1 // groundcache.hxx -- carries a small subset of the scenegraph near the vehicle
3 // Written by Mathias Froehlich, started Nov 2004.
5 // Copyright (C) 2004 Mathias Froehlich - Mathias.Froehlich@web.de
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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
23 #ifndef _GROUNDCACHE_HXX
24 #define _GROUNDCACHE_HXX
28 #include <simgear/compiler.h>
29 #include <simgear/constants.h>
38 //////////////////////////////////////////////////////////////////////////
39 // Ground handling routines
40 //////////////////////////////////////////////////////////////////////////
42 // Prepare the ground cache for the wgs84 position pt_*.
43 // That is take all vertices in the ball with radius rad around the
44 // position given by the pt_* and store them in a local scene graph.
45 bool prepare_ground_cache(double ref_time, const double pt[3],
48 // Returns true if the cache is valid.
49 // Also the reference time, point and radius values where the cache
50 // is valid for are returned.
51 bool is_valid(double *ref_time, double pt[3], double *rad);
54 // Return the nearest catapult to the given point
55 // pt in wgs84 coordinates.
56 double get_cat(double t, const double pt[3],
57 double end[2][3], double vel[2][3]);
60 // Return the altitude above ground below the wgs84 point pt
61 // Search for highest triangle not higher than pt + max_altoff.
62 // Return ground properties like the ground type, the maximum load
63 // this kind kind of ground can carry, the friction factor between
64 // 0 and 1 which can be used to model lower friction with wet runways
65 // and finally the altitude above ground.
66 bool get_agl(double t, const double pt[3], double max_altoff,
67 double contact[3], double normal[3], double vel[3],
68 int *type, const SGMaterial** material, double *agl);
70 // Return 1 if the hook intersects with a wire.
71 // That test is done by checking if the quad spanned by the points pt*
72 // intersects with the line representing the wire.
73 // If the wire is caught, the cache will trace this wires endpoints until
74 // the FDM calls release_wire().
75 bool caught_wire(double t, const double pt[4][3]);
77 // Return the location and speed of the wire endpoints.
78 bool get_wire_ends(double t, double end[2][3], double vel[2][3]);
80 // Tell the cache code that it does no longer need to care for
81 // the wire end position.
82 void release_wire(void);
86 Triangle() : material(0) {}
89 // The surface normal.
91 // The bounding shpere.
93 // The linear and angular velocity.
96 sgdVec3 rotation_pivot;
99 // the simgear material reference, contains friction coeficients ...
100 const SGMaterial* material;
107 sgdVec3 rotation_pivot;
113 sgdVec3 rotation_pivot;
118 // The center of the cache.
119 sgdVec3 cache_center;
120 // Approximate ground radius.
121 // In case the aircraft is too high above ground.
122 double ground_radius;
123 // The time reference for later call to intersection test routines.
124 // Is required since we will have moving triangles in carriers.
125 double cache_ref_time;
126 // The wire identifier to track.
129 // Containers which hold all the essential information about this cache.
130 std::vector<Triangle> triangles;
131 std::vector<Catapult> catapults;
132 std::vector<Wire> wires;
134 // The point and radius where the cache is built around.
135 // That are the arguments that were given to prepare_ground_cache.
136 sgdVec3 reference_wgs84_point;
137 double reference_vehicle_radius;
141 // Fills the environment cache with everything inside the sphere sp.
142 void cache_fill(ssgBranch *branch, sgdMat4 xform,
143 sgdSphere* sp, sgdVec3 down, sgdSphere* wsp);
145 // compute the ground property of this leaf.
146 void putSurfaceLeafIntoCache(const sgdSphere *sp, const sgdMat4 xform,
147 bool sphIsec, sgdVec3 down, ssgLeaf *l);
149 void putLineLeafIntoCache(const sgdSphere *wsp, const sgdMat4 xform,
152 // Helper class to hold some properties of the ground triangle.
153 struct GroundProperty {
154 GroundProperty() : type(0), material(0) {}
160 const SGMaterial* material;
163 // compute the ground property of this leaf.
164 static GroundProperty extractGroundProperty( ssgLeaf* leaf );
167 static void velocityTransformTriangle(double dt, Triangle& dst,
168 const Triangle& src);