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#include <algorithm>
#include <cmath>
#include "manager/ComponentManager.h"
#include "manager/LoopTimerManager.h"
#include "manager/Mediator.h"
#include "AISystem.h"
using namespace crepe;
using namespace std::chrono;
void AISystem::fixed_update() {
const Mediator & mediator = this->mediator;
ComponentManager & mgr = mediator.component_manager;
LoopTimerManager & loop_timer = mediator.loop_timer;
RefVector<AI> ai_components = mgr.get_components_by_type<AI>();
float dt = loop_timer.get_scaled_fixed_delta_time().count();
// Loop through all AI components
for (AI & ai : ai_components) {
if (!ai.active) {
continue;
}
RefVector<Rigidbody> rigidbodies
= mgr.get_components_by_id<Rigidbody>(ai.game_object_id);
if (rigidbodies.empty()) {
throw std::runtime_error(
"AI component must be attached to a GameObject with a Rigidbody component"
);
}
Rigidbody & rigidbody = rigidbodies.front().get();
if (!rigidbody.active) {
continue;
}
if (rigidbody.data.mass <= 0) {
throw std::runtime_error("Mass must be greater than 0");
}
// Calculate the force to apply to the entity
vec2 force = this->calculate(ai, rigidbody);
// Calculate the acceleration (using the above calculated force)
vec2 acceleration = force / rigidbody.data.mass;
// Finally, update Rigidbody's velocity
rigidbody.data.linear_velocity += acceleration * dt;
}
}
vec2 AISystem::calculate(AI & ai, const Rigidbody & rigidbody) {
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();
vec2 force;
// Run all the behaviors that are on, and stop if the force gets too high
if (ai.on(AI::BehaviorTypeMask::FLEE)) {
vec2 force_to_add = this->flee(ai, rigidbody, transform);
if (!this->accumulate_force(ai, force, force_to_add)) {
return force;
}
}
if (ai.on(AI::BehaviorTypeMask::ARRIVE)) {
vec2 force_to_add = this->arrive(ai, rigidbody, transform);
if (!this->accumulate_force(ai, force, force_to_add)) {
return force;
}
}
if (ai.on(AI::BehaviorTypeMask::SEEK)) {
vec2 force_to_add = this->seek(ai, rigidbody, transform);
if (!this->accumulate_force(ai, force, force_to_add)) {
return force;
}
}
if (ai.on(AI::BehaviorTypeMask::PATH_FOLLOW)) {
vec2 force_to_add = this->path_follow(ai, rigidbody, transform);
if (!this->accumulate_force(ai, force, force_to_add)) {
return force;
}
}
return force;
}
bool AISystem::accumulate_force(const 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) {
// If the force is already at/above the max force, return false
return false;
}
float magnitude_to_add = force_to_add.length();
if (magnitude_to_add < magnitude_remaining) {
// If the force to add is less than the remaining force, add it
running_total += force_to_add;
} else {
// If the force to add is greater than the remaining force, add a fraction of it
force_to_add.normalize();
running_total += force_to_add * magnitude_remaining;
}
return true;
}
vec2 AISystem::seek(const AI & ai, const Rigidbody & rigidbody, const Transform & transform)
const {
// Calculate the desired velocity
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 Rigidbody & rigidbody, const Transform & transform)
const {
// Calculate the desired velocity if the entity is within the panic distance
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 Rigidbody & rigidbody, const Transform & transform)
const {
// Calculate the desired velocity (taking into account the deceleration rate)
vec2 to_target = ai.arrive_target - transform.position;
float distance = to_target.length();
if (distance > 0.0f) {
if (ai.arrive_deceleration <= 0.0f) {
throw std::runtime_error("Deceleration rate must be greater than 0");
}
float speed = distance / ai.arrive_deceleration;
speed = std::min(speed, rigidbody.data.max_linear_velocity);
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 Rigidbody & rigidbody, const Transform & transform) {
if (ai.path.empty()) {
return vec2 {0, 0};
}
// Get the target node
vec2 target = ai.path.at(ai.path_index);
// Calculate the force to apply to the entity
vec2 to_target = target - transform.position;
if (to_target.length_squared() > ai.path_node_distance * ai.path_node_distance) {
// If the entity is not close enough to the target node, seek it
ai.seek_target = target;
ai.arrive_target = target;
} else {
// If the entity is close enough to the target node, move to the next node
ai.path_index++;
if (ai.path_index >= ai.path.size()) {
if (ai.path_loop) {
// If the path is looping, reset the path index
ai.path_index = 0;
} else {
// If the path is not looping, arrive at the last node
ai.path_index = ai.path.size() - 1;
return this->arrive(ai, rigidbody, transform);
}
}
}
// Seek the target node
return this->seek(ai, rigidbody, transform);
}
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