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#include <algorithm>
#include <cmath>
#include "api/LoopTimer.h"
#include "api/Rigidbody.h"
#include "api/Transform.h"
#include "manager/ComponentManager.h"
#include "manager/Mediator.h"
#include "AISystem.h"
#include "types.h"
using namespace crepe;
void AISystem::update() {
const Mediator & mediator = this->mediator;
ComponentManager & mgr = mediator.component_manager;
RefVector<AI> ai_components = mgr.get_components_by_type<AI>();
//TODO: Use fixed loop dt (this is not available at master at the moment)
double dt = LoopTimer::get_instance().get_delta_time();
for (AI & ai : ai_components) {
RefVector<Rigidbody> rigidbodies
= mgr.get_components_by_id<Rigidbody>(ai.game_object_id);
Rigidbody & rigidbody = rigidbodies.front().get();
vec2 force = this->calculate(ai);
vec2 acceleration = force / rigidbody.data.mass;
rigidbody.data.linear_velocity += acceleration * dt;
}
}
vec2 AISystem::calculate(AI & ai) {
vec2 force;
if (ai.on(AI::BehaviorType::FLEE)) {
vec2 force_to_add = this->flee(ai);
if (!this->accumulate_force(ai, force, force_to_add)) {
return force;
}
}
if (ai.on(AI::BehaviorType::ARRIVE)) {
vec2 force_to_add = this->arrive(ai);
if (!this->accumulate_force(ai, force, force_to_add)) {
return force;
}
}
if (ai.on(AI::BehaviorType::SEEK)) {
vec2 force_to_add = this->seek(ai);
if (!this->accumulate_force(ai, force, force_to_add)) {
return force;
}
}
if (ai.on(AI::BehaviorType::PATH_FOLLOW)) {
vec2 force_to_add = this->path_follow(ai);
if (!this->accumulate_force(ai, force, force_to_add)) {
return force;
}
}
return force;
}
bool AISystem::accumulate_force(AI & ai, vec2 & running_total, vec2 force_to_add) {
float magnitude = running_total.length();
float magnitude_remaining = ai.max_force - magnitude;
if (magnitude_remaining <= 0.0f) {
return false;
}
float magnitude_to_add = force_to_add.length();
if (magnitude_to_add < magnitude_remaining) {
running_total += force_to_add;
} else {
force_to_add.normalize();
running_total += force_to_add * magnitude_remaining;
}
return true;
}
vec2 AISystem::seek(const AI & ai) {
const Mediator & mediator = this->mediator;
ComponentManager & mgr = mediator.component_manager;
RefVector<Transform> transforms = mgr.get_components_by_id<Transform>(ai.game_object_id);
Transform & transform = transforms.front().get();
RefVector<Rigidbody> rigidbodies = mgr.get_components_by_id<Rigidbody>(ai.game_object_id);
Rigidbody & rigidbody = rigidbodies.front().get();
vec2 desired_velocity = ai.seek_target - transform.position;
desired_velocity.normalize();
desired_velocity *= rigidbody.data.max_linear_velocity;
return desired_velocity - rigidbody.data.linear_velocity;
}
vec2 AISystem::flee(const AI & ai) {
const Mediator & mediator = this->mediator;
ComponentManager & mgr = mediator.component_manager;
RefVector<Transform> transforms = mgr.get_components_by_id<Transform>(ai.game_object_id);
Transform & transform = transforms.front().get();
RefVector<Rigidbody> rigidbodies = mgr.get_components_by_id<Rigidbody>(ai.game_object_id);
Rigidbody & rigidbody = rigidbodies.front().get();
vec2 desired_velocity = transform.position - ai.flee_target;
if (desired_velocity.length_squared() > ai.square_flee_panic_distance) {
return vec2{0, 0};
}
desired_velocity.normalize();
desired_velocity *= rigidbody.data.max_linear_velocity;
return desired_velocity - rigidbody.data.linear_velocity;
}
vec2 AISystem::arrive(const AI & ai) {
const Mediator & mediator = this->mediator;
ComponentManager & mgr = mediator.component_manager;
RefVector<Transform> transforms = mgr.get_components_by_id<Transform>(ai.game_object_id);
Transform & transform = transforms.front().get();
RefVector<Rigidbody> rigidbodies = mgr.get_components_by_id<Rigidbody>(ai.game_object_id);
Rigidbody & rigidbody = rigidbodies.front().get();
vec2 to_target = ai.seek_target - transform.position;
float distance = to_target.length();
if (distance > 0.0f) {
float speed = distance / ai.arrive_deceleration;
speed = std::min(speed, rigidbody.data.max_linear_velocity.length());
vec2 desired_velocity = to_target * (speed / distance);
return desired_velocity - rigidbody.data.linear_velocity;
}
return vec2{0, 0};
}
vec2 AISystem::path_follow(AI & ai) {
const Mediator & mediator = this->mediator;
ComponentManager & mgr = mediator.component_manager;
RefVector<Transform> transforms = mgr.get_components_by_id<Transform>(ai.game_object_id);
Transform & transform = transforms.front().get();
RefVector<Rigidbody> rigidbodies = mgr.get_components_by_id<Rigidbody>(ai.game_object_id);
Rigidbody & rigidbody = rigidbodies.front().get();
if (ai.path.empty()) {
return vec2{0, 0};
}
vec2 to_target = ai.path.at(ai.path_index) - transform.position;
if (to_target.length_squared() > ai.path_node_distance * ai.path_node_distance) {
ai.seek_target = ai.path.at(ai.path_index);
} else {
ai.path_index++;
if (ai.path_index >= ai.path.size()) {
if (ai.path_loop) {
ai.path_index = 0;
} else {
ai.path_index = ai.path.size() - 1;
return this->arrive(ai);
}
}
}
return this->seek(ai);
}
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