Add main loop

as6/components/PhysicsComponent.cpp

@@ -2,6 +2,7 @@
 
 #include "Entity.hpp"
 #include "components/GravityWellComponent.hpp"
+#include "components/MeterComponent.hpp"
 #include "components/NullZoneComponent.hpp"
 #include "components/TransformComponent.hpp"
 
@@ -85,6 +86,14 @@ bool PhysicsComponent::ComputeWellDeltaVelocity(double px, double py, double dt,
         return false;
     }
 
+    // Probe cannot receive well acceleration when meter is depleted.
+    if (context && entity == context->probeEntity && context->hudEntity) {
+        auto meter = context->hudEntity->GetComponent<MeterComponent>();
+        if (meter && meter->get().value <= 0.0f) {
+            return false;
+        }
+    }
+
     if (IsInsideNullZone(px)) {
         return false;
     }

as6/components/SpawnComponent.cpp

@@ -1,5 +1,87 @@
 #include "components/SpawnComponent.hpp"
 
-void SpawnComponent::Setup() {}
-void SpawnComponent::Update(float) {}
+#include "Entities.hpp"
+#include "Entity.hpp"
+#include "components/CollectibleComponent.hpp"
+#include "components/HazardComponent.hpp"
+#include "components/NullZoneComponent.hpp"
+#include "components/ScrollComponent.hpp"
+#include "components/ScrollableComponent.hpp"
+#include "components/TransformComponent.hpp"
+
+#include "raylib.h"
+
+#include <algorithm>
+
+void SpawnComponent::Setup() {
+    // Start a bit beyond the initial handcrafted segment.
+    cursorWX = 1500.0f;
+}
+
+void SpawnComponent::Update(float) {
+    if (!context || !context->entities) {
+        return;
+    }
+
+    auto scroll = entity->GetComponent<ScrollComponent>();
+    if (!scroll) {
+        return;
+    }
+
+    const float cameraX = scroll->get().scrollX;
+    const float spawnLimit = cameraX + spawnAheadDistance;
+
+    while (cursorWX < spawnLimit) {
+        const float r = static_cast<float>(GetRandomValue(0, 99));
+        if (r < 55.0f) {
+            const float y = static_cast<float>(GetRandomValue(48, GetScreenHeight() - 48));
+            auto star = CreateStar(cursorWX, y);
+            star->SetContext(context);
+            context->entities->push_back(star);
+        } else if (r < 88.0f) {
+            const float y = static_cast<float>(GetRandomValue(42, GetScreenHeight() - 42));
+            auto asteroid = CreateAsteroid(cursorWX, y);
+            asteroid->SetContext(context);
+            context->entities->push_back(asteroid);
+        } else {
+            const float width = static_cast<float>(GetRandomValue(70, 140));
+            auto zone = CreateNullZone(cursorWX, width);
+            zone->SetContext(context);
+            context->entities->push_back(zone);
+        }
+
+        const float gap =
+            static_cast<float>(GetRandomValue(static_cast<int>(minGap), static_cast<int>(maxGap)));
+        cursorWX += gap;
+    }
+
+    const float cullX = cameraX - despawnBehindDistance;
+    for (auto &candidate : *context->entities) {
+        if (!candidate || candidate.get() == entity || candidate->queuedForFree) {
+            continue;
+        }
+
+        const bool isSpawnedGameplayObject =
+            candidate->GetComponent<CollectibleComponent>().has_value() ||
+            candidate->GetComponent<HazardComponent>().has_value() ||
+            candidate->GetComponent<NullZoneComponent>().has_value();
+        if (!isSpawnedGameplayObject) {
+            continue;
+        }
+
+        auto scrollable = candidate->GetComponent<ScrollableComponent>();
+        if (scrollable) {
+            if (scrollable->get().worldX < cullX) {
+                candidate->QueueFree();
+            }
+            continue;
+        }
+
+        auto transform = candidate->GetComponent<TransformComponent>();
+        if (transform && transform->get().x < cullX) {
+            candidate->QueueFree();
+        }
+    }
+}
+
 void SpawnComponent::Cleanup() {}

as6/components/SpawnComponent.hpp

@@ -3,10 +3,29 @@
 #include "Component.hpp"
 
 /**
- * Placeholder for spawn cursor/state while spawning system evolves.
+ * Spawns and despawns gameplay objects to keep the run effectively infinite.
  */
 struct SpawnComponent : public Component {
+    /**
+     * Next world-space X coordinate where a spawn roll will happen.
+     */
     float cursorWX = 0.0f;
+    /**
+     * How far ahead of current scroll we keep content generated.
+     */
+    float spawnAheadDistance = 1200.0f;
+    /**
+     * How far behind the camera entities are culled.
+     */
+    float despawnBehindDistance = 180.0f;
+    /**
+     * Minimum spacing between spawn rolls.
+     */
+    float minGap = 160.0f;
+    /**
+     * Maximum spacing between spawn rolls.
+     */
+    float maxGap = 320.0f;
 
     void Setup() override;
     void Update(float dt) override;

as6/scene/GameplayScene.cpp

@@ -20,30 +20,32 @@ void GameplayScene::Enter() {
             return;
         }
 
-        context.entities->push_back(
+        context.entities->emplace_back(
             CreateDebris(transform->get().x - 4.0f, transform->get().y, -22.0f, -36.0f));
-        context.entities->push_back(
+        context.entities->emplace_back(
             CreateDebris(transform->get().x + 4.0f, transform->get().y, 24.0f, -28.0f));
     });
     context.AddMeterChangedListener([this](float, float newValue) { meterValue = newValue; });
 
-    entities.push_back(CreateWorld());
-    entities.push_back(CreateGravityWell());
-    entities.push_back(CreateProbe());
-    entities.push_back(CreateStar(900.0f, 120.0f));
-    entities.push_back(CreateAsteroid(1100.0f, 330.0f));
-    entities.push_back(CreateNullZone(1280.0f, 120.0f));
-    entities.push_back(CreateHUD());
+    context.worldEntity = entities.emplace_back(CreateWorld()).get();
 
-    if (auto meter = entities.back()->GetComponent<MeterComponent>()) {
+    context.wellEntity = entities.emplace_back(CreateGravityWell()).get();
+
+    context.probeEntity = entities.emplace_back(CreateProbe()).get();
+
+    entities.emplace_back(CreateStar(900.0f, 230.0f));
+    entities.emplace_back(CreateNullZone(1280.0f, 120.0f));
+
+    context.hudEntity = entities.emplace_back(CreateHUD()).get();
+
+    if (context.hudEntity) {
+        auto meter = context.hudEntity->GetComponent<MeterComponent>();
+        if (meter) {
             meterValue = meter->get().value;
         }
+    }
 
     context.entities = &entities;
-    context.worldEntity = (entities.size() > 0 && entities[0]) ? entities[0].get() : nullptr;
-    context.wellEntity = (entities.size() > 1 && entities[1]) ? entities[1].get() : nullptr;
-    context.probeEntity = (entities.size() > 2 && entities[2]) ? entities[2].get() : nullptr;
-    context.hudEntity = (!entities.empty() && entities.back()) ? entities.back().get() : nullptr;
 
     for (auto &entity : entities) {
         if (!entity) {
@@ -56,11 +58,6 @@ void GameplayScene::Enter() {
 void GameplayScene::Update(float dt) {
     UpdateAllSystems(entities, dt);
 
-    context.worldEntity = (entities.size() > 0 && entities[0]) ? entities[0].get() : nullptr;
-    context.wellEntity = (entities.size() > 1 && entities[1]) ? entities[1].get() : nullptr;
-    context.probeEntity = (entities.size() > 2 && entities[2]) ? entities[2].get() : nullptr;
-    context.hudEntity = (!entities.empty() && entities.back()) ? entities.back().get() : nullptr;
-
     if (wantsDeathScene) {
         manager.QueueSceneChange<DeathScene>();
     }
@@ -70,8 +67,15 @@ void GameplayScene::Draw() {
     DrawSceneOutline();
     DrawText("Gravity Surfing", 14, 12, 20, Color{230, 238, 255, 255});
 
-    auto worldScroll = entities[0]->GetComponent<ScrollComponent>();
-    auto probeTransform = entities[2]->GetComponent<TransformComponent>();
+    std::optional<std::reference_wrapper<ScrollComponent>> worldScroll;
+    if (context.worldEntity) {
+        worldScroll = context.worldEntity->GetComponent<ScrollComponent>();
+    }
+
+    std::optional<std::reference_wrapper<TransformComponent>> probeTransform;
+    if (context.probeEntity) {
+        probeTransform = context.probeEntity->GetComponent<TransformComponent>();
+    }
 
     if (worldScroll) {
         DrawText(TextFormat("scrollX: %.2f", worldScroll->get().scrollX), 14, 40, 16,