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
26 #include <simgear/compiler.h>
27 #include <simgear/constants.h>
28 #include <simgear/math/SGMath.hxx>
29 #include <simgear/math/SGGeometry.hxx>
32 class GroundCacheFillVisitor;
39 //////////////////////////////////////////////////////////////////////////
40 // Ground handling routines
41 //////////////////////////////////////////////////////////////////////////
43 // Prepare the ground cache for the wgs84 position pt_*.
44 // That is take all vertices in the ball with radius rad around the
45 // position given by the pt_* and store them in a local scene graph.
46 bool prepare_ground_cache(double ref_time, const SGVec3d& pt,
49 // Returns true if the cache is valid.
50 // Also the reference time, point and radius values where the cache
51 // is valid for are returned.
52 bool is_valid(double& ref_time, SGVec3d& pt, double& rad);
54 // Return the nearest catapult to the given point
55 // pt in wgs84 coordinates.
56 double get_cat(double t, const SGVec3d& pt,
57 SGVec3d end[2], SGVec3d vel[2]);
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 SGVec3d& pt, double max_altoff,
67 SGVec3d& contact, SGVec3d& normal, SGVec3d& vel,
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 SGVec3d pt[4]);
77 // Return the location and speed of the wire endpoints.
78 bool get_wire_ends(double t, SGVec3d end[2], SGVec3d vel[2]);
80 // Tell the cache code that it does no longer need to care for
81 // the wire end position.
82 void release_wire(void);
85 friend class GroundCacheFillVisitor;
88 Triangle() : material(0) {}
89 // The triangle we represent
92 // The linear and angular velocity.
95 SGVec3d rotation_pivot;
98 // the simgear material reference, contains friction coeficients ...
99 const SGMaterial* material;
106 SGVec3d rotation_pivot;
112 SGVec3d rotation_pivot;
117 // Approximate ground radius.
118 // In case the aircraft is too high above ground.
119 double ground_radius;
122 // the simgear material reference, contains friction coeficients ...
123 const SGMaterial* _material;
124 // The time reference for later call to intersection test routines.
125 // Is required since we will have moving triangles in carriers.
126 double cache_ref_time;
127 // The wire identifier to track.
130 // Containers which hold all the essential information about this cache.
131 std::vector<Triangle> triangles;
132 std::vector<Catapult> catapults;
133 std::vector<Wire> wires;
135 // The point and radius where the cache is built around.
136 // That are the arguments that were given to prepare_ground_cache.
137 SGVec3d reference_wgs84_point;
138 double reference_vehicle_radius;
143 // Helper class to hold some properties of the ground triangle.
144 struct GroundProperty {
145 GroundProperty() : type(0), material(0) {}
151 const SGMaterial* material;
154 static void velocityTransformTriangle(double dt, SGTriangled& dst,
155 SGSphered& sdst, const Triangle& src);