-
-
Save FollowCD/f9849f325b23f5c9a6e98d13e90464b9 to your computer and use it in GitHub Desktop.
Simple ecs implementation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| local Entity = { | |
| } | |
| local EntityMeta = { | |
| __index = function(entity, key) | |
| local o = rawget(Entity, key) | |
| if(o ~= nil) then | |
| return o | |
| end | |
| local component_id = key | |
| if(type(component_id) == "string") then | |
| component_id = entity:lookup_component_id(key) | |
| if(component_id == nil) then | |
| return nil | |
| end | |
| end | |
| local component_index = entity.component_indices[component_id] | |
| if(component_index ~= nil) then | |
| local components = entity.world.components[component_id] | |
| if(components ~= nil) then | |
| return components[component_index] | |
| end | |
| end | |
| return nil | |
| end | |
| } | |
| function Entity:new(world) | |
| local o = {} | |
| o.world = world | |
| o.component_indices = {} | |
| setmetatable(o, EntityMeta) | |
| return o | |
| end | |
| function Entity:add_component(key, c) | |
| local component_id = key | |
| if(type(component_id) == "string") then | |
| component_id = self:lookup_component_id(component_id) | |
| end | |
| if(component_id == nil) then | |
| return | |
| end | |
| local world = self.world | |
| local components = world.components[component_id] | |
| if(components == nil) then | |
| components = {} | |
| world.components[component_id] = components | |
| end | |
| table.insert(components, c) | |
| local idx = #components | |
| self.component_indices[component_id] = idx | |
| self.mask = self.mask or 0 | |
| self.mask = self.mask | (1 << component_id) | |
| end | |
| function Entity:lookup_component_id(name) | |
| return self.world.component_map[name] | |
| end | |
| local World = { | |
| } | |
| function World:new(o) | |
| local o = o or { | |
| entities = {}, | |
| components = {}, | |
| systems = {}, | |
| component_map = {} | |
| } | |
| setmetatable(o, {__index = World}) | |
| return o | |
| end | |
| function World:new_entity() | |
| local e = Entity:new(self) | |
| table.insert(self.entities, e) | |
| return e | |
| end | |
| function World:add_system(s) | |
| table.insert(self.systems, s) | |
| s.mask = self:generate_mask(s.components) | |
| end | |
| function World:register_components(m) | |
| self.component_map = m | |
| end | |
| function World:generate_mask(components) | |
| local mask = 0 | |
| for i, v in ipairs(components) do | |
| local component_id = self.component_map[v] | |
| if(component_id ~= nil) then | |
| mask = mask | (1 << component_id) | |
| end | |
| end | |
| return mask | |
| end | |
| function World:tick(dT) | |
| for system_idx, system in ipairs(self.systems) do | |
| local entities = {} | |
| for entity_idx, entity in ipairs(self.entities) do | |
| if(system.mask & ~entity.mask == 0) then | |
| table.insert(entities, entity) | |
| end | |
| end | |
| system.tick(entities, dT) | |
| end | |
| end | |
| return { | |
| World = World | |
| } |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| local World = require("ecs").World | |
| local w = World:new() | |
| w:register_components({ | |
| transform = 0, | |
| rotation = 1 | |
| }) | |
| local e1 = w:new_entity() | |
| local e2 = w:new_entity() | |
| e1:add_component("transform", {x = 0, y = 0, z = 9}) | |
| e2:add_component("transform", {x = 0, y = 0, z = 9}) | |
| e2:add_component("rotation", {angle = 0}) | |
| function tick(entities, dT) | |
| for i, e in ipairs(entities) do | |
| e.transform.x = e.transform.x + dT | |
| end | |
| end | |
| local s = { | |
| tick = tick, | |
| components = {"transform", "rotation"} | |
| } | |
| w:add_system(s) | |
| w:tick(0.5) | |
| print(e1.transform.x) | |
| print(e2.transform.x) | |
| w:tick(0.56) | |
| print(e1.transform.x) | |
| print(e2.transform.x) |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment