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 ),
81 fgFRAGMENT & fgFRAGMENT :: operator = ( const fgFRAGMENT & rhs )
83 if(!(this == &rhs )) {
85 bounding_radius = rhs.bounding_radius;
86 material_ptr = rhs.material_ptr;
87 tile_ptr = rhs.tile_ptr;
88 // display_list = rhs.display_list;
95 // Add a face to the face list
96 void fgFRAGMENT::add_face(int n1, int n2, int n3) {
103 faces.push_back(face);
108 // return the sign of a value
109 static int fg_sign( double x ) {
118 // return the minimum of the three values
119 static double fg_min( double a, double b, double c ) {
122 if (result > b) result = b;
123 if (result > c) result = c;
129 // return the maximum of the three values
130 static double fg_max( double a, double b, double c ) {
133 if (result < b) result = b;
134 if (result < c) result = c;
141 // return the minimum of the three values
142 static double fg_min3 (double a, double b, double c)
144 return (a > b ? FG_MIN (b, c) : FG_MIN (a, c));
148 // return the maximum of the three values
149 static double fg_max3 (double a, double b, double c)
151 return (a < b ? FG_MAX (b, c) : FG_MAX (a, c));
155 // test if line intesects with this fragment. p0 and p1 are the two
156 // line end points of the line. If side_flag is true, check to see
157 // that end points are on opposite sides of face. Returns 1 if it
158 // does, 0 otherwise. If it intesects, result is the point of
161 int fgFRAGMENT::intersect( fgPoint3d *end0, fgPoint3d *end1, int side_flag,
166 MAT3vec v1, v2, n, center;
167 double p1[3], p2[3], p3[3];
168 double x, y, z; // temporary holding spot for result
170 double x0, y0, z0, x1, y1, z1, a1, b1, c1;
172 double xmin, xmax, ymin, ymax, zmin, zmax;
173 double dx, dy, dz, min_dim, x2, y2, x3, y3, rx, ry;
175 list < fgFACE > :: iterator current;
176 list < fgFACE > :: iterator last;
178 // find the associated tile
179 t = (fgTILE *)tile_ptr;
181 // printf("Intersecting\n");
183 // traverse the face list for this fragment
184 current = faces.begin();
186 while ( current != last ) {
192 // get face vertex coordinates
193 center[0] = t->center.x;
194 center[1] = t->center.y;
195 center[2] = t->center.z;
197 MAT3_ADD_VEC(p1, t->nodes[face.n1], center);
198 MAT3_ADD_VEC(p2, t->nodes[face.n2], center);
199 MAT3_ADD_VEC(p3, t->nodes[face.n3], center);
201 // printf("point 1 = %.2f %.2f %.2f\n", p1[0], p1[1], p1[2]);
202 // printf("point 2 = %.2f %.2f %.2f\n", p2[0], p2[1], p2[2]);
203 // printf("point 3 = %.2f %.2f %.2f\n", p3[0], p3[1], p3[2]);
205 // calculate two edge vectors, and the face normal
206 MAT3_SUB_VEC(v1, p2, p1);
207 MAT3_SUB_VEC(v2, p3, p1);
208 MAT3cross_product(n, v1, v2);
210 // calculate the plane coefficients for the plane defined by
211 // this face. If n is the normal vector, n = (a, b, c) and p1
212 // is a point on the plane, p1 = (x0, y0, z0), then the
213 // equation of the line is a(x-x0) + b(y-y0) + c(z-z0) = 0
217 d = a * p1[0] + b * p1[1] + c * p1[2];
218 // printf("a, b, c, d = %.2f %.2f %.2f %.2f\n", a, b, c, d);
220 // printf("p1(d) = %.2f\n", a * p1[0] + b * p1[1] + c * p1[2]);
221 // printf("p2(d) = %.2f\n", a * p2[0] + b * p2[1] + c * p2[2]);
222 // printf("p3(d) = %.2f\n", a * p3[0] + b * p3[1] + c * p3[2]);
224 // calculate the line coefficients for the specified line
225 x0 = end0->x; x1 = end1->x;
226 y0 = end0->y; y1 = end1->y;
227 z0 = end0->z; z1 = end1->z;
229 if ( fabs(x1 - x0) > FG_EPSILON ) {
230 a1 = 1.0 / (x1 - x0);
232 // we got a big divide by zero problem here
238 // intersect the specified line with this plane
242 // printf("a = %.2f t1 = %.2f t2 = %.2f\n", a, t1, t2);
244 if ( fabs(a + t1 + t2) > FG_EPSILON ) {
245 x = (t1*x0 - b*y0 + t2*x0 - c*z0 + d) / (a + t1 + t2);
249 // printf("result(d) = %.2f\n", a * x + b * y + c * z);
251 // no intersection point
256 // check to see if end0 and end1 are on opposite sides of
258 if ( (x - x0) > FG_EPSILON ) {
262 } else if ( (y - y0) > FG_EPSILON ) {
266 } else if ( (z - z0) > FG_EPSILON ) {
271 // everything is too close together to tell the difference
272 // so the current intersection point should work as good
279 side1 = FG_SIGN (t1 - t2);
280 side2 = FG_SIGN (t1 - t3);
281 if ( side1 == side2 ) {
287 // check to see if intersection point is in the bounding
289 xmin = fg_min3 (p1[0], p2[0], p3[0]);
290 xmax = fg_max3 (p1[0], p2[0], p3[0]);
291 ymin = fg_min3 (p1[1], p2[1], p3[1]);
292 ymax = fg_max3 (p1[1], p2[1], p3[1]);
293 zmin = fg_min3 (p1[2], p2[2], p3[2]);
294 zmax = fg_max3 (p1[2], p2[2], p3[2]);
295 // printf("bounding cube = %.2f,%.2f,%.2f %.2f,%.2f,%.2f\n",
296 // xmin, ymin, zmin, xmax, ymax, zmax);
297 // punt if outside bouding cube
298 if ( x < (xmin = fg_min3 (p1[0], p2[0], p3[0])) ) {
300 } else if ( x > (xmax = fg_max3 (p1[0], p2[0], p3[0])) ) {
302 } else if ( y < (ymin = fg_min3 (p1[1], p2[1], p3[1])) ) {
304 } else if ( y > (ymax = fg_max3 (p1[1], p2[1], p3[1])) ) {
306 } else if ( z < (zmin = fg_min3 (p1[2], p2[2], p3[2])) ) {
308 } else if ( z > (zmax = fg_max3 (p1[2], p2[2], p3[2])) ) {
312 // (finally) check to see if the intersection point is
313 // actually inside this face
315 //first, drop the smallest dimension so we only have to work
320 min_dim = fg_min3 (dx, dy, dz);
321 if ( fabs(min_dim - dx) <= FG_EPSILON ) {
322 // x is the smallest dimension
331 } else if ( fabs(min_dim - dy) <= FG_EPSILON ) {
332 // y is the smallest dimension
341 } else if ( fabs(min_dim - dz) <= FG_EPSILON ) {
342 // z is the smallest dimension
352 // all dimensions are really small so lets call it close
353 // enough and return a successful match
360 // check if intersection point is on the same side of p1 <-> p2 as p3
361 t1 = (y1 - y2) / (x1 - x2);
362 side1 = FG_SIGN (t1 * ((x3) - x2) + y2 - (y3));
363 side2 = FG_SIGN (t1 * ((rx) - x2) + y2 - (ry));
364 if ( side1 != side2 ) {
365 // printf("failed side 1 check\n");
369 // check if intersection point is on correct side of p2 <-> p3 as p1
370 t1 = (y2 - y3) / (x2 - x3);
371 side1 = FG_SIGN (t1 * ((x1) - x3) + y3 - (y1));
372 side2 = FG_SIGN (t1 * ((rx) - x3) + y3 - (ry));
373 if ( side1 != side2 ) {
374 // printf("failed side 2 check\n");
378 // check if intersection point is on correct side of p1 <-> p3 as p2
379 t1 = (y1 - y3) / (x1 - x3);
380 side1 = FG_SIGN (t1 * ((x2) - x3) + y3 - (y2));
381 side2 = FG_SIGN (t1 * ((rx) - x3) + y3 - (ry));
382 if ( side1 != side2 ) {
383 // printf("failed side 3 check\n");
387 // printf( "intersection point = %.2f %.2f %.2f\n", x, y, z);
401 fgFRAGMENT::~fgFRAGMENT ( void ) {
402 // Step through the face list deleting the items until the list is
405 // printf("destructing a fragment with %d faces\n", faces.size());
407 while ( faces.size() ) {
408 // printf("emptying face list\n");
415 bool fgFRAGMENT :: operator == ( const fgFRAGMENT & rhs)
417 if(( center.x - rhs.center.x ) < FG_EPSILON) {
418 if(( center.y - rhs.center.y) < FG_EPSILON) {
419 if(( center.z - rhs.center.z) < FG_EPSILON) {
427 // comparison operator
428 bool fgFRAGMENT :: operator < ( const fgFRAGMENT &rhs)
430 // This is completely arbitrary. It satisfies RW's STL implementation
432 return bounding_radius < rhs.bounding_radius;
437 fgTILE::fgTILE ( void ) {
438 nodes = new double[MAX_NODES][3];
443 fgTILE::~fgTILE ( void ) {
449 // Revision 1.5 1998/07/24 21:42:08 curt
450 // material.cxx: whups, double method declaration with no definition.
451 // obj.cxx: tweaks to avoid errors in SGI's CC.
452 // tile.cxx: optimizations by Norman Vine.
453 // tilemgr.cxx: optimizations by Norman Vine.
455 // Revision 1.4 1998/07/22 21:41:42 curt
456 // Add basic fgFACE methods contributed by Charlie Hotchkiss.
457 // intersect optimization from Norman Vine.
459 // Revision 1.3 1998/07/16 17:34:24 curt
460 // Ground collision detection optimizations contributed by Norman Vine.
462 // Revision 1.2 1998/07/12 03:18:28 curt
463 // Added ground collision detection. This involved:
464 // - saving the entire vertex list for each tile with the tile records.
465 // - saving the face list for each fragment with the fragment records.
466 // - code to intersect the current vertical line with the proper face in
467 // an efficient manner as possible.
468 // Fixed a bug where the tiles weren't being shifted to "near" (0,0,0)
470 // Revision 1.1 1998/05/23 14:09:21 curt
471 // Added tile.cxx and tile.hxx.
472 // Working on rewriting the tile management system so a tile is just a list
473 // fragments, and the fragment record contains the display list for that fragment.