src/ai/ai.cpp

   1 #include "AIController.hpp"
   2 #include "ChaseState.hpp"
   3 #include "FleeState.hpp"
   4 #include "IdleState.hpp"
   5 #include "RoamState.hpp"
   6
   7 #include "../geometry/distance.hpp"
   8 #include "../geometry/rotation.hpp"
   9 #include "../rand/GaloisLFSR.hpp"
  10 #include "../world/Entity.hpp"
  11 #include "../world/World.hpp"
  12 #include "../world/WorldCollision.hpp"
  13
  14 #include <cmath>
  15 #include <limits>
  16 #include <glm/glm.hpp>
  17
  18
  19 namespace blank {
  20
  21 namespace {
  22
  23 ChaseState chase;
  24 FleeState flee;
  25 IdleState idle;
  26 RoamState roam;
  27
  28 }
  29
  30 AIController::AIController(World &world, Entity &entity)
  31 : world(world)
  32 , state(&idle)
  33 , sight_dist(64.0f)
  34 , sight_angle(0.707f)
  35 , think_timer(0.5f)
  36 , decision_timer(1.0f) {
  37         think_timer.Start();
  38         state->Enter(*this, entity);
  39 }
  40
  41 AIController::~AIController() {
  42         // ignore this for now
  43         // state->Exit(*this, entity);
  44 }
  45
  46 void AIController::SetState(const AIState &s, Entity &entity) {
  47         state->Exit(*this, entity);
  48         state = &s;
  49         state->Enter(*this, entity);
  50 }
  51
  52 void AIController::Update(Entity &e, float dt) {
  53         think_timer.Update(dt);
  54         decision_timer.Update(dt);
  55         state->Update(*this, e, dt);
  56
  57         if (e.Moving()) {
  58                 // orient head towards heading
  59                 glm::vec3 heading(e.Heading());
  60                 // only half pitch, so we don't crane our neck
  61                 float tgt_pitch = std::atan(heading.y / length(glm::vec2(heading.x, heading.z))) * 0.5f;
  62                 // always look straight ahead
  63                 // maybe look at the pursuit target if there is one
  64                 float tgt_yaw = 0.0f;
  65                 e.SetHead(tgt_pitch, tgt_yaw);
  66                 e.OrientBody(dt);
  67         }
  68 }
  69
  70 Player *AIController::ClosestVisiblePlayer(const Entity &e) noexcept {
  71         Player *target = nullptr;
  72         float distance = sight_dist;
  73         const glm::ivec3 &reference(e.ChunkCoords());
  74         Ray aim(e.Aim(reference));
  75         for (Player &p : world.Players()) {
  76                 const Entity &pe = p.GetEntity();
  77
  78                 // distance test
  79                 const glm::vec3 diff(pe.AbsoluteDifference(e));
  80                 float dist = length(diff);
  81                 if (dist > distance) continue;
  82
  83                 // FOV test, 45° in each direction
  84                 if (dot(diff / dist, aim.dir) < sight_angle) {
  85                         continue;
  86                 }
  87
  88                 // LOS test, assumes all entities are see-through
  89                 WorldCollision col;
  90                 if (world.Intersection(aim, reference, col) && col.depth < dist) {
  91                         continue;
  92                 }
  93
  94                 // we got a match
  95                 target = &p;
  96                 distance = dist;
  97         }
  98         return target;
  99 }
 100
 101 bool AIController::LineOfSight(const Entity &from, const Entity &to) const noexcept {
 102         const glm::ivec3 &reference(from.ChunkCoords());
 103         Ray aim(from.Aim(reference));
 104         const glm::vec3 diff(to.AbsoluteDifference(from));
 105         float dist = length(diff);
 106         if (dist > sight_dist || dot(diff / dist, aim.dir) < sight_angle) {
 107                 return false;
 108         }
 109         WorldCollision col;
 110         if (world.Intersection(aim, reference, col) && col.depth < dist) {
 111                 return false;
 112         }
 113         return true;
 114 }
 115
 116 // think
 117
 118 bool AIController::MayThink() const noexcept {
 119         return think_timer.Hit();
 120 }
 121
 122 void AIController::SetThinkInterval(float i) noexcept {
 123         think_timer = FineTimer(i);
 124         think_timer.Start();
 125 }
 126
 127 // decide
 128
 129 void AIController::CueDecision(
 130         float minimum,
 131         float variance
 132 ) noexcept {
 133         decision_timer = FineTimer(minimum + variance * world.Random().SNorm());
 134         decision_timer.Start();
 135 }
 136
 137 bool AIController::DecisionDue() const noexcept {
 138         return decision_timer.HitOnce();
 139 }
 140
 141 unsigned int AIController::Decide(unsigned int num_choices) noexcept {
 142         return world.Random().Next<unsigned int>() % num_choices;
 143 }
 144
 145
 146 // chase
 147
 148 void ChaseState::Enter(AIController &ctrl, Entity &e) const {
 149         e.GetSteering()
 150                 .SetAcceleration(1.0f)
 151                 .SetSpeed(4.0f)
 152                 .Enable(Steering::PURSUE_TARGET)
 153         ;
 154 }
 155
 156 void ChaseState::Update(AIController &ctrl, Entity &e, float dt) const {
 157         Steering &steering = e.GetSteering();
 158         // check if target still alive and in sight
 159         if (
 160                 !steering.HasTargetEntity() || // lost
 161                 steering.GetTargetEntity().Dead() || // dead
 162                 !ctrl.LineOfSight(e, steering.GetTargetEntity()) // escaped
 163         ) {
 164                 steering.ClearTargetEntity();
 165                 ctrl.SetState(idle, e);
 166                 return;
 167         }
 168         // halt if we're close enough, flee if we're too close
 169         float dist_sq = length2(e.AbsoluteDifference(steering.GetTargetEntity()));
 170         if (dist_sq < 8.0f) {
 171                 ctrl.SetState(flee, e);
 172         } else if (dist_sq < 25.0f) {
 173                 steering.Enable(Steering::HALT).Disable(Steering::PURSUE_TARGET);
 174         } else {
 175                 steering.Enable(Steering::PURSUE_TARGET).Disable(Steering::HALT);
 176         }
 177 }
 178
 179 void ChaseState::Exit(AIController &ctrl, Entity &e) const {
 180         e.GetSteering().Disable(Steering::HALT | Steering::PURSUE_TARGET);
 181 }
 182
 183 // flee
 184
 185 void FleeState::Enter(AIController &ctrl, Entity &e) const {
 186         e.GetSteering()
 187                 .SetAcceleration(1.0f)
 188                 .SetSpeed(4.0f)
 189                 .Enable(Steering::EVADE_TARGET)
 190         ;
 191         ctrl.CueDecision(6.0f, 3.0f);
 192 }
 193
 194 void FleeState::Update(AIController &ctrl, Entity &e, float dt) const {
 195         if (!ctrl.DecisionDue()) return;
 196         ctrl.SetState(idle, e);
 197 }
 198
 199 void FleeState::Exit(AIController &ctrl, Entity &e) const {
 200         e.GetSteering().Disable(Steering::EVADE_TARGET);
 201 }
 202
 203 // idle
 204
 205 void IdleState::Enter(AIController &ctrl, Entity &e) const {
 206         e.GetSteering()
 207                 .SetAcceleration(0.5f)
 208                 .SetSpeed(0.01f)
 209                 .Enable(Steering::HALT)
 210                 .SetWanderParams(1.0f, 1.1f, 1.0f)
 211         ;
 212         ctrl.CueDecision(10.0f, 5.0f);
 213 }
 214
 215 void IdleState::Update(AIController &ctrl, Entity &e, float dt) const {
 216         if (ctrl.MayThink()) {
 217                 const Player *player = ctrl.ClosestVisiblePlayer(e);
 218                 if (player) {
 219                         e.GetSteering().SetTargetEntity(player->GetEntity());
 220                         ctrl.SetState(chase, e);
 221                         return;
 222                 }
 223         }
 224
 225         if (!ctrl.DecisionDue()) return;
 226
 227         unsigned int d = ctrl.Decide(10);
 228         if (d < 2) {
 229                 // .2 chance to start going
 230                 ctrl.SetState(roam, e);
 231         } else if (d < 5) {
 232                 // .3 chance of looking around
 233                 e.GetSteering().Disable(Steering::HALT).Enable(Steering::WANDER);
 234         } else {
 235                 // .5 chance of doing nothing
 236                 e.GetSteering().Disable(Steering::WANDER).Enable(Steering::HALT);
 237         }
 238         ctrl.CueDecision(10.0f, 5.0f);
 239 }
 240
 241 void IdleState::Exit(AIController &ctrl, Entity &e) const {
 242         e.GetSteering().Disable(Steering::HALT | Steering::WANDER);
 243 }
 244
 245 // roam
 246
 247 void RoamState::Enter(AIController &ctrl, Entity &e) const {
 248         e.GetSteering()
 249                 .SetAcceleration(0.5f)
 250                 .SetSpeed(1.0f)
 251                 .SetWanderParams(1.0f, 2.0f, 1.0f)
 252                 .Enable(Steering::WANDER)
 253         ;
 254         ctrl.CueDecision(10.0f, 5.0f);
 255 }
 256
 257 void RoamState::Update(AIController &ctrl, Entity &e, float dt) const {
 258         if (ctrl.MayThink()) {
 259                 const Player *player = ctrl.ClosestVisiblePlayer(e);
 260                 if (player) {
 261                         e.GetSteering().SetTargetEntity(player->GetEntity());
 262                         ctrl.SetState(chase, e);
 263                         return;
 264                 }
 265         }
 266
 267         if (!ctrl.DecisionDue()) return;
 268
 269         unsigned int d = ctrl.Decide(10);
 270         if (d == 0) {
 271                 // .1 chance of idling
 272                 ctrl.SetState(idle, e);
 273         }
 274         ctrl.CueDecision(10.0f, 5.0f);
 275 }
 276
 277 void RoamState::Exit(AIController &ctrl, Entity &e) const {
 278         e.GetSteering().Disable(Steering::WANDER);
 279 }
 280
 281 }