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.
28 #include <simgear/sg_inlines.h>
29 #include <simgear/math/point3d.hxx>
30 #include <simgear/math/sg_geodesy.hxx>
31 #include <simgear/math/sg_random.h>
32 #include <simgear/scene/material/mat.hxx>
33 #include <simgear/scene/material/matmodel.hxx>
35 #include "userdata.hxx"
38 // the following are static values needed by the runtime object
39 // loader. However, the loading is done via a call back so these
40 // values cannot be passed as parameters. The calling application
41 // needs to call sgUserDataInit() with the appropriate values before
42 // building / drawing any scenery.
44 static bool _inited = false;
45 static SGModelLib *modellib = NULL;
46 static string model_root = "";
47 static SGPropertyNode *root_props = NULL;
48 static double sim_time_sec = 0.0;
50 void sgUserDataInit( SGModelLib *m, const string &r,
51 SGPropertyNode *p, double t ) {
60 static void random_pt_inside_tri( float *res,
61 float *n1, float *n2, float *n3 )
63 double a = sg_random();
64 double b = sg_random();
71 res[0] = n1[0]*a + n2[0]*b + n3[0]*c;
72 res[1] = n1[1]*a + n2[1]*b + n3[1]*c;
73 res[2] = n1[2]*a + n2[2]*b + n3[2]*c;
78 * Fill in a triangle with randomly-placed objects.
80 * This method is invoked by a callback when the triangle is in range
81 * but not yet populated.
85 void SGTriUserData::fill_in_triangle ()
87 // generate a repeatable random seed
90 int nObjects = object_group->get_object_count();
92 for (int i = 0; i < nObjects; i++) {
93 SGMatModel * object = object_group->get_object(i);
94 double num = area / object->get_coverage_m2();
96 // place an object each unit of area
98 add_object_to_triangle(object);
101 // for partial units of area, use a zombie door method to
102 // create the proper random chance of an object being created
105 if ( sg_random() <= num ) {
106 // a zombie made it through our door
107 add_object_to_triangle(object);
113 void SGTriUserData::add_object_to_triangle (SGMatModel * object)
115 // Set up the random heading if required.
117 if (object->get_heading_type() == SGMatModel::HEADING_RANDOM)
118 hdg_deg = sg_random() * 360;
121 makeWorldMatrix(mat, hdg_deg);
123 ssgTransform * pos = new ssgTransform;
124 pos->setTransform(mat);
125 // the parameters to get_random_model() are set in local static
126 // data via the ssgUserDataInit() function. This function must be
127 // called before any scenery is drawn.
128 pos->addKid( object->get_random_model( modellib, model_root,
129 root_props, sim_time_sec )
134 void SGTriUserData::makeWorldMatrix (sgMat4 mat, double hdg_deg )
137 mat[0][0] = leafData->sin_lat * leafData->cos_lon;
138 mat[0][1] = leafData->sin_lat * leafData->sin_lon;
139 mat[0][2] = -leafData->cos_lat;
142 mat[1][0] = -leafData->sin_lon;
143 mat[1][1] = leafData->cos_lon;
147 float sin_hdg = sin( hdg_deg * SGD_DEGREES_TO_RADIANS ) ;
148 float cos_hdg = cos( hdg_deg * SGD_DEGREES_TO_RADIANS ) ;
149 mat[0][0] = cos_hdg * leafData->sin_lat * leafData->cos_lon - sin_hdg * leafData->sin_lon;
150 mat[0][1] = cos_hdg * leafData->sin_lat * leafData->sin_lon + sin_hdg * leafData->cos_lon;
151 mat[0][2] = -cos_hdg * leafData->cos_lat;
154 mat[1][0] = -sin_hdg * leafData->sin_lat * leafData->cos_lon - cos_hdg * leafData->sin_lon;
155 mat[1][1] = -sin_hdg * leafData->sin_lat * leafData->sin_lon + cos_hdg * leafData->cos_lon;
156 mat[1][2] = sin_hdg * leafData->cos_lat;
160 mat[2][0] = leafData->cos_lat * leafData->cos_lon;
161 mat[2][1] = leafData->cos_lat * leafData->sin_lon;
162 mat[2][2] = leafData->sin_lat;
165 // translate to random point in triangle
167 random_pt_inside_tri(result, p1, p2, p3);
168 sgSubVec3(mat[3], result, center);
174 * SSG callback for an in-range triangle of randomly-placed objects.
176 * This pretraversal callback is attached to a branch that is traversed
177 * only when a triangle is in range. If the triangle is not currently
178 * populated with randomly-placed objects, this callback will populate
181 * @param entity The entity to which the callback is attached (not used).
182 * @param mask The entity's traversal mask (not used).
183 * @return Always 1, to allow traversal and culling to continue.
186 tri_in_range_callback (ssgEntity * entity, int mask)
188 SGTriUserData * data = (SGTriUserData *)entity->getUserData();
189 if (!data->is_filled_in) {
190 data->fill_in_triangle();
191 data->is_filled_in = true;
198 * SSG callback for an out-of-range triangle of randomly-placed objects.
200 * This pretraversal callback is attached to a branch that is traversed
201 * only when a triangle is out of range. If the triangle is currently
202 * populated with randomly-placed objects, the objects will be removed.
205 * @param entity The entity to which the callback is attached (not used).
206 * @param mask The entity's traversal mask (not used).
207 * @return Always 0, to prevent any further traversal or culling.
210 tri_out_of_range_callback (ssgEntity * entity, int mask)
212 SGTriUserData * data = (SGTriUserData *)entity->getUserData();
213 if (data->is_filled_in) {
214 data->branch->removeAllKids();
215 data->is_filled_in = false;
222 * Calculate the bounding radius of a triangle from its center.
224 * @param center The triangle center.
225 * @param p1 The first point in the triangle.
226 * @param p2 The second point in the triangle.
227 * @param p3 The third point in the triangle.
228 * @return The greatest distance any point lies from the center.
231 get_bounding_radius( sgVec3 center, float *p1, float *p2, float *p3)
233 return sqrt( SG_MAX3( sgDistanceSquaredVec3(center, p1),
234 sgDistanceSquaredVec3(center, p2),
235 sgDistanceSquaredVec3(center, p3) ) );
240 * Set up a triangle for randomly-placed objects.
242 * No objects will be added unless the triangle comes into range.
246 void SGLeafUserData::setup_triangle (int i )
249 leaf->getTriangle(i, &n1, &n2, &n3);
251 float * p1 = leaf->getVertex(n1);
252 float * p2 = leaf->getVertex(n2);
253 float * p3 = leaf->getVertex(n3);
255 // Set up a single center point for LOD
258 (p1[0] + p2[0] + p3[0]) / 3.0,
259 (p1[1] + p2[1] + p3[1]) / 3.0,
260 (p1[2] + p2[2] + p3[2]) / 3.0);
261 double area = sgTriArea(p1, p2, p3);
263 // maximum radius of an object from center.
264 double bounding_radius = get_bounding_radius(center, p1, p2, p3);
266 // Set up a transformation to the center
267 // point, so that everything else can
268 // be specified relative to it.
269 ssgTransform * location = new ssgTransform;
271 sgMakeTransMat4(TRANS, center);
272 location->setTransform(TRANS);
273 branch->addKid(location);
275 // Iterate through all the object types.
276 int num_groups = mat->get_object_group_count();
277 for (int j = 0; j < num_groups; j++) {
278 // Look up the random object.
279 SGMatModelGroup * group = mat->get_object_group(j);
281 // Set up the range selector for the entire
282 // triangle; note that we use the object
283 // range plus the bounding radius here, to
284 // allow for objects far from the center.
285 float ranges[] = { 0,
286 group->get_range_m() + bounding_radius,
288 ssgRangeSelector * lod = new ssgRangeSelector;
289 lod->setRanges(ranges, 3);
290 location->addKid(lod);
292 // Create the in-range and out-of-range
294 ssgBranch * in_range = new ssgBranch;
295 ssgBranch * out_of_range = new ssgBranch;
297 // Set up the user data for if/when
298 // the random objects in this triangle
300 SGTriUserData * data = new SGTriUserData;
301 data->is_filled_in = false;
305 sgCopyVec3 (data->center, center);
307 data->object_group = group;
308 data->branch = in_range;
309 data->leafData = this;
310 data->seed = (unsigned int)(p1[0] * j);
312 // Set up the in-range node.
313 in_range->setUserData(data);
314 in_range->setTravCallback(SSG_CALLBACK_PRETRAV,
315 tri_in_range_callback);
316 lod->addKid(in_range);
318 // Set up the out-of-range node.
319 out_of_range->setUserData(data);
320 out_of_range->setTravCallback(SSG_CALLBACK_PRETRAV,
321 tri_out_of_range_callback);
322 out_of_range->addKid(new SGDummyBSphereEntity(bounding_radius));
323 lod->addKid(out_of_range);