector, n = (a, b, c) and p1
143 // is a point on the plane, p1 = (x0, y0, z0), then the
144 // equation of the line is a(x-x0) + b(y-y0) + c(z-z0) = 0
148 d = a * p1[0] + b * p1[1] + c * p1[2];
149 // printf("a, b, c, d = %.2f %.2f %.2f %.2f\n", a, b, c, d);
151 // printf("p1(d) = %.2f\n", a * p1[0] + b * p1[1] + c * p1[2]);
152 // printf("p2(d) = %.2f\n", a * p2[0] + b * p2[1] + c * p2[2]);
153 // printf("p3(d) = %.2f\n", a * p3[0] + b * p3[1] + c * p3[2]);
155 // calculate the line coefficients for the specified line
156 x0 = end0->x; x1 = end1->x;
157 y0 = end0->y; y1 = end1->y;
158 z0 = end0->z; z1 = end1->z;
160 if ( fabs(x1 - x0) > FG_EPSILON ) {
161 a1 = 1.0 / (x1 - x0);
163 // we got a big divide by zero problem here
169 // intersect the specified line with this plane
173 // printf("a = %.2f t1 = %.2f t2 = %.2f\n", a, t1, t2);
175 if ( fabs(a + t1 + t2) > FG_EPSILON ) {
176 x = (t1*x0 - b*y0 + t2*x0 - c*z0 + d) / (a + t1 + t2);
180 // printf("result(d) = %.2f\n", a * x + b * y + c * z);
182 // no intersection point
187 // check to see if end0 and end1 are on opposite sides of
189 if ( (x - x0) > FG_EPSILON ) {
193 } else if ( (y - y0) > FG_EPSILON ) {
197 } else if ( (z - z0) > FG_EPSILON ) {
202 // everything is too close together to tell the difference
203 // so the current intersection point should work as good
210 side1 = FG_SIGN (t1 - t2);
211 side2 = FG_SIGN (t1 - t3);
212 if ( side1 == side2 ) {
218 // check to see if intersection point is in the bounding
220 #ifdef XTRA_DEBUG_STUFF
221 xmin = fg_min3 (p1[0], p2[0], p3[0]);
222 xmax = fg_max3 (p1[0], p2[0], p3[0]);
223 ymin = fg_min3 (p1[1], p2[1], p3[1]);
224 ymax = fg_max3 (p1[1], p2[1], p3[1]);
225 zmin = fg_min3 (p1[2], p2[2], p3[2]);
226 zmax = fg_max3 (p1[2], p2[2], p3[2]);
227 printf("bounding cube = %.2f,%.2f,%.2f %.2f,%.2f,%.2f\n",
228 xmin, ymin, zmin, xmax, ymax, zmax);
230 // punt if outside bouding cube
231 if ( x < (xmin = fg_min3 (p1[0], p2[0], p3[0])) ) {
233 } else if ( x > (xmax = fg_max3 (p1[0], p2[0], p3[0])) ) {
235 } else if ( y < (ymin = fg_min3 (p1[1], p2[1], p3[1])) ) {
237 } else if ( y > (ymax = fg_max3 (p1[1], p2[1], p3[1])) ) {
239 } else if ( z < (zmin = fg_min3 (p1[2], p2[2], p3[2])) ) {
241 } else if ( z > (zmax = fg_max3 (p1[2], p2[2], p3[2])) ) {
245 // (finally) check to see if the intersection point is
246 // actually inside this face
248 //first, drop the smallest dimension so we only have to work
253 min_dim = fg_min3 (dx, dy, dz);
254 if ( fabs(min_dim - dx) <= FG_EPSILON ) {
255 // x is the smallest dimension
264 } else if ( fabs(min_dim - dy) <= FG_EPSILON ) {
265 // y is the smallest dimension
274 } else if ( fabs(min_dim - dz) <= FG_EPSILON ) {
275 // z is the smallest dimension
285 // all dimensions are really small so lets call it close
286 // enough and return a successful match
293 // check if intersection point is on the same side of p1 <-> p2 as p3
294 t1 = (y1 - y2) / (x1 - x2);
295 side1 = FG_SIGN (t1 * ((x3) - x2) + y2 - (y3));
296 side2 = FG_SIGN (t1 * ((rx) - x2) + y2 - (ry));
297 if ( side1 != side2 ) {
298 // printf("failed side 1 check\n");
302 // check if intersection point is on correct side of p2 <-> p3 as p1
303 t1 = (y2 - y3) / (x2 - x3);
304 side1 = FG_SIGN (t1 * ((x1) - x3) + y3 - (y1));
305 side2 = FG_SIGN (t1 * ((rx) - x3) + y3 - (ry));
306 if ( side1 != side2 ) {
307 // printf("failed side 2 check\n");
311 // check if intersection point is on correct side of p1 <-> p3 as p2
312 t1 = (y1 - y3) / (x1 - x3);
313 side1 = FG_SIGN (t1 * ((x2) - x3) + y3 - (y2));
314 side2 = FG_SIGN (t1 * ((rx) - x3) + y3 - (ry));
315 if ( side1 != side2 ) {
316 // printf("failed side 3 check\n");
320 // printf( "intersection point = %.2f %.2f %.2f\n", x, y, z);
333 // Revision 1.3 1998/09/08 21:40:42 curt
334 // Updates from Bernie Bright.
336 // Revision 1.2 1998/09/01 19:03:07 curt
337 // Changes contributed by Bernie Bright <bbright@c031.aone.net.au>
338 // - The new classes in libmisc.tgz define a stream interface into zlib.
339 // I've put these in a new directory, Lib/Misc. Feel free to rename it
340 // to something more appropriate. However you'll have to change the
341 // include directives in all the other files. Additionally you'll have
342 // add the library to Lib/Makefile.am and Simulator/Main/Makefile.am.
344 // The StopWatch class in Lib/Misc requires a HAVE_GETRUSAGE autoconf
345 // test so I've included the required changes in config.tgz.
347 // There are a fair few changes to Simulator/Objects as I've moved
348 // things around. Loading tiles is quicker but thats not where the delay
349 // is. Tile loading takes a few tenths of a second per file on a P200
350 // but it seems to be the post-processing that leads to a noticeable
351 // blip in framerate. I suppose its time to start profiling to see where
354 // I've included a brief description of each archives contents.
359 // C++ stream interface into zlib.
360 // Taken from zlib-1.1.3/contrib/iostream/.
361 // Minor mods for STL compatibility.
362 // There's no copyright associated with these so I assume they're
363 // covered by zlib's.
367 // FlightGear input stream using gz_ifstream. Tries to open the
368 // given filename. If that fails then filename is examined and a
369 // ".gz" suffix is removed or appended and that file is opened.
372 // A simple timer for benchmarking. Not used in production code.
373 // Taken from the Blitz++ project. Covered by GPL.
377 // Some simple string manipulation routines.
379 // Simulator/Airports/
380 // Load airports database using fgstream.
381 // Changed fgAIRPORTS to use set<> instead of map<>.
382 // Added bool fgAIRPORTS::search() as a neater way doing the lookup.
383 // Returns true if found.
386 // Modified fgStarsInit() to load stars database using fgstream.
388 // Simulator/Objects/
389 // Modified fgObjLoad() to use fgstream.
390 // Modified fgMATERIAL_MGR::load_lib() to use fgstream.
391 // Many changes to fgMATERIAL.
392 // Some changes to fgFRAGMENT but I forget what!
394 // Revision 1.1 1998/08/25 16:51:23 curt
395 // Moved from ../Scenery