include both!

zig-ecs/src/ecs/groups.zig

@@ -179,8 +179,33 @@ pub const OwningGroup = struct {
             else => std.debug.assert("invalid func"),
         };
 
-        var iter = self.iterator(Components);
-        while (iter.next()) |comps| {
+        // optionally we could just use an Interator here
+        // var iter = self.iterator(Components);
+        // while (iter.next()) |comps| {
+        //     @call(.{ .modifier = .always_inline }, func, .{comps});
+        // }
+
+        const component_info = @typeInfo(Components).Struct;
+
+        // get the data pointers for the chunks
+        var component_ptrs: [component_info.fields.len][*]u8 = undefined;
+        inline for (component_info.fields) |field, i| {
+            const storage = self.registry.assure(field.field_type.Child);
+            component_ptrs[i] = @ptrCast([*]u8, storage.instances.items.ptr);
+        }
+
+        var storage = self.firstOwnedStorage();
+        var index: usize = 0;
+        while (index < self.group_data.current) : (index += 1) {
+            const ent = storage.set.dense.items[index];
+            const entity_index = storage.set.index(ent);
+
+            var comps: Components = undefined;
+            inline for (component_info.fields) |field, i| {
+                const typed_ptr = @ptrCast([*]field.field_type.Child, @alignCast(@alignOf(field.field_type.Child), component_ptrs[i]));
+                @field(comps, field.name) = &typed_ptr[entity_index];
+            }
+
             @call(.{ .modifier = .always_inline }, func, .{comps});
         }
     }