treballant en les naus de title

CLAUDE.md

@@ -505,6 +505,284 @@ void dibuixar() {
 }
 ```
 
+## Title Screen Ship System (BETA 3.0)
+
+The title screen features two 3D ships floating on the starfield with perspective rendering, entry/exit animations, and subtle floating motion.
+
+### Architecture Overview
+
+**Files:**
+- `source/game/title/ship_animator.hpp/cpp` - Ship animation state machine
+- `source/core/rendering/shape_renderer.hpp/cpp` - 3D rotation + perspective projection
+- `source/core/defaults.hpp` - Title::Ships namespace with all constants
+- `source/game/escenes/escena_titol.hpp/cpp` - Integration with title scene
+
+**Design Philosophy:**
+- **Static 3D rotation**: Ships have fixed pitch/yaw/roll angles (not recalculated per frame)
+- **Simple Z-axis simulation**: Scale changes simulate depth, not full perspective recalculation
+- **State machine**: ENTERING → FLOATING → EXITING states
+- **Easing functions**: Smooth transitions with ease_out_quad (entry) and ease_in_quad (exit)
+- **Sinusoidal floating**: Organic motion using X/Y oscillation with phase offset
+
+### 3D Rendering System
+
+#### Rotation3D Struct (shape_renderer.hpp)
+
+```cpp
+struct Rotation3D {
+    float pitch;  // X-axis rotation (nose up/down)
+    float yaw;    // Y-axis rotation (turn left/right)
+    float roll;   // Z-axis rotation (bank left/right)
+
+    Rotation3D() : pitch(0.0f), yaw(0.0f), roll(0.0f) {}
+    Rotation3D(float p, float y, float r) : pitch(p), yaw(y), roll(r) {}
+
+    bool has_rotation() const {
+        return pitch != 0.0f || yaw != 0.0f || roll != 0.0f;
+    }
+};
+```
+
+#### 3D Transformation Pipeline (shape_renderer.cpp)
+
+```cpp
+static Punt apply_3d_rotation(float x, float y, const Rotation3D& rot) {
+    float z = 0.0f;  // All 2D points start at Z=0
+
+    // 1. Pitch (X-axis): Rotate around horizontal axis
+    float cos_pitch = std::cos(rot.pitch);
+    float sin_pitch = std::sin(rot.pitch);
+    float y1 = y * cos_pitch - z * sin_pitch;
+    float z1 = y * sin_pitch + z * cos_pitch;
+
+    // 2. Yaw (Y-axis): Rotate around vertical axis
+    float cos_yaw = std::cos(rot.yaw);
+    float sin_yaw = std::sin(rot.yaw);
+    float x2 = x * cos_yaw + z1 * sin_yaw;
+    float z2 = -x * sin_yaw + z1 * cos_yaw;
+
+    // 3. Roll (Z-axis): Rotate around depth axis
+    float cos_roll = std::cos(rot.roll);
+    float sin_roll = std::sin(rot.roll);
+    float x3 = x2 * cos_roll - y1 * sin_roll;
+    float y3 = x2 * sin_roll + y1 * cos_roll;
+
+    // 4. Perspective projection (Z-divide)
+    constexpr float perspective_factor = 500.0f;
+    float scale_factor = perspective_factor / (perspective_factor + z2);
+
+    return {x3 * scale_factor, y3 * scale_factor};
+}
+```
+
+**Rendering order**: 3D rotation → perspective → 2D scale → 2D rotation → translation
+
+**Backward compatibility**: Optional `rotation_3d` parameter (default nullptr) - existing code unaffected
+
+### Ship Animation State Machine
+
+#### States (ship_animator.hpp)
+
+```cpp
+enum class EstatNau {
+    ENTERING,  // Entering from off-screen
+    FLOATING,  // Floating at target position
+    EXITING    // Flying towards vanishing point
+};
+
+struct NauTitol {
+    int jugador_id;              // 1 or 2
+    EstatNau estat;              // Current state
+    float temps_estat;           // Time in current state
+
+    Punt posicio_inicial;        // Start position
+    Punt posicio_objectiu;       // Target position
+    Punt posicio_actual;         // Current interpolated position
+
+    float escala_inicial;        // Start scale
+    float escala_objectiu;       // Target scale
+    float escala_actual;         // Current interpolated scale
+
+    Rotation3D rotacio_3d;       // STATIC 3D rotation (never changes)
+    float fase_oscilacio;        // Oscillation phase accumulator
+
+    std::shared_ptr<Graphics::Shape> forma;
+    bool visible;
+};
+```
+
+#### State Transitions
+
+**ENTERING** (2.0s):
+- Ships appear from beyond screen edges (calculated radially from clock positions)
+- Lerp position: off-screen → target (clock 8 / clock 4)
+- Lerp scale: 1.0 → 0.6 (perspective effect)
+- Easing: `ease_out_quad` (smooth deceleration)
+- Transition: → FLOATING when complete
+
+**FLOATING** (indefinite):
+- Sinusoidal oscillation on X/Y axes
+- Different frequencies (0.5 Hz / 0.7 Hz) with phase offset (π/2)
+- Creates organic circular/elliptical motion
+- Scale constant at 0.6
+- Transition: → EXITING when START pressed
+
+**EXITING** (1.0s):
+- Ships fly towards vanishing point (center: 320, 240)
+- Lerp position: current → vanishing point
+- Lerp scale: current → 0.0 (simulates Z → infinity)
+- Easing: `ease_in_quad` (acceleration)
+- Edge case: If START pressed during ENTERING, ships fly from mid-animation position
+- Marks invisible when complete
+
+### Configuration (defaults.hpp)
+
+```cpp
+namespace Title {
+namespace Ships {
+    // Clock positions (polar coordinates from center 320, 240)
+    constexpr float CLOCK_8_ANGLE = 150.0f * Math::PI / 180.0f;  // Bottom-left
+    constexpr float CLOCK_4_ANGLE = 30.0f * Math::PI / 180.0f;   // Bottom-right
+    constexpr float CLOCK_RADIUS = 150.0f;
+
+    // Target positions (pre-calculated)
+    constexpr float P1_TARGET_X = 190.0f;  // Clock 8
+    constexpr float P1_TARGET_Y = 315.0f;
+    constexpr float P2_TARGET_X = 450.0f;  // Clock 4
+    constexpr float P2_TARGET_Y = 315.0f;
+
+    // 3D rotations (STATIC - tuned for subtle effect)
+    constexpr float P1_PITCH = 0.1f;   // ~6° nose-up
+    constexpr float P1_YAW = -0.15f;   // ~9° turn left
+    constexpr float P1_ROLL = -0.05f;  // ~3° bank left
+
+    constexpr float P2_PITCH = 0.1f;   // ~6° nose-up
+    constexpr float P2_YAW = 0.15f;    // ~9° turn right
+    constexpr float P2_ROLL = 0.05f;   // ~3° bank right
+
+    // Scales
+    constexpr float ENTRY_SCALE_START = 1.0f;
+    constexpr float FLOATING_SCALE = 0.6f;
+
+    // Animation durations
+    constexpr float ENTRY_DURATION = 2.0f;
+    constexpr float EXIT_DURATION = 1.0f;
+    constexpr float ENTRY_OFFSET = 200.0f;  // Distance beyond screen edge
+
+    // Floating oscillation
+    constexpr float FLOAT_AMPLITUDE_X = 6.0f;
+    constexpr float FLOAT_AMPLITUDE_Y = 4.0f;
+    constexpr float FLOAT_FREQUENCY_X = 0.5f;
+    constexpr float FLOAT_FREQUENCY_Y = 0.7f;
+    constexpr float FLOAT_PHASE_OFFSET = 1.57f;  // π/2 (90°)
+
+    // Vanishing point
+    constexpr float VANISHING_POINT_X = 320.0f;
+    constexpr float VANISHING_POINT_Y = 240.0f;
+}
+}
+```
+
+### Integration with EscenaTitol
+
+#### Constructor
+
+```cpp
+// Initialize ships after starfield
+ship_animator_ = std::make_unique<Title::ShipAnimator>(sdl_.obte_renderer());
+ship_animator_->inicialitzar();
+
+if (estat_actual_ == EstatTitol::MAIN) {
+    // Jump to MAIN: ships already in position (no entry animation)
+    ship_animator_->set_visible(true);
+} else {
+    // Normal flow: ships enter during STARFIELD_FADE_IN
+    ship_animator_->set_visible(true);
+    ship_animator_->start_entry_animation();
+}
+```
+
+#### Update Loop
+
+```cpp
+// Update ships in visible states
+if (ship_animator_ &&
+    (estat_actual_ == EstatTitol::STARFIELD_FADE_IN ||
+     estat_actual_ == EstatTitol::STARFIELD ||
+     estat_actual_ == EstatTitol::MAIN ||
+     estat_actual_ == EstatTitol::PLAYER_JOIN_PHASE)) {
+    ship_animator_->actualitzar(delta_time);
+}
+
+// Trigger exit when START pressed
+if (checkStartGameButtonPressed()) {
+    estat_actual_ = EstatTitol::PLAYER_JOIN_PHASE;
+    ship_animator_->trigger_exit_animation();  // Edge case: handles mid-ENTERING
+    Audio::get()->fadeOutMusic(MUSIC_FADE);
+}
+```
+
+#### Draw Loop
+
+```cpp
+// Draw order: starfield → ships → logo → text
+if (starfield_) starfield_->dibuixar();
+
+if (ship_animator_ &&
+    (estat_actual_ == EstatTitol::STARFIELD_FADE_IN ||
+     estat_actual_ == EstatTitol::STARFIELD ||
+     estat_actual_ == EstatTitol::MAIN ||
+     estat_actual_ == EstatTitol::PLAYER_JOIN_PHASE)) {
+    ship_animator_->dibuixar();
+}
+
+// Logo and text drawn after ships (foreground)
+```
+
+### Timing & Visibility
+
+**Timeline:**
+1. **STARFIELD_FADE_IN** (3.0s): Ships enter from off-screen
+2. **STARFIELD** (4.0s): Ships floating
+3. **MAIN** (indefinite): Ships floating + logo + text visible
+4. **PLAYER_JOIN_PHASE** (2.5s): Ships exit (1.0s) + text blink
+5. **BLACK_SCREEN** (2.0s): Ships already invisible (exit completed at 1.0s)
+
+**Automatic visibility management:**
+- Ships marked `visible = false` when exit animation completes (actualitzar_exiting)
+- No manual hiding needed - state machine handles it
+
+### Tuning Notes
+
+**If ships look distorted:**
+- Reduce rotation angles (P1_PITCH, P1_YAW, P1_ROLL, P2_*)
+- Current values (0.1, 0.15, 0.05) are tuned for subtle 3D effect
+- Angles in radians: 0.1 rad ≈ 6°, 0.15 rad ≈ 9°
+
+**If ships are too large/small:**
+- Adjust FLOATING_SCALE (currently 0.6)
+- Adjust ENTRY_SCALE_START (currently 1.0)
+
+**If floating motion is too jerky/smooth:**
+- Adjust FLOAT_AMPLITUDE_X/Y (currently 6.0/4.0 pixels)
+- Adjust FLOAT_FREQUENCY_X/Y (currently 0.5/0.7 Hz)
+
+**If entry/exit animations are too fast/slow:**
+- Adjust ENTRY_DURATION (currently 2.0s)
+- Adjust EXIT_DURATION (currently 1.0s)
+
+### Implementation Phases (Completed)
+
+✅ **Phase 1**: 3D infrastructure (Rotation3D, render_shape extension)
+✅ **Phase 2**: Foundation (ship_animator files, constants)
+✅ **Phase 3**: Configuration & loading (shape loading, initialization)
+✅ **Phase 4**: Floating animation (sinusoidal oscillation)
+✅ **Phase 5**: Entry animation (off-screen → position with easing)
+✅ **Phase 6**: Exit animation (position → vanishing point)
+✅ **Phase 7**: EscenaTitol integration (constructor, update, draw)
+✅ **Phase 8**: Polish & tuning (angles, scales, edge cases)
+✅ **Phase 9**: Documentation (CLAUDE.md, code comments)
+
 ## Migration Progress
 
 ### ✅ Phase 0: Project Setup