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Lua ECS
local core = require "ecs.core"
local ecs = {}
local entities = {} -- all Entities, eid -> entity
local entity_id = 0
ecs.entities = entities
-- cset: component set
local cset = { __mode = "kv" }
-- cctypes: C component type
local cctypes = {}
-- ctype: component type
local ctypes = { _typeid = 0 }
setmetatable(ctypes, ctypes)
function ctypes:__index(newtype)
local typeid = self._typeid + 1
assert(typeid < 0xffff)
self._typeid = typeid
self[newtype] = typeid
self[typeid] = newtype
return typeid
end
function ecs.register_type(newtype)
local ctype = assert(newtype.typename)
local cnew = assert(newtype.new)
local cdel = assert(newtype.del)
assert(rawget(ctypes, ctype) == nil, "Register ctype first")
local typeid = ctypes[ctype]
assert(cctypes[typeid] == nil, "Already register ctype")
cctypes[typeid] = { new = cnew, del = cdel }
end
-- etype: entity type
local etypes = { __mode = "kv" }
setmetatable(etypes, etypes)
function etypes:__index(typekey)
local info = {}
local n = #typekey
for i = 1, n, 2 do
local typeid = string.unpack("H",typekey,i)
local c = cctypes[typeid]
if c then
info[ctypes[typeid]] = c.del
else
info[ctypes[typeid]] = false
end
end
self[typekey] = info
return info
end
function ecs.new_entity()
local e = { _type = "" }
entity_id = entity_id + 1
entities[entity_id] = e
return entity_id
end
function ecs.delete_entity(eid)
local e = assert(entities[eid])
local typeinfo = etypes[e._type]
for typename, del in pairs(typeinfo) do
if del then
del(e[typename])
e[typename] = nil
end
end
entities[eid] = nil
end
function ecs.new_component(eid, ctype)
local e = assert(entities[eid])
local typeid = ctypes[ctype]
e._type = core.add_component(e._type, typeid)
local set = cset[ctype]
if set then
set[#set + 1] = eid
end
local c = cctypes[typeid]
if c then
local obj = c.new(eid)
e[ctype] = obj
return obj
else
return e
end
end
function ecs.component(eid, ctype)
local e = assert(entities[eid])
local typeinfo = etypes[e._type]
local c = typeinfo[ctype]
if c ~= nil then
if c then
return e[ctype]
else
return e
end
end
end
function ecs.set(ctype)
local s = cset[ctype]
if s == nil then
s = {}
for eid, e in pairs(entities) do
local typeinfo = etypes[e._type]
local c = typeinfo[ctype]
if c ~= nil then
s[#s+1] = eid
end
end
cset[ctype] = s
end
return s
end
-- Lua Version
--local function component_next(set, index)
-- local n = #set
-- index = index + 1
-- while index <= n do
-- local eid = set[index]
-- local e = entities[eid]
-- if e then
-- return index, e
-- end
-- set[index] = set[n]
-- set[n] = nil
-- n = n - 1
-- end
--end
-- C Version
local component_next = core.component_next(entities)
function ecs.ipairs(ctype)
return component_next, ecs.set(ctype), 0
end
-- Iterator
function ecs.components(eid)
local e = assert(entities[eid])
return next, etypes[e._type], nil
end
return ecs
--[[
#define LUA_LIB
#include <lua.h>
#include <lauxlib.h>
#include <stdint.h>
static int
ladd_component(lua_State *L) {
size_t sz;
const uint16_t *t = (const uint16_t *)luaL_checklstring(L, 1, &sz);
uint16_t typeid = (uint16_t)luaL_checkinteger(L, 2);
luaL_Buffer b;
uint16_t * buff = (uint16_t *)luaL_buffinitsize(L, &b, sz+2);
int i;
int n = (int)sz / 2;
for (i=0;i<n;i++) {
if (typeid < t[i])
break;
if (typeid == t[i]) {
return luaL_error(L, "Duplicate component %d", typeid);
}
buff[i] = t[i];
}
buff[i] = typeid;
for (;i<n;i++) {
buff[i+1] = t[i];
}
luaL_addsize(&b, sz+2);
luaL_pushresult(&b);
return 1;
}
static int
lnext(lua_State *L) {
int n = lua_rawlen(L, 1);
int index = luaL_checkinteger(L, 2) + 1;
while (index <= n) {
lua_rawgeti(L, 1, index);
int eid = lua_tointeger(L, -1);
if (lua_rawgeti(L, lua_upvalueindex(1), eid) == LUA_TTABLE) {
lua_pushinteger(L, index);
lua_replace(L, -3);
return 2;
} else {
lua_pop(L, 2);
lua_rawgeti(L, 1, n);
lua_rawseti(L, 1, index);
lua_pushnil(L);
lua_rawseti(L, 1, n);
--n;
}
}
return 0;
}
static int
lcomponent_next(lua_State *L) {
luaL_checktype(L, 1, LUA_TTABLE);
lua_pushcclosure(L, lnext, 1);
return 1;
}
LUAMOD_API int
luaopen_ecs_core(lua_State *L) {
luaL_checkversion(L);
luaL_Reg l[] = {
{ "add_component", ladd_component },
{ "component_next", lcomponent_next },
{ NULL, NULL },
};
luaL_newlib(L, l);
return 1;
}
]]
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