173 lines
5.5 KiB
Markdown
173 lines
5.5 KiB
Markdown
---
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id: "0072a"
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title: "gamedev — smoke SDL3 + sokol_gfx + ImGui (PC + WASM)"
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status: pendiente
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type: feature
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domain:
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- cpp-stack
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- gamedev
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scope: multi-app
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priority: alta
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depends: []
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blocks: []
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related: []
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created: 2026-05-10
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updated: 2026-05-17
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tags:
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- gamedev
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- cpp
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- wasm
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---
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## Objetivo
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Validar de forma temprana que el stack SDL3 + sokol_gfx + Dear ImGui compila y corre en PC (Windows + Linux) y WASM (Emscripten) con un binario "Hello sprite + shader" antes de invertir tiempo en runtime real.
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## Salida esperada
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App `cpp/apps/engine_smoke/` que:
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1. Abre ventana SDL3 (1280x720, redimensionable).
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2. Inicializa sokol_gfx (GL en desktop, WebGL2 en WASM).
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3. Pinta:
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- Un quad con textura cargada via `stbi_load` (ya en stack).
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- Un fullscreen shader (gradiente animado).
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- Un panel ImGui con FPS y boton "exit".
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4. Compila a:
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- `engine_smoke.exe` (Windows, MSVC o MinGW)
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- `engine_smoke` (Linux, gcc/clang)
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- `engine_smoke.html` + `engine_smoke.wasm` + `engine_smoke.js` (Emscripten)
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5. WASM gzip ≤ **1.5 MB** (objetivo agresivo de Fase 0). Si no se cumple, documentar de donde viene el peso y plan de reduccion.
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## Tareas
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### 1. Vendoring de dependencias
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`cpp/vendor/` ya existe. Añadir:
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- `sokol/` — `sokol_gfx.h`, `sokol_app.h` NO (usamos SDL3), `sokol_log.h`, `sokol_glue.h` adaptado para SDL3 (init manual del contexto).
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- `sdl3/` — clonar build estatico de SDL 3.x.
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- ImGui ya esta en `cpp/vendor/imgui/`. Añadir backends `imgui_impl_sdl3.cpp` + `imgui_impl_sokol.cpp`. Si no existe oficial sokol backend, escribir uno minimo (~200 lineas).
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### 2. CMake
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```cmake
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# cpp/apps/engine_smoke/CMakeLists.txt
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add_executable(engine_smoke main.cpp)
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target_link_libraries(engine_smoke PRIVATE SDL3::SDL3 imgui)
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target_compile_definitions(engine_smoke PRIVATE SOKOL_GLCORE)
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if(EMSCRIPTEN)
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target_link_options(engine_smoke PRIVATE
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-sUSE_WEBGL2=1
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-sFULL_ES3=1
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-sALLOW_MEMORY_GROWTH=1
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-sINITIAL_MEMORY=33554432 # 32MB
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--shell-file=${CMAKE_CURRENT_SOURCE_DIR}/shell.html
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)
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endif()
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```
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NO usar `add_imgui_app` (esa macro asume GLFW + framework desktop). Esta app es deliberadamente standalone para no contaminar `fn_framework` hasta que validemos el stack.
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### 3. main.cpp minimo
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```cpp
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#include <SDL3/SDL.h>
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#define SOKOL_IMPL
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#include "sokol_gfx.h"
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#include "imgui.h"
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#include "imgui_impl_sdl3.h"
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#include "imgui_impl_sokol.h"
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int main(int, char**) {
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SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO);
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SDL_Window* win = SDL_CreateWindow("engine_smoke", 1280, 720,
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SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
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SDL_GLContext ctx = SDL_GL_CreateContext(win);
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sg_setup({ .environment = sokol_glue_env() });
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ImGui::CreateContext();
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ImGui_ImplSDL3_InitForOpenGL(win, ctx);
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ImGui_ImplSokol_Init();
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bool running = true;
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while (running) {
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SDL_Event e;
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while (SDL_PollEvent(&e)) {
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ImGui_ImplSDL3_ProcessEvent(&e);
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if (e.type == SDL_EVENT_QUIT) running = false;
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}
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// render: clear, sprite quad, fullscreen shader, ImGui overlay
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sg_begin_pass({ .swapchain = sokol_glue_swapchain() });
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// ... pipeline + draw calls
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ImGui_ImplSokol_NewFrame();
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ImGui_ImplSDL3_NewFrame();
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ImGui::NewFrame();
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ImGui::Begin("Smoke"); ImGui::Text("FPS: %.1f", ImGui::GetIO().Framerate);
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if (ImGui::Button("exit")) running = false;
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ImGui::End();
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ImGui::Render();
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ImGui_ImplSokol_RenderDrawData(ImGui::GetDrawData());
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sg_end_pass();
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sg_commit();
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SDL_GL_SwapWindow(win);
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}
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sg_shutdown();
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return 0;
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}
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```
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### 4. Shell HTML para WASM
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`shell.html` minimo: canvas + loader. Sin Bootstrap, sin nada extra. Ver Emscripten template default y stripear.
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### 5. Pipeline de build
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Funcion bash nueva: `bash/functions/pipelines/build_wasm_cpp_app.sh` que:
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1. Verifica `emcc` instalado (descarga `emsdk` si falta).
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2. `emcmake cmake -B build/wasm -S cpp/apps/engine_smoke`
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3. `cmake --build build/wasm --target engine_smoke`
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4. Reporta tamaños raw + gzip de `.wasm`, `.js`, `.html`.
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5. Falla si supera budget.
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### 6. e2e_checks en `app.md`
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```yaml
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e2e_checks:
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- id: build_pc
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cmd: "cmake --build build --target engine_smoke -j"
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timeout_s: 300
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- id: build_wasm
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cmd: "bash bash/functions/pipelines/build_wasm_cpp_app.sh engine_smoke"
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timeout_s: 600
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- id: size_budget_wasm
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cmd: "test $(stat -c%s build/wasm/engine_smoke.wasm.gz) -lt 1572864" # 1.5 MB
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```
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## Decisiones a documentar
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- ¿`sokol_gfx` o usar GL directo? — sokol_gfx, abstrae backend mobile despues sin tocar codigo de juego.
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- ¿`sokol_app` o `SDL3` para windowing? — SDL3, mejor soporte mobile + audio + gamepad.
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- ¿Imgui-sokol backend oficial? — verificar `floooh/sokol-samples` repo. Si no, escribirlo (renderable en una sesion, ~200 LoC).
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## Criterio de exito
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- [x] Compila en Linux + Windows (MSVC).
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- [x] Compila en WASM con emscripten ≥3.1.50.
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- [x] WASM gzip ≤ 1.5 MB.
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- [x] Sprite + shader + ImGui visibles en navegador (Chrome + Firefox).
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- [x] FPS estable ≥60 en navegador moderno.
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## Riesgos
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- Backend ImGui+sokol — si no hay oficial, escribir uno (no bloqueante).
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- SDL3 still relativamente nuevo (release oct 2024). Si bugs gordos, fallback a SDL2.
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- Emscripten + sokol_gfx WebGL2 — verificado en `floooh/sokol-samples`, debe funcionar.
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## No-objetivos (Fase 0)
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- NO audio funcional aun.
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- NO touch input.
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- NO build mobile (Android/iOS).
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- NO integracion con `fn_framework`.
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- NO assets reales.
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