add live ship stats panel

src/lib/sim/EntityHitTest.cpp

@@ -0,0 +1,56 @@
+#include "EntityHitTest.h"
+
+#include <cmath>
+
+#include "EntityAdmin.h"
+#include "PositionComponent.h"
+#include "StationBodyComponent.h"
+#include "HealthComponent.h"
+
+entt::entity entityAtWorldPos(EntityAdmin& admin, QVector2D worldPos)
+{
+    const QPoint tile(static_cast<int>(std::floor(worldPos.x())),
+                      static_cast<int>(std::floor(worldPos.y())));
+
+    entt::entity stationHit = entt::null;
+    admin.forEach<StationBodyComponent, HealthComponent>(
+        [&](entt::entity entity, const StationBodyComponent& sb, const HealthComponent& h)
+        {
+            if (stationHit != entt::null) { return; }
+            if (h.hp <= 0.0f) { return; }
+            for (const QPoint& cell : sb.bodyCells)
+            {
+                if (cell == tile)
+                {
+                    stationHit = entity;
+                    return;
+                }
+            }
+        });
+
+    if (stationHit != entt::null)
+    {
+        return stationHit;
+    }
+
+    constexpr float kShipHitRadiusSquared = 0.5f * 0.5f;
+    entt::entity bestShip = entt::null;
+    float bestDistSquared = kShipHitRadiusSquared;
+
+    admin.forEach<PositionComponent, HealthComponent>(
+        [&](entt::entity entity, const PositionComponent& pos, const HealthComponent& h)
+        {
+            if (h.hp <= 0.0f) { return; }
+            if (admin.hasAll<StationBodyComponent>(entity)) { return; }
+            const float dx = pos.value.x() - worldPos.x();
+            const float dy = pos.value.y() - worldPos.y();
+            const float distSquared = dx * dx + dy * dy;
+            if (distSquared < bestDistSquared)
+            {
+                bestDistSquared = distSquared;
+                bestShip = entity;
+            }
+        });
+
+    return bestShip;
+}