ECS Framework¶
ECS stands for Entity, Component & System. This is frequently applied pattern in application’s built as a finite state machine, accepting different input driving the system handling.
X-visual is inspired by fritzy/ECS.
Before x-visual v1.0, all object are handled in static way - no new object can be created after scene updating started. Each subsystem is implement assuming that entity won’t been changed during entire rendering life cycle.
It’s true since v0.3 some model loading and assets handling are asynchronous, which means model of texture can be changed after scene started updating. As loading SVG & GLTF asynchronously required, the v0.2.39 can add assets to Three.js later than initializing xworld.
Reason: there are many other more important concepts to be verified, this decision can largely simplify x-visual, and it’s highly probably impose limited modification when it’s needed in the future.
query conditions¶
The query condition of entity set that a system updating upon.
Attention
All these type of conditions are recommended to use only one of it for each query. Any combination of these are not tested and debugged - though it’s designed in this way.
Is it reasonable to suppose that defining components carefully will eliminate the needing of logic combination - no such requirements?
- has
The has query condition is what fritzy provided in the original ECS framework.
In x-visual, this means query entities with all the provided components:
provide c1, c2, c3 are components,
set sys.query = {has: ['c1', 'c2']},
e = {c1, c2}, f = {c1, c2, c3},
ecs.queryEntities() => result = [e]
- iffall
The iffall query condition get entities with all required components if it prestend, no matter any other components in the entity.:
provide c1, c2, c3 are components,
set sys.query = {iffall: ['c1', 'c2']},
e = {c1, c2}, f = {c1, c2, c3},
ecs.queryEntities() => result = [e, f]
- any
The any query condition is will get entities with any of the defined components.:
provide c1, c2, c3 are components,
set sys.query = {any: ['c1', 'c3']},
e = {c1, c2}, f = {c2, c3}, g = {c2}
ecs.queryEntities() => result = [e, f]