ref

• https://github.com/SanderMertens/ecs-faq
• https://ajmmertens.medium.com/building-an-ecs-storage-in-pictures-642b8bfd6e04
• https://ajmmertens.medium.com/building-an-ecs-1-where-are-my-entities-and-components-63d07c7da742
• https://ajmmertens.medium.com/building-an-ecs-2-archetypes-and-vectorization-fe21690805f9
• https://indiegamedev.net/2020/05/19/an-entity-component-system-with-data-locality-in-cpp/
• https://austinmorlan.com/posts/entity_component_system/
• (unfinished) https://makeitshaded.github.io/make-an-ecs/
• http://gameprogrammingpatterns.com/component.html