feat(postfx): redisseny sistema PostFX (X/F5/F6, --postfx CLI)

- X cicla 4 efectes (Vinyeta/Scanlines/Cromàtica/Complet), sempre activa PostFX
- F5 fa toggle PostFX on/off mantenint l'efecte seleccionat
- F6 hereta el toggle d'integer scaling (abans F5)
- Arrencada per defecte sense postprocés (tot a 0)
- --postfx <vinyeta|scanlines|cromatica|complet> per activar des de CLI

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

source/engine.cpp

@@ -1013,23 +1013,52 @@ void Engine::toggleRealFullscreen() {
     }
 }
 
+void Engine::applyPostFXPreset(int mode) {
+    static constexpr float presets[4][3] = {
+        {1.5f, 0.0f, 0.0f},  // 0: Vinyeta
+        {1.5f, 0.0f, 0.8f},  // 1: Scanlines
+        {1.5f, 1.0f, 0.0f},  // 2: Cromàtica
+        {1.5f, 1.0f, 0.8f},  // 3: Complet
+    };
+    postfx_uniforms_.vignette_strength = presets[mode][0];
+    postfx_uniforms_.chroma_strength   = presets[mode][1];
+    postfx_uniforms_.scanline_strength = presets[mode][2];
+}
+
 void Engine::handlePostFXCycle() {
-    static constexpr float presets[5][3] = {
+    static constexpr const char* names[4] = {
-        {1.5f, 0.0f, 0.0f}, {1.5f, 0.0f, 0.8f},
-        {1.5f, 1.0f, 0.0f}, {1.5f, 1.0f, 0.8f},
-        {0.0f, 0.0f, 0.0f}
-    };
-    static constexpr const char* names[5] = {
         "PostFX: Vinyeta", "PostFX: Scanlines",
-        "PostFX: Cromàtica", "PostFX: Complet", "PostFX: Desactivat"
+        "PostFX: Cromàtica", "PostFX: Complet"
     };
-    postfx_effect_mode_ = (postfx_effect_mode_ + 1) % 5;
+    postfx_effect_mode_ = (postfx_effect_mode_ + 1) % 4;
-    postfx_uniforms_.vignette_strength = presets[postfx_effect_mode_][0];
+    postfx_enabled_ = true;
-    postfx_uniforms_.chroma_strength   = presets[postfx_effect_mode_][1];
+    applyPostFXPreset(postfx_effect_mode_);
-    postfx_uniforms_.scanline_strength = presets[postfx_effect_mode_][2];
     showNotificationForAction(names[postfx_effect_mode_]);
 }
 
+void Engine::handlePostFXToggle() {
+    static constexpr const char* names[4] = {
+        "PostFX: Vinyeta", "PostFX: Scanlines",
+        "PostFX: Cromàtica", "PostFX: Complet"
+    };
+    postfx_enabled_ = !postfx_enabled_;
+    if (postfx_enabled_) {
+        applyPostFXPreset(postfx_effect_mode_);
+        showNotificationForAction(names[postfx_effect_mode_]);
+    } else {
+        postfx_uniforms_.vignette_strength = 0.0f;
+        postfx_uniforms_.chroma_strength   = 0.0f;
+        postfx_uniforms_.scanline_strength = 0.0f;
+        showNotificationForAction("PostFX: Desactivat");
+    }
+}
+
+void Engine::setInitialPostFX(int mode) {
+    postfx_effect_mode_ = mode;
+    postfx_enabled_ = true;
+    applyPostFXPreset(mode);
+}
+
 void Engine::toggleIntegerScaling() {
     // Solo permitir cambio si estamos en modo fullscreen normal (F3)
     if (!fullscreen_enabled_) {

source/engine.hpp

@@ -78,6 +78,8 @@ class Engine {
 
         // PostFX presets
         void handlePostFXCycle();
+        void handlePostFXToggle();
+        void setInitialPostFX(int mode);
 
         // Modo kiosko
         void setKioskMode(bool enabled) { kiosk_mode_ = enabled; }
@@ -170,8 +172,9 @@ class Engine {
         float delta_time_ = 0.0f;
 
         // PostFX uniforms (passed to GPU each frame)
-        PostFXUniforms postfx_uniforms_ = {1.5f, 0.0f, 0.0f, 0.0f};
+        PostFXUniforms postfx_uniforms_ = {0.0f, 0.0f, 0.0f, 0.0f};
         int postfx_effect_mode_ = 0;
+        bool postfx_enabled_ = false;
 
         // Sistema de zoom dinámico
         int current_window_zoom_ = DEFAULT_WINDOW_ZOOM;
@@ -244,6 +247,9 @@ class Engine {
         void updateShape();
         void generateShape();
 
+        // PostFX helper
+        void applyPostFXPreset(int mode);
+
         // GPU helpers
         bool loadGpuSpriteTexture(size_t index);   // Upload one sprite texture to GPU
         void recreateOffscreenTexture();            // Recreate when resolution changes

source/input/input_handler.cpp

@@ -254,8 +254,13 @@ bool InputHandler::processEvents(Engine& engine) {
                     else engine.toggleRealFullscreen();
                     break;
 
-                // Toggle escalado entero/estirado (solo en fullscreen F3)
+                // Toggle PostFX activo/inactivo
                 case SDLK_F5:
+                    engine.handlePostFXToggle();
+                    break;
+
+                // Toggle escalado entero/estirado (solo en fullscreen F3)
+                case SDLK_F6:
                     engine.toggleIntegerScaling();
                     break;
 

source/main.cpp

@@ -21,6 +21,7 @@ void printHelp() {
     std::cout << "  --custom-balls <n>   Activa escenario custom (tecla 9) con N pelotas\n";
     std::cout << "  --skip-benchmark     Salta el benchmark y usa el máximo de bolas (50000)\n";
     std::cout << "  --max-balls <n>      Limita el máximo de bolas en modos DEMO/DEMO_LITE\n";
+    std::cout << "  --postfx <efecto>    Arrancar con PostFX activo: vinyeta, scanlines, cromatica, complet\n";
     std::cout << "  --help               Mostrar esta ayuda\n\n";
     std::cout << "Ejemplos:\n";
     std::cout << "  vibe3_physics                    # 320x240 zoom 3 (ventana 960x720)\n";
@@ -45,6 +46,7 @@ int main(int argc, char* argv[]) {
     bool kiosk_mode = false;
     bool skip_benchmark = false;
     int max_balls_override = 0;
+    int initial_postfx = -1;
     AppMode initial_mode = AppMode::SANDBOX;  // Modo inicial (default: SANDBOX)
 
     // Parsear argumentos
@@ -124,6 +126,25 @@ int main(int argc, char* argv[]) {
             }
         } else if (strcmp(argv[i], "--skip-benchmark") == 0) {
             skip_benchmark = true;
+        } else if (strcmp(argv[i], "--postfx") == 0) {
+            if (i + 1 < argc) {
+                std::string fx = argv[++i];
+                if (fx == "vinyeta") {
+                    initial_postfx = 0;
+                } else if (fx == "scanlines") {
+                    initial_postfx = 1;
+                } else if (fx == "cromatica") {
+                    initial_postfx = 2;
+                } else if (fx == "complet") {
+                    initial_postfx = 3;
+                } else {
+                    std::cerr << "Error: --postfx '" << fx << "' no válido. Usa: vinyeta, scanlines, cromatica, complet\n";
+                    return -1;
+                }
+            } else {
+                std::cerr << "Error: --postfx requiere un valor\n";
+                return -1;
+            }
         } else if (strcmp(argv[i], "--max-balls") == 0) {
             if (i + 1 < argc) {
                 int n = atoi(argv[++i]);
@@ -158,6 +179,9 @@ int main(int argc, char* argv[]) {
     else if (skip_benchmark)
         engine.setSkipBenchmark();
 
+    if (initial_postfx >= 0)
+        engine.setInitialPostFX(initial_postfx);
+
     if (!engine.initialize(width, height, zoom, fullscreen, initial_mode)) {
         std::cout << "¡Error al inicializar el engine!" << std::endl;
         return -1;