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obstacleAvoidance.cxx
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1/**
2 * PANDA 3D SOFTWARE
3 * Copyright (c) Carnegie Mellon University. All rights reserved.
4 *
5 * All use of this software is subject to the terms of the revised BSD
6 * license. You should have received a copy of this license along
7 * with this source code in a file named "LICENSE."
8 *
9 * @file obstacleAvoidance.cxx
10 * @author Deepak, John, Navin
11 * @date 2009-11-10
12 */
13
14#include "obstacleAvoidance.h"
15
16#include "aiWorld.h"
17
18ObstacleAvoidance::
19ObstacleAvoidance(AICharacter *ai_char, float feeler_length) {
20 _ai_char = ai_char;
21 _feeler = feeler_length;
22}
23
24ObstacleAvoidance::
25~ObstacleAvoidance() {
26}
27
28/**
29 * This function checks if an obstacle is near to the AICharacter and if an
30 * obstacle is detected returns true
31 */
32 bool ObstacleAvoidance::
33 obstacle_detection() {
34 // Calculate the volume of the AICharacter with respect to render
35 PT(BoundingVolume) np_bounds = _ai_char->get_node_path().get_bounds();
36 CPT(BoundingSphere) np_sphere = np_bounds->as_bounding_sphere();
37 LVecBase3 avoidance(0.0, 0.0, 0.0);
38 double distance = 0x7fff ;
39 double expanded_radius = 0;
40 LVecBase3 to_obstacle;
41 for(unsigned int i = 0; i < _ai_char->_world->_obstacles.size(); ++i) {
42 PT(BoundingVolume) bounds = _ai_char->_world->_obstacles[i].get_bounds();
43 CPT(BoundingSphere) bsphere = bounds->as_bounding_sphere();
44 LVecBase3 near_obstacle = _ai_char->_world->_obstacles[i].get_pos() - _ai_char->get_node_path().get_pos();
45 // Check if it's the nearest obstacle, If so initialize as the nearest
46 // obstacle
47 if((near_obstacle.length() < distance) && (_ai_char->_world->_obstacles[i].get_pos() != _ai_char->get_node_path().get_pos())) {
48 _nearest_obstacle = _ai_char->_world->_obstacles[i];
49 distance = near_obstacle.length();
50 expanded_radius = bsphere->get_radius() + np_sphere->get_radius();
51 }
52 }
53
54 LVecBase3 feeler = _feeler * _ai_char->get_char_render().get_relative_vector(_ai_char->get_node_path(), LVector3::forward());
55 feeler.normalize();
56 feeler *= (expanded_radius + np_sphere->get_radius()) ;
57 to_obstacle = _nearest_obstacle.get_pos() - _ai_char->get_node_path().get_pos();
58 LVector3 line_vector = _ai_char->get_char_render().get_relative_vector(_ai_char->get_node_path(), LVector3::forward());
59 LVecBase3 project = (to_obstacle.dot(line_vector) * line_vector) / line_vector.length_squared();
60 LVecBase3 perp = project - to_obstacle;
61
62 // If the nearest obstacle will collide with our AICharacter then send
63 // obstacle detection as true
64 if (_nearest_obstacle && (perp.length() < expanded_radius - np_sphere->get_radius()) && (project.length() < feeler.length())) {
65 return true;
66 }
67 return false;
68}
69
70/**
71 * This function activates obstacle_avoidance if a obstacle is detected
72 */
73 void ObstacleAvoidance::
74 obstacle_avoidance_activate() {
75 if (obstacle_detection()) {
76 _ai_char->_steering->turn_off("obstacle_avoidance_activate");
77 _ai_char->_steering->turn_on("obstacle_avoidance");
78 }
79}
80
81/**
82 * This function returns the force necessary by the AICharacter to avoid the
83 * nearest obstacle detected by obstacle_detection function NOTE : This
84 * assumes the obstacles are spherical
85 */
86LVecBase3 ObstacleAvoidance::
87 do_obstacle_avoidance() {
88 LVecBase3 offset = _ai_char->get_node_path().get_pos() - _nearest_obstacle.get_pos();
89 PT(BoundingVolume) bounds =_nearest_obstacle.get_bounds();
90 CPT(BoundingSphere) bsphere = bounds->as_bounding_sphere();
91 PT(BoundingVolume) np_bounds = _ai_char->get_node_path().get_bounds();
92 CPT(BoundingSphere) np_sphere = np_bounds->as_bounding_sphere();
93
94 if (obstacle_detection()) {
95 LVecBase3 direction = _ai_char->get_char_render().get_relative_vector(_ai_char->get_node_path(), LVector3::forward());
96 direction.normalize();
97 float forward_component = offset.dot(direction);
98 LVecBase3 projection = forward_component * direction;
99 LVecBase3 perpendicular_component = offset - projection;
100 double p = perpendicular_component.length();
101 perpendicular_component.normalize();
102 LVecBase3 avoidance = perpendicular_component;
103 // The more closer the obstacle, the more force it generates
104 avoidance = (avoidance * _ai_char->get_max_force() * _ai_char->_movt_force) / (p + 0.01);
105 return avoidance;
106 }
107 _ai_char->_steering->turn_on("obstacle_avoidance_activate");
108 _ai_char->_steering->turn_off("obstacle_avoidance");
109 return LVecBase3(0, 0, 0);
110}
aiWorld.h
PANDA 3D SOFTWARE Copyright (c) Carnegie Mellon University.
AICharacter
Definition aiCharacter.h:29
BoundingSphere
This defines a bounding sphere, consisting of a center and a radius.
Definition boundingSphere.h:25
BoundingVolume
This is an abstract class for any volume in any sense which can be said to define the locality of ref...
Definition boundingVolume.h:41
NodePath::get_bounds
PointerTo< BoundingVolume > get_bounds(Thread *current_thread=Thread::get_current_thread()) const
Returns a newly-allocated bounding volume containing the bottom node and all of its descendants.
Definition nodePath.cxx:5468
ObstacleAvoidance::obstacle_avoidance_activate
void obstacle_avoidance_activate()
This function activates obstacle_avoidance if a obstacle is detected.
Definition obstacleAvoidance.cxx:74
ObstacleAvoidance::obstacle_detection
bool obstacle_detection()
This function checks if an obstacle is near to the AICharacter and if an obstacle is detected returns...
Definition obstacleAvoidance.cxx:33
ObstacleAvoidance::do_obstacle_avoidance
LVecBase3 do_obstacle_avoidance()
This function returns the force necessary by the AICharacter to avoid the nearest obstacle detected b...
Definition obstacleAvoidance.cxx:87
obstacleAvoidance.h
PANDA 3D SOFTWARE Copyright (c) Carnegie Mellon University.