first pass add ecs

1 files changed, 71 insertions, 0 deletions

diff --git a/src/ecs.cpp b/src/ecs.cpp
new file mode 100644
index 0000000..2c0a26f
--- /dev/null
+++ b/src/ecs.cpp
@@ -0,0 +1,71 @@
+
+#include "ecs.hpp"
+
+TypeSafeInt_B(EntityHandle);
+const uint64_t bucketItemCount = 256;
+
+struct EntityBucket{
+	Entity entities[bucketItemCount];
+};
+
+uint64_t entityBucketIncrementer = 2;
+EntityHandle_T entityBucketCounter{0};
+EntityHandle_T entityCounter{0};
+EntityBucket *entityBuckets = nullptr;
+DynArray<EntityHandle> entitiesMarkedForRemoval{16};
+DynArray<EntityHandle> EntitiesToBeRemoved{16};
+
+void ECS_Init() {
+	entityBuckets = pke::PkeNew<EntityBucket>(entityBucketIncrementer);
+}
+
+EntityHandle ECS_CreateEntity_Inner(EntityHandle parentEntityHandle) {
+	EntityHandle_T entityHandle_T{Buckets_NewHandle<EntityBucket>(bucketItemCount, entityBucketIncrementer, entityBucketCounter, entityCounter, entityBuckets)};
+	EntityHandle entityHandle{entityHandle_T};
+
+	Entity *entity = &entityBuckets[Buckets_GetBucketIndex(entityHandle_T)].entities[Buckets_GetItemIndex(entityHandle_T)];
+
+	entity->handle = entityHandle;
+	entity->parentHandle = parentEntityHandle;
+
+	return entityHandle;
+}
+
+EntityHandle ECS_CreateEntity(EntityHandle parentEntityHandle) {
+	return ECS_CreateEntity_Inner(parentEntityHandle);
+}
+
+void ECS_MarkForRemoval(EntityHandle entityHandle) {
+	auto b = Buckets_GetBucketIndex(static_cast<EntityHandle_T>(entityHandle));
+	auto e = Buckets_GetItemIndex(static_cast<EntityHandle_T>(entityHandle));
+	const Entity *ent = &entityBuckets[b].entities[e];
+	assert(ent->isMarkedForRemoval == false && "Entity already marked for removal");
+	entitiesMarkedForRemoval.Push(entityHandle);
+}
+
+void ECS_Tick(double delta) {
+	EntitiesToBeRemoved.Resize(0);
+	for (long b = 0; b <= entityBucketCounter; ++b) {
+		uint64_t entCount = b == entityBucketCounter ? entityCounter >> 32 : bucketItemCount;
+		for (long e  = 0; e < entCount; ++e) {
+			Entity *ent = &entityBuckets[b].entities[e];
+			if (ent->handle == EntityHandle{EntityHandle_T{0xFFFFFFFFFFFFFFFF}}) continue;
+			if (ent->isMarkedForRemoval) {
+				ent->handle = EntityHandle{EntityHandle_T{0xFFFFFFFFFFFFFFFF}};
+				ent->parentHandle = EntityHandle{EntityHandle_T{0xFFFFFFFFFFFFFFFF}};
+				ent->isMarkedForRemoval = false;
+			} else {
+				if (entitiesMarkedForRemoval.Has(ent->handle)) {
+					ent->isMarkedForRemoval = true;
+					EntitiesToBeRemoved.Push(ent->handle);
+					continue;
+				}
+				if (EntitiesToBeRemoved.Has(ent->parentHandle)) {
+					ent->isMarkedForRemoval = true;
+					EntitiesToBeRemoved.Push(ent->handle);
+				}
+			}
+		}
+	}	
+	entitiesMarkedForRemoval.Resize(0);
+}