feat(postfx): debug HUD mostra PostFX, overrides persistents al ciclar, --postfx sense valor

- HUD (F1) afegeix línia PostFX: OFF o PostFX: <preset> [V:x.xx C:x.xx S:x.xx]
- applyPostFXPreset reaaplica overrides de CLI per preservar-los en ciclar amb X
- setPostFXParamOverrides guarda els valors en membres privats per persistència
- --postfx sense valor ja no dona error i utilitza complet (preset 3) per defecte

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

source/engine.cpp

@@ -1053,6 +1053,9 @@ void Engine::applyPostFXPreset(int mode) {
     postfx_uniforms_.vignette_strength = presets[mode][0];
     postfx_uniforms_.chroma_strength   = presets[mode][1];
     postfx_uniforms_.scanline_strength = presets[mode][2];
+    // Reaplicar overrides de CLI si están activos
+    if (postfx_override_vignette_ >= 0.f) postfx_uniforms_.vignette_strength = postfx_override_vignette_;
+    if (postfx_override_chroma_   >= 0.f) postfx_uniforms_.chroma_strength   = postfx_override_chroma_;
 }
 
 void Engine::handlePostFXCycle() {
@@ -1089,6 +1092,15 @@ void Engine::setInitialPostFX(int mode) {
     applyPostFXPreset(mode);
 }
 
+void Engine::setPostFXParamOverrides(float vignette, float chroma) {
+    postfx_override_vignette_ = vignette;
+    postfx_override_chroma_   = chroma;
+    postfx_enabled_ = true;
+    // Aplicar inmediatamente sobre el preset activo
+    if (vignette >= 0.f) postfx_uniforms_.vignette_strength = vignette;
+    if (chroma   >= 0.f) postfx_uniforms_.chroma_strength   = chroma;
+}
+
 void Engine::toggleIntegerScaling() {
     // Ciclar entre los 3 modos: INTEGER → LETTERBOX → STRETCH → INTEGER
     switch (current_scaling_mode_) {

source/engine.hpp

@@ -80,6 +80,7 @@ class Engine {
         void handlePostFXCycle();
         void handlePostFXToggle();
         void setInitialPostFX(int mode);
+        void setPostFXParamOverrides(float vignette, float chroma);
 
         // Modo kiosko
         void setKioskMode(bool enabled) { kiosk_mode_ = enabled; }
@@ -124,6 +125,11 @@ class Engine {
         int getBaseScreenHeight() const { return base_screen_height_; }
         int getMaxAutoScenario() const { return max_auto_scenario_; }
         size_t getCurrentTextureIndex() const { return current_texture_index_; }
+        bool  isPostFXEnabled()    const { return postfx_enabled_; }
+        int   getPostFXMode()      const { return postfx_effect_mode_; }
+        float getPostFXVignette()  const { return postfx_uniforms_.vignette_strength; }
+        float getPostFXChroma()    const { return postfx_uniforms_.chroma_strength; }
+        float getPostFXScanline()  const { return postfx_uniforms_.scanline_strength; }
 
     private:
         // === Componentes del sistema (Composición) ===
@@ -175,6 +181,8 @@ class Engine {
         PostFXUniforms postfx_uniforms_ = {0.0f, 0.0f, 0.0f, 0.0f};
         int postfx_effect_mode_ = 0;
         bool postfx_enabled_ = false;
+        float postfx_override_vignette_ = -1.f;  // -1 = sin override
+        float postfx_override_chroma_   = -1.f;
 
         // Sistema de zoom dinámico
         int current_window_zoom_ = DEFAULT_WINDOW_ZOOM;

source/main.cpp

@@ -21,7 +21,9 @@ 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 << "  --postfx [efecto]    Arrancar con PostFX activo (default: complet): vinyeta, scanlines, cromatica, complet\n";
+    std::cout << "  --vignette <float>   Sobreescribir vignette_strength (activa PostFX si no hay --postfx)\n";
+    std::cout << "  --chroma <float>     Sobreescribir chroma_strength   (activa PostFX si no hay --postfx)\n";
     std::cout << "  --help               Mostrar esta ayuda\n\n";
     std::cout << "Ejemplos:\n";
     std::cout << "  vibe3_physics                    # 320x240 zoom 3 (ventana 960x720)\n";
@@ -47,6 +49,8 @@ int main(int argc, char* argv[]) {
     bool skip_benchmark = false;
     int max_balls_override = 0;
     int initial_postfx = -1;
+    float override_vignette = -1.f;
+    float override_chroma = -1.f;
     AppMode initial_mode = AppMode::SANDBOX;  // Modo inicial (default: SANDBOX)
 
     // Parsear argumentos
@@ -127,7 +131,8 @@ 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) {
+            // Si no hay valor o el siguiente arg es otra opción, defaultear a complet
+            if (i + 1 < argc && argv[i + 1][0] != '-') {
                 std::string fx = argv[++i];
                 if (fx == "vinyeta") {
                     initial_postfx = 0;
@@ -142,7 +147,20 @@ int main(int argc, char* argv[]) {
                     return -1;
                 }
             } else {
-                std::cerr << "Error: --postfx requiere un valor\n";
+                initial_postfx = 3;  // default: complet
+            }
+        } else if (strcmp(argv[i], "--vignette") == 0) {
+            if (i + 1 < argc) {
+                override_vignette = (float)atof(argv[++i]);
+            } else {
+                std::cerr << "Error: --vignette requiere un valor\n";
+                return -1;
+            }
+        } else if (strcmp(argv[i], "--chroma") == 0) {
+            if (i + 1 < argc) {
+                override_chroma = (float)atof(argv[++i]);
+            } else {
+                std::cerr << "Error: --chroma requiere un valor\n";
                 return -1;
             }
         } else if (strcmp(argv[i], "--max-balls") == 0) {
@@ -182,6 +200,12 @@ int main(int argc, char* argv[]) {
     if (initial_postfx >= 0)
         engine.setInitialPostFX(initial_postfx);
 
+    if (override_vignette >= 0.f || override_chroma >= 0.f) {
+        if (initial_postfx < 0)
+            engine.setInitialPostFX(0);
+        engine.setPostFXParamOverrides(override_vignette, override_chroma);
+    }
+
     if (!engine.initialize(width, height, zoom, fullscreen, initial_mode)) {
         std::cout << "¡Error al inicializar el engine!" << std::endl;
         return -1;

source/ui/ui_manager.cpp

@@ -335,6 +335,23 @@ void UIManager::renderDebugHUD(const Engine* engine,
     lines.push_back(logic_res_text);
     lines.push_back(refresh_text);
     lines.push_back(theme_text);
+    std::string postfx_text;
+    if (!engine->isPostFXEnabled()) {
+        postfx_text = "PostFX: OFF";
+    } else {
+        static constexpr const char* preset_names[4] = {
+            "Vinyeta", "Scanlines", "Cromatica", "Complet"
+        };
+        int mode = engine->getPostFXMode();
+        char buf[64];
+        SDL_snprintf(buf, sizeof(buf), "PostFX: %s [V:%.2f C:%.2f S:%.2f]",
+                     preset_names[mode],
+                     engine->getPostFXVignette(),
+                     engine->getPostFXChroma(),
+                     engine->getPostFXScanline());
+        postfx_text = buf;
+    }
+    lines.push_back(postfx_text);
     lines.push_back(elapsed_text);
 
     const Ball* first_ball = scene_manager->getFirstBall();