1 // userdata.hxx -- two classes for populating ssg user data slots in association
2 // with our implimenation of random surface objects.
4 // Written by David Megginson, started December 2001.
6 // Copyright (C) 2001 - 2003 Curtis L. Olson - http://www.flightgear.org/~curt
8 // This program is free software; you can redistribute it and/or
9 // modify it under the terms of the GNU General Public License as
10 // published by the Free Software Foundation; either version 2 of the
11 // License, or (at your option) any later version.
13 // This program is distributed in the hope that it will be useful, but
14 // WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 // General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
25 # include <simgear_config.h>
31 #include <simgear/sg_inlines.h>
32 #include <simgear/math/point3d.hxx>
33 #include <simgear/math/sg_geodesy.hxx>
34 #include <simgear/math/sg_random.h>
35 #include <simgear/scene/material/mat.hxx>
36 #include <simgear/scene/material/matmodel.hxx>
38 #include "userdata.hxx"
41 // the following are static values needed by the runtime object
42 // loader. However, the loading is done via a call back so these
43 // values cannot be passed as parameters. The calling application
44 // needs to call sgUserDataInit() with the appropriate values before
45 // building / drawing any scenery.
47 static bool _inited = false;
48 static SGModelLib *modellib = NULL;
49 static string model_root = "";
50 static SGPropertyNode *root_props = NULL;
51 static double sim_time_sec = 0.0;
53 void sgUserDataInit( SGModelLib *m, const string &r,
54 SGPropertyNode *p, double t ) {
63 static void random_pt_inside_tri( float *res,
64 float *n1, float *n2, float *n3 )
66 double a = sg_random();
67 double b = sg_random();
74 res[0] = n1[0]*a + n2[0]*b + n3[0]*c;
75 res[1] = n1[1]*a + n2[1]*b + n3[1]*c;
76 res[2] = n1[2]*a + n2[2]*b + n3[2]*c;
81 * Fill in a triangle with randomly-placed objects.
83 * This method is invoked by a callback when the triangle is in range
84 * but not yet populated.
88 void SGTriUserData::fill_in_triangle ()
90 // generate a repeatable random seed
93 int nObjects = object_group->get_object_count();
95 for (int i = 0; i < nObjects; i++) {
96 SGMatModel * object = object_group->get_object(i);
97 double num = area / object->get_coverage_m2();
99 // place an object each unit of area
100 while ( num > 1.0 ) {
101 add_object_to_triangle(object);
104 // for partial units of area, use a zombie door method to
105 // create the proper random chance of an object being created
108 if ( sg_random() <= num ) {
109 // a zombie made it through our door
110 add_object_to_triangle(object);
116 void SGTriUserData::add_object_to_triangle (SGMatModel * object)
118 // Set up the random heading if required.
120 if (object->get_heading_type() == SGMatModel::HEADING_RANDOM)
121 hdg_deg = sg_random() * 360;
124 makeWorldMatrix(mat, hdg_deg);
126 ssgTransform * pos = new ssgTransform;
127 pos->setTransform(mat);
128 // the parameters to get_random_model() are set in local static
129 // data via the ssgUserDataInit() function. This function must be
130 // called before any scenery is drawn.
131 pos->addKid( object->get_random_model( modellib, model_root,
132 root_props, sim_time_sec )
137 void SGTriUserData::makeWorldMatrix (sgMat4 mat, double hdg_deg )
140 mat[0][0] = leafData->sin_lat * leafData->cos_lon;
141 mat[0][1] = leafData->sin_lat * leafData->sin_lon;
142 mat[0][2] = -leafData->cos_lat;
145 mat[1][0] = -leafData->sin_lon;
146 mat[1][1] = leafData->cos_lon;
150 float sin_hdg = sin( hdg_deg * SGD_DEGREES_TO_RADIANS ) ;
151 float cos_hdg = cos( hdg_deg * SGD_DEGREES_TO_RADIANS ) ;
152 mat[0][0] = cos_hdg * leafData->sin_lat * leafData->cos_lon - sin_hdg * leafData->sin_lon;
153 mat[0][1] = cos_hdg * leafData->sin_lat * leafData->sin_lon + sin_hdg * leafData->cos_lon;
154 mat[0][2] = -cos_hdg * leafData->cos_lat;
157 mat[1][0] = -sin_hdg * leafData->sin_lat * leafData->cos_lon - cos_hdg * leafData->sin_lon;
158 mat[1][1] = -sin_hdg * leafData->sin_lat * leafData->sin_lon + cos_hdg * leafData->cos_lon;
159 mat[1][2] = sin_hdg * leafData->cos_lat;
163 mat[2][0] = leafData->cos_lat * leafData->cos_lon;
164 mat[2][1] = leafData->cos_lat * leafData->sin_lon;
165 mat[2][2] = leafData->sin_lat;
168 // translate to random point in triangle
170 random_pt_inside_tri(result, p1, p2, p3);
171 sgSubVec3(mat[3], result, center);
177 * SSG callback for an in-range triangle of randomly-placed objects.
179 * This pretraversal callback is attached to a branch that is traversed
180 * only when a triangle is in range. If the triangle is not currently
181 * populated with randomly-placed objects, this callback will populate
184 * @param entity The entity to which the callback is attached (not used).
185 * @param mask The entity's traversal mask (not used).
186 * @return Always 1, to allow traversal and culling to continue.
189 tri_in_range_callback (ssgEntity * entity, int mask)
191 SGTriUserData * data = (SGTriUserData *)entity->getUserData();
192 if (!data->is_filled_in) {
193 data->fill_in_triangle();
194 data->is_filled_in = true;
201 * SSG callback for an out-of-range triangle of randomly-placed objects.
203 * This pretraversal callback is attached to a branch that is traversed
204 * only when a triangle is out of range. If the triangle is currently
205 * populated with randomly-placed objects, the objects will be removed.
208 * @param entity The entity to which the callback is attached (not used).
209 * @param mask The entity's traversal mask (not used).
210 * @return Always 0, to prevent any further traversal or culling.
213 tri_out_of_range_callback (ssgEntity * entity, int mask)
215 SGTriUserData * data = (SGTriUserData *)entity->getUserData();
216 if (data->is_filled_in) {
217 data->branch->removeAllKids();
218 data->is_filled_in = false;
225 * Calculate the bounding radius of a triangle from its center.
227 * @param center The triangle center.
228 * @param p1 The first point in the triangle.
229 * @param p2 The second point in the triangle.
230 * @param p3 The third point in the triangle.
231 * @return The greatest distance any point lies from the center.
234 get_bounding_radius( sgVec3 center, float *p1, float *p2, float *p3)
236 return sqrt( SG_MAX3( sgDistanceSquaredVec3(center, p1),
237 sgDistanceSquaredVec3(center, p2),
238 sgDistanceSquaredVec3(center, p3) ) );
243 * Set up a triangle for randomly-placed objects.
245 * No objects will be added unless the triangle comes into range.
249 void SGLeafUserData::setup_triangle (int i )
252 leaf->getTriangle(i, &n1, &n2, &n3);
254 float * p1 = leaf->getVertex(n1);
255 float * p2 = leaf->getVertex(n2);
256 float * p3 = leaf->getVertex(n3);
258 // Set up a single center point for LOD
261 (p1[0] + p2[0] + p3[0]) / 3.0,
262 (p1[1] + p2[1] + p3[1]) / 3.0,
263 (p1[2] + p2[2] + p3[2]) / 3.0);
264 double area = sgTriArea(p1, p2, p3);
266 // maximum radius of an object from center.
267 double bounding_radius = get_bounding_radius(center, p1, p2, p3);
269 // Set up a transformation to the center
270 // point, so that everything else can
271 // be specified relative to it.
272 ssgTransform * location = new ssgTransform;
274 sgMakeTransMat4(TRANS, center);
275 location->setTransform(TRANS);
276 branch->addKid(location);
278 // Iterate through all the object types.
279 int num_groups = mat->get_object_group_count();
280 for (int j = 0; j < num_groups; j++) {
281 // Look up the random object.
282 SGMatModelGroup * group = mat->get_object_group(j);
284 // Set up the range selector for the entire
285 // triangle; note that we use the object
286 // range plus the bounding radius here, to
287 // allow for objects far from the center.
288 float ranges[] = { 0,
289 group->get_range_m() + bounding_radius,
291 ssgRangeSelector * lod = new ssgRangeSelector;
292 lod->setRanges(ranges, 3);
293 location->addKid(lod);
295 // Create the in-range and out-of-range
297 ssgBranch * in_range = new ssgBranch;
298 ssgBranch * out_of_range = new ssgBranch;
300 // Set up the user data for if/when
301 // the random objects in this triangle
303 SGTriUserData * data = new SGTriUserData;
304 data->is_filled_in = false;
308 sgCopyVec3 (data->center, center);
310 data->object_group = group;
311 data->branch = in_range;
312 data->leafData = this;
313 data->seed = (unsigned int)(p1[0] * j);
315 // Set up the in-range node.
316 in_range->setUserData(data);
317 in_range->setTravCallback(SSG_CALLBACK_PRETRAV,
318 tri_in_range_callback);
319 lod->addKid(in_range);
321 // Set up the out-of-range node.
322 out_of_range->setUserData(data);
323 out_of_range->setTravCallback(SSG_CALLBACK_PRETRAV,
324 tri_out_of_range_callback);
325 out_of_range->addKid(new SGDummyBSphereEntity(bounding_radius));
326 lod->addKid(out_of_range);