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https://github.com/skaarj1989/entt-meets-sol2
Use EnTT in Lua with Sol2
https://github.com/skaarj1989/entt-meets-sol2
cpp17 ecs entt gamedev lua scripting sol2
Last synced: about 2 months ago
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Use EnTT in Lua with Sol2
- Host: GitHub
- URL: https://github.com/skaarj1989/entt-meets-sol2
- Owner: skaarj1989
- License: cc0-1.0
- Created: 2021-01-05T08:54:35.000Z (about 4 years ago)
- Default Branch: master
- Last Pushed: 2024-11-12T19:36:20.000Z (3 months ago)
- Last Synced: 2024-12-11T02:22:00.410Z (2 months ago)
- Topics: cpp17, ecs, entt, gamedev, lua, scripting, sol2
- Language: C++
- Homepage:
- Size: 260 KB
- Stars: 47
- Watchers: 3
- Forks: 4
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# EnTT meets Sol2
[](https://www.codefactor.io/repository/github/skaarj1989/entt-meets-sol2)
## Requirements
- EnTT v.3.14.0 (latest)
- sol2 v3.2.2 (latest)
## Building
```bash
> git clone https://github.com/skaarj1989/entt-meets-sol2.git
> cd entt-meets-sol2
> cmake -S . -B build
```
### vcpkg quickstart
https://github.com/microsoft/vcpkg#getting-started
```bash
> git clone https://github.com/microsoft/vcpkg
> ./vcpkg/bootstrap-vcpkg.bat
```
Add the following environment variables
```bash
VCPKG_ROOT=path_to_vcpkg
VCPKG_DEFAULT_TRIPLET=x64-windows
```
Install required dependencies
```bash
> ./vcpkg install entt sol2 lua
```
## Registry
[entt/wiki/registry](https://github.com/skypjack/entt/wiki/Crash-Course:-entity-component-system#the-registry-the-entity-and-the-component)
### Goal
- Expose `registry` to Lua scripts:
- Manage entity lifetime
- Set components
- Get component by reference
- `runtime_view`
- Some of **MonoBehaviour** functionality
### c++ setup
[examples/registry](https://github.com/skaarj1989/entt-meets-sol2/blob/main/examples/registry/)
```cpp
struct Transform { int x, y; };
register_meta_component();
sol::state lua{};
lua.require("dispatcher" ...);
lua.new_usertype("Transform",
"type_id", &entt::type_hash::value,
sol::call_constructor,
sol::factories([](int x, int y) {
return Transform{ x, y };
}),
"x", &Transform::x,
"y", &Transform::y
);
```
```cpp
entt::registry registry{};
lua["registry"] = std::ref(registry); // Make the registry available to Lua
```
### Lua script
```lua
-- Create a registry inside a script
registry = entt.registry.new()
```
```lua
mario = registry:create()
registry:emplace(mario, Transform(1, 2))
material = registry:get(mario, Material)
if (registry:has(mario, Transform)) then
registry:emplace(mario, DeletionFlag())
end
```
```lua
-- Utilizes variadic args - pass as many types as you want
registry:runtime_view(Transform, DeletionFlag):each(
function(entity)
registry:remove(entity, DeletionFlag)
end
)
```
Want something like **MonoBehaviour** in Unity?
[examples/system](https://github.com/skaarj1989/entt-meets-sol2/tree/main/examples/system)
### Lua script
```lua
local node = {}
function node:init()
self.owner:emplace(self.id(), Transform(5, 9))
end
function node:update(dt)
local transform = self.owner:get(self.id(), Transform)
transform.x = transform.x + 1
end
function node:destroy()
-- ...
end
return node
```
### c++ setup
```cpp
struct ScriptComponent {
sol::table self;
struct {
sol::function update;
} hooks;
};
registry.emplace(entity, lua.script_file("behavior.lua"));
while (true) {
auto view = registry.view();
for (auto entity : view) {
auto &script = view.get(entity);
script.hooks.update(script.self, delta_time);
}
}
```
## Event dispatcher
[entt/wiki/dispatcher](https://github.com/skypjack/entt/wiki/Crash-Course:-events,-signals-and-everything-in-between#event-dispatcher)
### Goal
- Either create new (inside script) or connect existing (native c++) dispatcher
- Trigger/enqueue events from Lua side
- Listen for events in Lua scripts
- Support disconnection of listeners
### c++ setup
[examples/dispatcher](https://github.com/skaarj1989/entt-meets-sol2/tree/main/examples/dispatcher)
```cpp
struct an_event { int value; };
register_meta_event();
sol::state lua{}
lua.require("dispatcher", ...)
lua.new_usertype("an_event",
"type_id", &entt::type_hash::value,
sol::call_constructor,
sol::factories([](int value) {
return an_event{ value };
}),
"value", &an_event::value
);
```
```cpp
entt::dispatcher dispatcher{};
lua["dispatcher"] = std::ref(dispatcher); // Make the dispatcher available to Lua
// load a script ...
dispatcher.update(); // inside loop
```
### Lua script
```lua
-- Create a dispatcher in a script
dispatcher = entt.dispatcher.new()
```
```lua
listener = {}
function listener.receive(evt)
-- ...
end
function listener.method(evt)
-- ...
end
-- You have to store result of 'connect()', otherwise listener will be
-- disconnected in lua garbage collection step.
conn = dispatcher:connect(an_event, listener.receive)
dispatcher:connect(another_event, listener.method)
-- Event type is deduced from bound 'type_id()' method
dispatcher:trigger(an_event(42))
dispatcher:enqueue(another_event())
conn = nil -- to disconnect listener
```
## Cooperative scheduler
[entt/wiki/cooperative-scheduler](https://github.com/skypjack/entt/wiki/Crash-Course:-cooperative-scheduler)
### Goal
- Define process class in Lua and attach it to `scheduler` either native c++ or dedicated to script
- Allow process chaining
### c++ setup
[examples/scheduler](https://github.com/skaarj1989/entt-meets-sol2/tree/main/examples/scheduler)
```cpp
sol::state lua{};
lua.require("scheduler", ...);
```
```cpp
entt::scheduler scheduler{};
lua["scheduler"] = std::ref(scheduler); // Make the scheduler available to Lua
scheduler.update(dt); // inside loop
```
### Lua script
```lua
-- Create a scheduler in a script
scheduler = entt.scheduler.new()
```
```lua
local process_a = {}
function process:update(dt)
-- ...
end
-- define init, succeeded and other methods ...
-- This one differs from entt attach().then().then ... but works the same
scheduler:attach(
process_a,
process_b,
process_n
-- etc ...
)
```
## License
Code released under [CC0 1.0 Universal](LICENSE)