Add Init,Update,Destroy to Comp+HasComp,DestroyComp funcs

entity/base_comp.go

@@ -0,0 +1,27 @@
+package entity
+
+import "github.com/bloeys/nmage/assert"
+
+var _ Comp = &BaseComp{}
+
+type BaseComp struct {
+	Entity *Entity
+}
+
+func (b *BaseComp) base() {
+}
+
+func (b *BaseComp) Init(parent *Entity) {
+	assert.T(parent != nil, "Component was initialized with a nil parent. That is not allowed.")
+	b.Entity = parent
+}
+
+func (b *BaseComp) Name() string {
+	return "Base Component"
+}
+
+func (b *BaseComp) Update() {
+}
+
+func (b *BaseComp) Destroy() {
+}

entity/comp.go

@@ -1,27 +1,37 @@
 package entity
 
+import "github.com/bloeys/nmage/assert"
+
 type Comp interface {
 	// This ensures that implementors of the Comp interface
 	// always embed BaseComp
 	base()
 
 	Name() string
+	Init(parent *Entity)
+	Update()
+	Destroy()
 }
 
-var _ Comp = &BaseComp{}
+func AddComp[T Comp](e *Entity, c T) {
 
-type BaseComp struct {
-}
+	assert.T(!HasComp[T](e), "Entity with id %v already has component with name %s", e.ID, c.Name())
 
-func (b *BaseComp) base() {
-}
-
-func (b *BaseComp) Name() string {
-	return "Base Component"
-}
-
-func AddComp(e *Entity, c Comp) {
 	e.Comps = append(e.Comps, c)
+	c.Init(e)
+}
+
+func HasComp[T Comp](e *Entity) bool {
+
+	for i := 0; i < len(e.Comps); i++ {
+
+		_, ok := e.Comps[i].(T)
+		if ok {
+			return true
+		}
+	}
+
+	return false
 }
 
 func GetComp[T Comp](e *Entity) (out T) {
@@ -37,16 +47,16 @@ func GetComp[T Comp](e *Entity) (out T) {
 	return out
 }
 
-func GetAllCompOfType[T Comp](e *Entity) (out []T) {
+// DestroyComp calls Destroy on the component and then removes it from the entities component list
+func DestroyComp[T Comp](e *Entity) {
 
-	out = []T{}
 	for i := 0; i < len(e.Comps); i++ {
 
 		comp, ok := e.Comps[i].(T)
 		if ok {
-			out = append(out, comp)
+			comp.Destroy()
+			e.Comps = append(e.Comps[:i], e.Comps[i+1:]...)
+			return
 		}
 	}
-
-	return out
 }

entity/entity.go

@@ -13,29 +13,31 @@ const (
 	IndexBitMask        = 0x00_00_FFFF_FFFF_FFFF
 )
 
+type EntityHandle uint64
+
 type Entity struct {
 
 	// Byte 1: Generation; Byte 2: Flags; Bytes 3-8: Index
-	ID    uint64
+	ID    EntityHandle
 	Comps []Comp
 }
 
-func GetGeneration(id uint64) byte {
+func GetGeneration(id EntityHandle) byte {
 	return byte(id >> GenerationShiftBits)
 }
 
-func GetFlags(id uint64) EntityFlag {
+func GetFlags(id EntityHandle) EntityFlag {
 	return EntityFlag(id >> FlagsShiftBits)
 }
 
-func GetIndex(id uint64) uint64 {
-	return id & IndexBitMask
+func GetIndex(id EntityHandle) uint64 {
+	return uint64(id & IndexBitMask)
 }
 
 func (e *Entity) HasFlag(ef EntityFlag) bool {
 	return GetFlags(e.ID)&ef > 0
 }
 
-func NewEntityId(generation byte, flags EntityFlag, index uint64) uint64 {
-	return index | (uint64(generation) << GenerationShiftBits) | (uint64(flags) << FlagsShiftBits)
+func NewEntityId(generation byte, flags EntityFlag, index uint64) EntityHandle {
+	return EntityHandle(index | (uint64(generation) << GenerationShiftBits) | (uint64(flags) << FlagsShiftBits))
 }

entity/registry.go

@@ -61,7 +61,7 @@ func (r *Registry) NewEntity() *Entity {
 	return entityToUse
 }
 
-func (r *Registry) GetEntity(id uint64) *Entity {
+func (r *Registry) GetEntity(id EntityHandle) *Entity {
 
 	index := GetIndex(id)
 	gen := GetGeneration(id)
@@ -76,13 +76,17 @@ func (r *Registry) GetEntity(id uint64) *Entity {
 	return e
 }
 
-func (r *Registry) FreeEntity(id uint64) {
+func (r *Registry) FreeEntity(id EntityHandle) {
 
 	e := r.GetEntity(id)
 	if e == nil {
 		return
 	}
 
+	for i := 0; i < len(e.Comps); i++ {
+		e.Comps[i].Destroy()
+	}
+
 	r.EntityCount--
 	eIndex := GetIndex(e.ID)