Implement faster copy between tables (#420)

Author: mlange-42

CHANGELOG.md

@@ -15,7 +15,7 @@
 - Adds method `World.Shrink` for freeing memory that exceeds current requirements (#323, #417)
 - World lock and filters are concurrency-safe, allowing for concurrent query execution (#360. #405)
 - Adds methods `ObserverX.New`, `Map.New` and `Resource.New` as shortcuts to avoid repeated parameter listing (#393, #394. #395)
-- Adds method `World.CopyEntity` for entity duplication (#415, #418)
+- Adds method `World.CopyEntity` for entity duplication (#415, #418, #420)
 
 ### Performance
 

ecs/table.go

@@ -114,10 +114,11 @@ func (t *table) Set(component ID, index uint32, src *column, srcIndex uint32) {
 	t.components[component.id].Set(index, src, srcIndex)
 }
 
-// Copy the value of a component to the given row index from another index in the same column.
-func (t *table) Copy(component ID, index uint32, srcIndex uint32) {
-	column := t.components[component.id]
-	column.Set(index, column, srcIndex)
+// CopyAll copies all component values from a row of another table with the same layout into this table.
+func (t *table) CopyAll(table *table, index uint32, srcIndex uint32) {
+	for i := range t.columns {
+		t.columns[i].Set(index, &table.columns[i], srcIndex)
+	}
 }
 
 // SetEntity sets the entity at the given row index.
@@ -236,7 +237,7 @@ func (t *table) Reset() {
 	t.len = 0
 }
 
-// AddAll adds all entities with components from another table to this table.
+// AddAll adds all entities with components from another table with the same layout to this table.
 func (t *table) AddAll(from *table, count uint32) {
 	t.Alloc(count)
 	t.entities.CopyToEnd(&from.entities, t.len, count)

ecs/world.go

@@ -102,9 +102,8 @@ func (w *World) CopyEntity(e Entity) Entity {
 
 	archetype := &s.archetypes[table.archetype]
 
-	for _, id := range archetype.components {
-		table.Copy(id, idx, index.row)
-	}
+	table.CopyAll(table, idx, index.row)
+
 	w.storage.observers.FireCreateEntityIfHas(entity, &archetype.mask)
 	return entity
 }

ecs/world_internal.go

@@ -394,9 +394,7 @@ func (w *World) setRelations(entity Entity, relations []relationID) {
 
 	newIndex := newTable.Add(entity)
 
-	for _, id := range oldArch.components {
-		newTable.Set(id, newIndex, oldTable.Column(id), index.row)
-	}
+	newTable.CopyAll(oldTable, newIndex, index.row)
 
 	swapped := oldTable.Remove(index.row)