1 // tile.cxx -- routines to handle a scenery tile
3 // Written by Curtis Olson, started May 1998.
5 // Copyright (C) 1998 Curtis L. Olson - curt@infoplane.com
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>
32 // return the sign of a value
33 #define FG_SIGN( x ) ((x) < 0 ? -1 : 1)
35 // return min or max of two values
36 #define FG_MIN(A,B) ((A) < (B) ? (A) : (B))
37 #define FG_MAX(A,B) ((A) > (B) ? (A) : (B))
49 fgFACE :: fgFACE( const fgFACE & image ) :
50 n1( image.n1), n2( image.n2), n3( image.n3)
54 bool fgFACE :: operator < (const fgFACE & rhs )
56 return ( n1 < rhs.n1 ? true : false);
59 bool fgFACE :: operator == (const fgFACE & rhs )
61 return ((n1 == rhs.n1) && (n2 == rhs.n2) && ( n3 == rhs.n3));
66 fgFRAGMENT::fgFRAGMENT ( void ) {
71 fgFRAGMENT :: fgFRAGMENT ( const fgFRAGMENT & rhs ) :
72 center ( rhs.center ),
73 bounding_radius( rhs.bounding_radius ),
74 material_ptr ( rhs.material_ptr ),
75 tile_ptr ( rhs.tile_ptr ),
76 display_list ( rhs.display_list ),
78 num_faces ( rhs.num_faces )
82 fgFRAGMENT & fgFRAGMENT :: operator = ( const fgFRAGMENT & rhs )
84 if(!(this == &rhs )) {
86 bounding_radius = rhs.bounding_radius;
87 material_ptr = rhs.material_ptr;
88 tile_ptr = rhs.tile_ptr;
89 // display_list = rhs.display_list;
96 // Add a face to the face list
97 void fgFRAGMENT::add_face(int n1, int n2, int n3) {
104 faces.push_back(face);
110 // return the sign of a value
111 static int fg_sign( double x ) {
120 // return the minimum of the three values
121 static double fg_min( double a, double b, double c ) {
124 if (result > b) result = b;
125 if (result > c) result = c;
131 // return the maximum of the three values
132 static double fg_max( double a, double b, double c ) {
135 if (result < b) result = b;
136 if (result < c) result = c;
143 // return the minimum of the three values
144 static double fg_min3 (double a, double b, double c)
146 return (a > b ? FG_MIN (b, c) : FG_MIN (a, c));
150 // return the maximum of the three values
151 static double fg_max3 (double a, double b, double c)
153 return (a < b ? FG_MAX (b, c) : FG_MAX (a, c));
157 // test if line intesects with this fragment. p0 and p1 are the two
158 // line end points of the line. If side_flag is true, check to see
159 // that end points are on opposite sides of face. Returns 1 if it
160 // intersection found, 0 otherwise. If it intesects, result is the
161 // point of intersection
163 int fgFRAGMENT::intersect( fgPoint3d *end0, fgPoint3d *end1, int side_flag,
168 MAT3vec v1, v2, n, center;
169 double p1[3], p2[3], p3[3];
170 double x, y, z; // temporary holding spot for result
172 double x0, y0, z0, x1, y1, z1, a1, b1, c1;
174 double xmin, xmax, ymin, ymax, zmin, zmax;
175 double dx, dy, dz, min_dim, x2, y2, x3, y3, rx, ry;
177 list < fgFACE > :: iterator current;
178 list < fgFACE > :: iterator last;
180 // find the associated tile
183 // printf("Intersecting\n");
185 // traverse the face list for this fragment
186 current = faces.begin();
188 while ( current != last ) {
194 // get face vertex coordinates
195 center[0] = t->center.x;
196 center[1] = t->center.y;
197 center[2] = t->center.z;
199 MAT3_ADD_VEC(p1, t->nodes[face.n1], center);
200 MAT3_ADD_VEC(p2, t->nodes[face.n2], center);
201 MAT3_ADD_VEC(p3, t->nodes[face.n3], center);
203 // printf("point 1 = %.2f %.2f %.2f\n", p1[0], p1[1], p1[2]);
204 // printf("point 2 = %.2f %.2f %.2f\n", p2[0], p2[1], p2[2]);
205 // printf("point 3 = %.2f %.2f %.2f\n", p3[0], p3[1], p3[2]);
207 // calculate two edge vectors, and the face normal
208 MAT3_SUB_VEC(v1, p2, p1);
209 MAT3_SUB_VEC(v2, p3, p1);
210 MAT3cross_product(n, v1, v2);
212 // calculate the plane coefficients for the plane defined by
213 // this face. If n is the normal vector, n = (a, b, c) and p1
214 // is a point on the plane, p1 = (x0, y0, z0), then the
215 // equation of the line is a(x-x0) + b(y-y0) + c(z-z0) = 0
219 d = a * p1[0] + b * p1[1] + c * p1[2];
220 // printf("a, b, c, d = %.2f %.2f %.2f %.2f\n", a, b, c, d);
222 // printf("p1(d) = %.2f\n", a * p1[0] + b * p1[1] + c * p1[2]);
223 // printf("p2(d) = %.2f\n", a * p2[0] + b * p2[1] + c * p2[2]);
224 // printf("p3(d) = %.2f\n", a * p3[0] + b * p3[1] + c * p3[2]);
226 // calculate the line coefficients for the specified line
227 x0 = end0->x; x1 = end1->x;
228 y0 = end0->y; y1 = end1->y;
229 z0 = end0->z; z1 = end1->z;
231 if ( fabs(x1 - x0) > FG_EPSILON ) {
232 a1 = 1.0 / (x1 - x0);
234 // we got a big divide by zero problem here
240 // intersect the specified line with this plane
244 // printf("a = %.2f t1 = %.2f t2 = %.2f\n", a, t1, t2);
246 if ( fabs(a + t1 + t2) > FG_EPSILON ) {
247 x = (t1*x0 - b*y0 + t2*x0 - c*z0 + d) / (a + t1 + t2);
251 // printf("result(d) = %.2f\n", a * x + b * y + c * z);
253 // no intersection point
258 // check to see if end0 and end1 are on opposite sides of
260 if ( (x - x0) > FG_EPSILON ) {
264 } else if ( (y - y0) > FG_EPSILON ) {
268 } else if ( (z - z0) > FG_EPSILON ) {
273 // everything is too close together to tell the difference
274 // so the current intersection point should work as good
281 side1 = FG_SIGN (t1 - t2);
282 side2 = FG_SIGN (t1 - t3);
283 if ( side1 == side2 ) {
289 // check to see if intersection point is in the bounding
291 xmin = fg_min3 (p1[0], p2[0], p3[0]);
292 xmax = fg_max3 (p1[0], p2[0], p3[0]);
293 ymin = fg_min3 (p1[1], p2[1], p3[1]);
294 ymax = fg_max3 (p1[1], p2[1], p3[1]);
295 zmin = fg_min3 (p1[2], p2[2], p3[2]);
296 zmax = fg_max3 (p1[2], p2[2], p3[2]);
297 // printf("bounding cube = %.2f,%.2f,%.2f %.2f,%.2f,%.2f\n",
298 // xmin, ymin, zmin, xmax, ymax, zmax);
299 // punt if outside bouding cube
300 if ( x < (xmin = fg_min3 (p1[0], p2[0], p3[0])) ) {
302 } else if ( x > (xmax = fg_max3 (p1[0], p2[0], p3[0])) ) {
304 } else if ( y < (ymin = fg_min3 (p1[1], p2[1], p3[1])) ) {
306 } else if ( y > (ymax = fg_max3 (p1[1], p2[1], p3[1])) ) {
308 } else if ( z < (zmin = fg_min3 (p1[2], p2[2], p3[2])) ) {
310 } else if ( z > (zmax = fg_max3 (p1[2], p2[2], p3[2])) ) {
314 // (finally) check to see if the intersection point is
315 // actually inside this face
317 //first, drop the smallest dimension so we only have to work
322 min_dim = fg_min3 (dx, dy, dz);
323 if ( fabs(min_dim - dx) <= FG_EPSILON ) {
324 // x is the smallest dimension
333 } else if ( fabs(min_dim - dy) <= FG_EPSILON ) {
334 // y is the smallest dimension
343 } else if ( fabs(min_dim - dz) <= FG_EPSILON ) {
344 // z is the smallest dimension
354 // all dimensions are really small so lets call it close
355 // enough and return a successful match
362 // check if intersection point is on the same side of p1 <-> p2 as p3
363 t1 = (y1 - y2) / (x1 - x2);
364 side1 = FG_SIGN (t1 * ((x3) - x2) + y2 - (y3));
365 side2 = FG_SIGN (t1 * ((rx) - x2) + y2 - (ry));
366 if ( side1 != side2 ) {
367 // printf("failed side 1 check\n");
371 // check if intersection point is on correct side of p2 <-> p3 as p1
372 t1 = (y2 - y3) / (x2 - x3);
373 side1 = FG_SIGN (t1 * ((x1) - x3) + y3 - (y1));
374 side2 = FG_SIGN (t1 * ((rx) - x3) + y3 - (ry));
375 if ( side1 != side2 ) {
376 // printf("failed side 2 check\n");
380 // check if intersection point is on correct side of p1 <-> p3 as p2
381 t1 = (y1 - y3) / (x1 - x3);
382 side1 = FG_SIGN (t1 * ((x2) - x3) + y3 - (y2));
383 side2 = FG_SIGN (t1 * ((rx) - x3) + y3 - (ry));
384 if ( side1 != side2 ) {
385 // printf("failed side 3 check\n");
389 // printf( "intersection point = %.2f %.2f %.2f\n", x, y, z);
403 fgFRAGMENT::~fgFRAGMENT ( void ) {
404 // Step through the face list deleting the items until the list is
407 // printf("destructing a fragment with %d faces\n", faces.size());
409 while ( faces.size() ) {
410 // printf("emptying face list\n");
417 bool fgFRAGMENT :: operator == ( const fgFRAGMENT & rhs)
419 if(( center.x - rhs.center.x ) < FG_EPSILON) {
420 if(( center.y - rhs.center.y) < FG_EPSILON) {
421 if(( center.z - rhs.center.z) < FG_EPSILON) {
429 // comparison operator
430 bool fgFRAGMENT :: operator < ( const fgFRAGMENT &rhs)
432 // This is completely arbitrary. It satisfies RW's STL implementation
434 return bounding_radius < rhs.bounding_radius;
439 fgTILE::fgTILE ( void ) {
440 nodes = new double[MAX_NODES][3];
445 fgTILE::~fgTILE ( void ) {
451 // Revision 1.8 1998/08/22 14:49:58 curt
452 // Attempting to iron out seg faults and crashes.
453 // Did some shuffling to fix a initialization order problem between view
454 // position, scenery elevation.
456 // Revision 1.7 1998/08/20 15:12:05 curt
457 // Used a forward declaration of classes fgTILE and fgMATERIAL to eliminate
458 // the need for "void" pointers and casts.
459 // Quick hack to count the number of scenery polygons that are being drawn.
461 // Revision 1.6 1998/08/12 21:13:05 curt
462 // material.cxx: don't load textures if they are disabled
463 // obj.cxx: optimizations from Norman Vine
464 // tile.cxx: minor tweaks
465 // tile.hxx: addition of num_faces
466 // tilemgr.cxx: minor tweaks
468 // Revision 1.5 1998/07/24 21:42:08 curt
469 // material.cxx: whups, double method declaration with no definition.
470 // obj.cxx: tweaks to avoid errors in SGI's CC.
471 // tile.cxx: optimizations by Norman Vine.
472 // tilemgr.cxx: optimizations by Norman Vine.
474 // Revision 1.4 1998/07/22 21:41:42 curt
475 // Add basic fgFACE methods contributed by Charlie Hotchkiss.
476 // intersect optimization from Norman Vine.
478 // Revision 1.3 1998/07/16 17:34:24 curt
479 // Ground collision detection optimizations contributed by Norman Vine.
481 // Revision 1.2 1998/07/12 03:18:28 curt
482 // Added ground collision detection. This involved:
483 // - saving the entire vertex list for each tile with the tile records.
484 // - saving the face list for each fragment with the fragment records.
485 // - code to intersect the current vertical line with the proper face in
486 // an efficient manner as possible.
487 // Fixed a bug where the tiles weren't being shifted to "near" (0,0,0)
489 // Revision 1.1 1998/05/23 14:09:21 curt
490 // Added tile.cxx and tile.hxx.
491 // Working on rewriting the tile management system so a tile is just a list
492 // fragments, and the fragment record contains the display list for that fragment.