---
name: engine_smoke
lang: cpp
domain: gamedev
version: 0.1.0
description: "Smoke test del stack gamedev: SDL3 + sokol_gfx + Dear ImGui. Valida que el stack compila y corre en PC (Linux/Windows desktop GL) y WASM (WebGL2 via emscripten) antes de invertir tiempo en runtime real (issue 0072a)."
tags: [imgui, sdl3, sokol, gamedev, smoke, wasm]
uses_functions: []
uses_types: []
framework: "imgui"
entry_point: "main.cpp"
dir_path: "apps/engine_smoke"
repo_url: ""
icon:
  phosphor: "game-controller"
  accent: "#16a34a"
e2e_checks:
  - id: build_pc
    cmd: "cmake --build build --target engine_smoke -j"
    timeout_s: 300
  - id: smoke_self
    cmd: "timeout 5 ./build/cpp/apps/engine_smoke/engine_smoke || test $? = 124"
    timeout_s: 10
    severity: warning  # requires display in CI; warning, not critical
  - id: build_wasm
    cmd: "bash bash/functions/pipelines/build_wasm_cpp_app.sh engine_smoke"
    timeout_s: 600
    severity: warning  # requires emsdk
  - id: wasm_size_budget
    cmd: "test -f build/wasm/engine_smoke/engine_smoke.wasm.gz && test $(stat -c%s build/wasm/engine_smoke/engine_smoke.wasm.gz) -lt 1572864"
    severity: warning
---

# engine_smoke

Primer experimento del stack gamedev (issue [0072a](../../../dev/issues/0072a-gamedev-smoke-sdl3-sokol-imgui.md)).

## Que hace

1. Abre ventana SDL3 1280x720 con context OpenGL.
2. Inicializa `sokol_gfx` sobre ese context (GL 3.3 desktop, GLES3 en WASM).
3. Pinta un fullscreen triangle con un fragment shader animado (gradient time-based).
4. Pinta sobre eso un panel ImGui con FPS, tamaño de ventana y boton Quit.

Sin `fn_framework`, sin `add_imgui_app()`. CMakeLists standalone para evitar contaminar el shell desktop hasta validar el stack.

## Build PC (Linux)

Desde la raiz del fn_registry:

```bash
cmake -S cpp -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build --target engine_smoke -j
./build/cpp/apps/engine_smoke/engine_smoke
```

## Build WASM

Requiere `emsdk` instalado y activado en el shell. Ver `cpp/vendor/sokol.VENDORING.md` y `bash/functions/pipelines/build_wasm_cpp_app.sh`.

```bash
bash bash/functions/pipelines/build_wasm_cpp_app.sh engine_smoke
# Sirve build/wasm/engine_smoke/engine_smoke.html en navegador
```

Budget objetivo: gzip ≤ 1.5 MB.

## Stack vendoreado

- `cpp/vendor/sdl3/` — SDL3 release-3.4.8
- `cpp/vendor/sokol/` — sokol_gfx single-header pinned commit
- `cpp/vendor/imgui/` — ImGui 1.92.7 con backends `imgui_impl_sdl3` + `imgui_impl_opengl3`

## Notas de implementacion

- Fullscreen tri via `gl_VertexID` (3 vertices, no VBO). Cubre todo el viewport sin atributos.
- Uniform `u_time` actualizado por frame.
- Backend ImGui = `imgui_impl_opengl3` (oficial, 0 LoC custom). Compatible WebGL2 emscripten.
- `SOKOL_GLCORE` desktop / `SOKOL_GLES3` web — selccion compile-time.
- `setup_gfx` se llama UNA VEZ tras crear el GL context. `sg_setup` toma `sglue_environment()` que lee el contexto activo.

## No-objetivos (smoke)

- No texturas reales (eso entra en 0072b).
- No audio.
- No input game-style.
- No fn_framework integration.
- No mobile (Android/iOS son issues 0072g/h).


## Capability growth log

Una linea por bump SemVer. Bump-type segun `.claude/commands/version.md`:
- `major`: breaking observable (CLI args, schema BBDD propia, formato wire).
- `minor`: feature aditiva (nuevo panel, endpoint, opcion).
- `patch`: bugfix sin cambio observable.

- v0.1.0 (2026-05-18) — baseline.