cs381/as6/components/PhysicsComponent.cpp

#include "components/PhysicsComponent.hpp"

#include "Entity.hpp"
#include "components/GravityWellComponent.hpp"
#include "components/NullZoneComponent.hpp"
#include "components/StatsComponent.hpp"
#include "components/TransformComponent.hpp"

#include <algorithm>
#include <cmath>

void PhysicsComponent::Setup() {}

void PhysicsComponent::ClampVelocity(float &vxRef, float &vyRef) const {
    const float speed = std::sqrt(vxRef * vxRef + vyRef * vyRef);
    if (speed > speedCap && speed > 0.0f) {
        const float scale = speedCap / speed;
        vxRef *= scale;
        vyRef *= scale;
    }
}

void PhysicsComponent::ClampVelocity(double &vxRef, double &vyRef) const {
    const double speed = std::sqrt(vxRef * vxRef + vyRef * vyRef);
    if (speed > static_cast<double>(speedCap) && speed > 0.0) {
        const double scale = static_cast<double>(speedCap) / speed;
        vxRef *= scale;
        vyRef *= scale;
    }
}

void PhysicsComponent::IntegratePosition(float &xRef, float &yRef, float vxValue, float vyValue,
                                         float dt) {
    xRef += vxValue * dt;
    yRef += vyValue * dt;
}

void PhysicsComponent::IntegratePosition(double &xRef, double &yRef, double vxValue, double vyValue,
                                         double dt) {
    xRef += vxValue * dt;
    yRef += vyValue * dt;
}

bool PhysicsComponent::IsInsideNullZone(double xPos) const {
    if (!context || !context->entities) {
        return false;
    }

    for (auto &other : *context->entities) {
        if (!other || other.get() == entity) {
            continue;
        }

        auto zone = other->GetComponent<NullZoneComponent>();
        auto zoneTransform = other->GetComponent<TransformComponent>();
        if (!zone || !zoneTransform) {
            continue;
        }

        const double left = static_cast<double>(zoneTransform->get().x);
        const double right = left + static_cast<double>(zone->get().width);
        if (xPos >= left && xPos <= right) {
            return true;
        }
    }

    return false;
}

bool PhysicsComponent::ComputeGravityDeltaVelocity(double px, double py, double dt, double &dvx,
                                                   double &dvy, bool ignoreWellActive) const {
    dvx = 0.0;
    dvy = 0.0;

    if (!context || !context->entities) {
        return false;
    }

    bool probeMeterDepleted = false;
    if (context && entity == context->probeEntity && context->statsEntity) {
        auto stats = context->statsEntity->GetComponent<StatsComponent>();
        if (stats && stats->get().value <= 0.0f) {
            probeMeterDepleted = true;
        }
    }

    if (IsInsideNullZone(px)) {
        return false;
    }

    bool applied = false;
    for (auto &other : *context->entities) {
        if (!other || other.get() == entity) {
            continue;
        }

        auto wellTransform = other->GetComponent<TransformComponent>();
        auto wellGravity = other->GetComponent<GravityWellComponent>();
        if (!wellTransform || !wellGravity) {
            continue;
        }

        if (probeMeterDepleted && !wellGravity->get().alwaysActive) {
            continue;
        }

        if (!ignoreWellActive && !wellGravity->get().active) {
            continue;
        }

        const double dx = static_cast<double>(wellTransform->get().x) - px;
        const double dy = static_cast<double>(wellTransform->get().y) - py;
        const double dist = std::sqrt(dx * dx + dy * dy);
        if (dist <= 0.0001) {
            continue;
        }

        const double clampedDist = std::max(dist, static_cast<double>(wellGravity->get().minDist));
        const double force =
            static_cast<double>(wellGravity->get().mass) / (clampedDist * clampedDist);
        dvx += (dx / dist) * force * dt;
        dvy += (dy / dist) * force * dt;
        applied = true;
    }

    return applied;
}

void PhysicsComponent::SimulateStep(double &xRef, double &yRef, double &vxRef, double &vyRef,
                                    double dt, bool ignoreWellActive) const {
    double dvx = 0.0;
    double dvy = 0.0;
    ComputeGravityDeltaVelocity(xRef, yRef, dt, dvx, dvy, ignoreWellActive);
    vxRef += dvx;
    vyRef += dvy;

    ClampVelocity(vxRef, vyRef);
    IntegratePosition(xRef, yRef, vxRef, vyRef, dt);
}

void PhysicsComponent::Update(float dt) {
    auto transform = entity->GetComponent<TransformComponent>();
    if (!transform) {
        return;
    }

    double x = static_cast<double>(transform->get().x);
    double y = static_cast<double>(transform->get().y);
    double vxLocal = static_cast<double>(vx);
    double vyLocal = static_cast<double>(vy);

    SimulateStep(x, y, vxLocal, vyLocal, static_cast<double>(dt), false);

    transform->get().x = static_cast<float>(x);
    transform->get().y = static_cast<float>(y);
    vx = static_cast<float>(vxLocal);
    vy = static_cast<float>(vyLocal);
}

void PhysicsComponent::Cleanup() {}