Add trails and projections

as6/components/PhysicsComponent.cpp

@@ -1,27 +1,137 @@
 #include "components/PhysicsComponent.hpp"
 
 #include "Entity.hpp"
+#include "components/GravityWellComponent.hpp"
+#include "components/NullZoneComponent.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::ComputeWellDeltaVelocity(double px, double py, double dt, double &dvx,
+                                                double &dvy, bool ignoreWellActive) const {
+    dvx = 0.0;
+    dvy = 0.0;
+
+    if (!context || !context->wellEntity) {
+        return false;
+    }
+
+    auto wellTransform = context->wellEntity->GetComponent<TransformComponent>();
+    auto wellGravity = context->wellEntity->GetComponent<GravityWellComponent>();
+    if (!wellTransform || !wellGravity) {
+        return false;
+    }
+
+    if (!ignoreWellActive && !wellGravity->get().active) {
+        return false;
+    }
+
+    if (IsInsideNullZone(px)) {
+        return false;
+    }
+
+    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) {
+        return false;
+    }
+
+    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;
+    return true;
+}
+
+void PhysicsComponent::SimulateStep(double &xRef, double &yRef, double &vxRef, double &vyRef,
+                                    double dt, bool ignoreWellActive) const {
+    double dvx = 0.0;
+    double dvy = 0.0;
+    ComputeWellDeltaVelocity(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;
     }
 
-    const float speed = std::sqrt(vx * vx + vy * vy);
-    if (speed > speedCap && speed > 0.0f) {
-        const float scale = speedCap / speed;
-        vx *= scale;
-        vy *= scale;
-    }
+    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);
 
-    transform->get().x += vx * dt;
-    transform->get().y += vy * dt;
+    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() {}

as6/components/PhysicsComponent.hpp

@@ -10,6 +10,38 @@ struct PhysicsComponent : public Component {
     float vy = 0.0f;
     float speedCap = 400.0f;
 
+    /**
+     * Clamps the provided velocity vector to this component's speed cap.
+     */
+    void ClampVelocity(float &vxRef, float &vyRef) const;
+    void ClampVelocity(double &vxRef, double &vyRef) const;
+
+    /**
+     * Integrates a position by velocity over dt.
+     */
+    static void IntegratePosition(float &xRef, float &yRef, float vxValue, float vyValue, float dt);
+    static void IntegratePosition(double &xRef, double &yRef, double vxValue, double vyValue,
+                                  double dt);
+
+    /**
+     * Returns true when the given X position is inside a null zone.
+     */
+    bool IsInsideNullZone(double xPos) const;
+
+    /**
+     * Computes velocity delta from well gravity for a position.
+     * Returns false when gravity should not apply.
+     */
+    bool ComputeWellDeltaVelocity(double px, double py, double dt, double &dvx, double &dvy,
+                                  bool ignoreWellActive = false) const;
+
+    /**
+     * Performs one projected simulation step using well/null-zone rules,
+     * velocity clamp, and position integration.
+     */
+    void SimulateStep(double &xRef, double &yRef, double &vxRef, double &vyRef, double dt,
+                      bool ignoreWellActive = false) const;
+
     void Setup() override;
     void Update(float dt) override;
     void Cleanup() override;

as6/components/ProbeStateComponent.cpp

@@ -19,7 +19,8 @@ void ProbeStateComponent::Update(float) {
 
     if (transform->get().y < -20.0f ||
         transform->get().y > static_cast<float>(GetScreenHeight() + 20) ||
-        transform->get().x < -20.0f) {
+        transform->get().x < -20.0f ||
+        transform->get().x > static_cast<float>(GetScreenWidth() + 20)) {
         if (context->onPlayerDeath) {
             context->onPlayerDeath();
         }

as6/components/ProjectionComponent.cpp

@@ -1,5 +1,74 @@
 #include "components/ProjectionComponent.hpp"
 
-void ProjectionComponent::Setup() {}
-void ProjectionComponent::Update(float) {}
-void ProjectionComponent::Cleanup() {}
+#include "Entity.hpp"
+#include "components/GravityReceiverComponent.hpp"
+#include "components/GravityWellComponent.hpp"
+#include "components/PhysicsComponent.hpp"
+#include "components/TransformComponent.hpp"
+
+void ProjectionComponent::Setup() { points.clear(); }
+
+void ProjectionComponent::Update(float) {
+    points.clear();
+    highlightActive = false;
+
+    if (!context || !context->probeEntity || entity != context->probeEntity) {
+        return;
+    }
+
+    auto transform = entity->GetComponent<TransformComponent>();
+    auto physics = entity->GetComponent<PhysicsComponent>();
+    auto receiver = entity->GetComponent<GravityReceiverComponent>();
+    if (!transform || !physics || !receiver) {
+        return;
+    }
+
+    Entity *wellEntity = receiver->get().well ? receiver->get().well : context->wellEntity;
+    if (!wellEntity) {
+        return;
+    }
+
+    auto wellTransform = wellEntity->GetComponent<TransformComponent>();
+    auto wellGravity = wellEntity->GetComponent<GravityWellComponent>();
+    if (!wellTransform || !wellGravity) {
+        return;
+    }
+
+    // only highlight if the well is active, inactive will be a lighter color to show the potential
+    // projection if the player were to activate it
+    highlightActive = wellGravity->get().active;
+
+    double px = static_cast<double>(transform->get().x);
+    double py = static_cast<double>(transform->get().y);
+    double vx = static_cast<double>(physics->get().vx);
+    double vy = static_cast<double>(physics->get().vy);
+
+    points.reserve(static_cast<size_t>(steps));
+    for (int i = 0; i < steps; ++i) {
+        physics->get().SimulateStep(px, py, vx, vy, static_cast<double>(stepDt), true);
+        points.push_back({static_cast<float>(px), static_cast<float>(py)});
+    }
+
+    Draw();
+}
+
+void ProjectionComponent::Cleanup() { points.clear(); }
+
+void ProjectionComponent::Draw() const {
+    if (points.empty()) {
+        return;
+    }
+
+    const Color base = highlightActive ? activeColor : inactiveColor;
+    for (size_t i = 0; i < points.size(); ++i) {
+        // t goes from 0 to 1 across the points, used for fading effect
+        const float t = (points.size() <= 1) ? 0.0f : (float)i / (points.size() - 1);
+        Color c = base;
+        float alphaScale = 1.0f - t;
+
+        // multiply alpha to make it fade towards the end
+        c.a = (unsigned char)((float)(base.a) * alphaScale);
+
+        DrawCircleV(points[i], pointRadius, c);
+    }
+}

as6/components/ProjectionComponent.hpp

@@ -2,11 +2,25 @@
 
 #include "Component.hpp"
 
+#include "raylib.h"
+
+#include <vector>
+
 /**
- * Placeholder for future trajectory projection behavior.
+ * Predicts and renders the probe's near-future trajectory.
  */
 struct ProjectionComponent : public Component {
+    std::vector<Vector2> points;
+    int steps = 30;
+    float stepDt = 1.0f / 60.0f;
+    float pointRadius = 2.4f;
+    bool highlightActive = false;
+    Color inactiveColor = Color{125, 146, 178, 120};
+    Color activeColor = Color{160, 206, 255, 220};
+
     void Setup() override;
     void Update(float dt) override;
     void Cleanup() override;
+
+    void Draw() const;
 };

as6/components/TrailComponent.cpp

@@ -1,5 +1,94 @@
 #include "components/TrailComponent.hpp"
 
-void TrailComponent::Setup() {}
-void TrailComponent::Update(float) {}
-void TrailComponent::Cleanup() {}
+#include "Entity.hpp"
+#include "components/TransformComponent.hpp"
+
+#include <algorithm>
+#include <cmath>
+
+void TrailComponent::Setup() {
+    points.clear();
+    elapsed = 0.0f;
+    lastSampleAt = 0.0f;
+
+    auto transform = entity->GetComponent<TransformComponent>();
+    if (!transform) {
+        return;
+    }
+
+    points.push_back({transform->get().x, transform->get().y, elapsed});
+}
+
+void TrailComponent::Update(float dt) {
+    elapsed += dt;
+
+    auto transform = entity->GetComponent<TransformComponent>();
+    if (!transform) {
+        return;
+    }
+
+    while (!points.empty() && (elapsed - points.front().createdAt) > pointLifetime) {
+        points.pop_front();
+    }
+
+    const float x = transform->get().x;
+    const float y = transform->get().y;
+    if (points.empty()) {
+        points.push_back({x, y, elapsed});
+        lastSampleAt = elapsed;
+        return;
+    }
+
+    const Point &last = points.back();
+    const float dx = x - last.x;
+    const float dy = y - last.y;
+
+    // check if we've moved far enough from the last point or if enough time has passed to warrant a
+    // new sample, for smoother trails when the probe is moving slowly
+    const bool movedEnough = (dx * dx + dy * dy) >= (sampleDistance * sampleDistance);
+    const bool waitedEnough = (elapsed - lastSampleAt) >= sampleInterval;
+    if (movedEnough || waitedEnough) {
+        points.push_back({x, y, elapsed});
+        lastSampleAt = elapsed;
+    } else {
+        points.back().x = x;
+        points.back().y = y;
+        points.back().createdAt = elapsed;
+    }
+
+    if (points.size() > maxPoints) {
+        while (points.size() > maxPoints) {
+            points.pop_front();
+        }
+    }
+
+    Draw();
+}
+
+void TrailComponent::Cleanup() {
+    points.clear();
+    elapsed = 0.0f;
+    lastSampleAt = 0.0f;
+}
+
+void TrailComponent::Draw() const {
+    if (points.size() < 2 || pointLifetime <= 0.0f) {
+        return;
+    }
+
+    for (size_t i = 1; i < points.size(); ++i) {
+        const Point &a = points[i - 1];
+        const Point &b = points[i];
+
+        const float ageA = elapsed - a.createdAt;
+        const float ageB = elapsed - b.createdAt;
+        const float lifeNormA = std::clamp(1.0f - (ageA / pointLifetime), 0.0f, 1.0f);
+        const float lifeNormB = std::clamp(1.0f - (ageB / pointLifetime), 0.0f, 1.0f);
+        const float lifeNorm = 0.5f * (lifeNormA + lifeNormB);
+
+        Color c = color;
+        c.a = (unsigned char)((float)(color.a) * lifeNorm);
+
+        DrawLineEx({a.x, a.y}, {b.x, b.y}, lineWidth, c);
+    }
+}

as6/components/TrailComponent.hpp

@@ -2,11 +2,37 @@
 
 #include "Component.hpp"
 
+#include "raylib.h"
+
+#include <cstddef>
+#include <deque>
+
 /**
- * Placeholder for future probe trail visualization.
+ * Stores and renders a fading positional trail for moving entities.
+ *
+ * Points are timestamped and retired from the front of a queue once they
+ * exceed `pointLifetime`, so updates avoid touching every point each frame.
  */
 struct TrailComponent : public Component {
+    struct Point {
+        float x = 0.0f;
+        float y = 0.0f;
+        float createdAt = 0.0f;
+    };
+
+    std::deque<Point> points;
+    float elapsed = 0.0f;
+    float lastSampleAt = 0.0f;
+    float sampleDistance = 5.0f;
+    float sampleInterval = 1.0f / 30.0f;
+    float pointLifetime = 0.85f;
+    float lineWidth = 2.0f;
+    std::size_t maxPoints = 96;
+    Color color = Color{120, 210, 255, 180};
+
     void Setup() override;
     void Update(float dt) override;
     void Cleanup() override;
+
+    void Draw() const;
 };