feat(ship-3d): look-at dinàmic, naus alineades amb el path (punta+cul)

source/game/title/ship_animator3d.cpp

@@ -18,12 +18,6 @@ namespace Title {
         // 0.0F → emet només la silueta plana. >0 emet volum extrudit.
         constexpr float SHIP_EXTRUSION_DEPTH = 1.0F;
 
-        // Rotació pitch que aplica el draw() per orientar la silueta cap al punt
-        // de fuga: el Y2D negatiu del shape (la punta) passa a +Z mundial.
-        // Inclinem ~30° més enllà de -π/2 perquè el "cul" baixe i la punta puje;
-        // així la càmera (a Y=0, una mica per damunt de les naus) veu el dors.
-        constexpr float SHIP_PITCH_RAD = -2.0944F;  // -120°
-
         // Posicions en l'espai 3D (càmera a (0,0,0) mirant cap a +Z, Y cap amunt).
         constexpr float SHIP_FLOAT_X = 25.0F;  // Separació horitzontal
         constexpr float SHIP_FLOAT_Y = -8.0F;  // Lleugerament per davall del centre
@@ -37,6 +31,43 @@ namespace Title {
         // Posició de fuga (al fons, centre projectat).
         constexpr float SHIP_EXIT_Z = 800.0F;
 
+        // Punt cap a on apunten les naus durant FLOATING i EXITING (centre lluny).
+        constexpr Vec3 VANISHING_POINT{.x = 0.0F, .y = 0.0F, .z = SHIP_EXIT_Z};
+
+        // Look-at: calcula pitch+yaw que duen (0,-1,0) local a forward_dir mundial.
+        // Requereix l'ordre de rotació X→Y→Z al applyTransform de wireframe3d.
+        // Si forward és quasi vertical (sin(pitch) ≈ 0), retorna yaw=0 (qualsevol).
+        auto computePitchYawForLookAt(const Vec3& forward_dir) -> Vec2 {
+            const float DY = std::clamp(forward_dir.y, -1.0F, 1.0F);
+            const float PITCH = -std::acos(-DY);  // ∈ [-π, 0]
+            const float SIN_PITCH = std::sin(PITCH);
+            if (std::abs(SIN_PITCH) < 1.0E-5F) {
+                return Vec2{.x = PITCH, .y = 0.0F};
+            }
+            const float SY = -forward_dir.x / SIN_PITCH;
+            const float CY = -forward_dir.z / SIN_PITCH;
+            return Vec2{.x = PITCH, .y = std::atan2(SY, CY)};
+        }
+
+        auto safeNormalize(const Vec3& v, const Vec3& fallback) -> Vec3 {
+            return v.lengthSquared() > 0.0F ? v.normalized() : fallback;
+        }
+
+        auto entryForward(const TitleShip3D& ship) -> Vec3 {
+            return safeNormalize(ship.target_position - ship.initial_position,
+                Vec3{.x = 0.0F, .y = 0.0F, .z = 1.0F});
+        }
+
+        auto floatingForward(const Vec3& target) -> Vec3 {
+            return safeNormalize(VANISHING_POINT - target,
+                Vec3{.x = 0.0F, .y = 0.0F, .z = 1.0F});
+        }
+
+        auto exitForward(const Vec3& current) -> Vec3 {
+            return safeNormalize(VANISHING_POINT - current,
+                Vec3{.x = 0.0F, .y = 0.0F, .z = 1.0F});
+        }
+
         // Mida visual i animació.
         constexpr float SHIP_FLOAT_SCALE = 1.0F;
         constexpr float SHIP_ENTRY_SCALE = 1.0F;  // Mida mundial idèntica; la perspectiva fa la resta
@@ -107,9 +138,10 @@ namespace Title {
             if (!ship.visible) {
                 continue;
             }
+            const Vec2 EULER = computePitchYawForLookAt(ship.forward_dir);
             const Graphics::Transform3D TRANSFORM{
                 .position = ship.current_position,
-                .rotation_euler = Vec3{.x = SHIP_PITCH_RAD, .y = 0.0F, .z = 0.0F},
+                .rotation_euler = Vec3{.x = EULER.x, .y = EULER.y, .z = 0.0F},
                 .scale = ship.current_scale,
             };
             Graphics::drawWireframe(renderer_, *camera_, ship.mesh, TRANSFORM, 1.0F);
@@ -122,6 +154,7 @@ namespace Title {
             ship.state_time = 0.0F;
             ship.current_position = ship.initial_position;
             ship.current_scale = ship.initial_scale;
+            ship.forward_dir = entryForward(ship);
         }
     }
 
@@ -130,6 +163,7 @@ namespace Title {
             ship.state = ShipState3D::EXITING;
             ship.state_time = 0.0F;
             ship.initial_position = ship.current_position;
+            ship.forward_dir = exitForward(ship.current_position);
         }
     }
 
@@ -139,6 +173,7 @@ namespace Title {
                 ship.state = ShipState3D::EXITING;
                 ship.state_time = 0.0F;
                 ship.initial_position = ship.current_position;
+                ship.forward_dir = exitForward(ship.current_position);
                 break;
             }
         }
@@ -151,6 +186,7 @@ namespace Title {
             ship.oscillation_phase = 0.0F;
             ship.current_position = ship.target_position;
             ship.current_scale = ship.target_scale;
+            ship.forward_dir = floatingForward(ship.target_position);
         }
     }
 
@@ -207,6 +243,7 @@ namespace Title {
             ship.state_time = 0.0F;
             // No resetegem oscillation_phase: així updateFloating continua
             // l'oscil·lació iniciada durant ENTERING sense salt.
+            ship.forward_dir = floatingForward(ship.target_position);
         }
     }
 
@@ -264,6 +301,7 @@ namespace Title {
         ship.amplitude_y = FLOAT_AMPLITUDE_Y;
         ship.frequency_x = FLOAT_FREQUENCY_X_BASE * P1_FREQUENCY_MULTIPLIER;
         ship.frequency_y = FLOAT_FREQUENCY_Y_BASE * P1_FREQUENCY_MULTIPLIER;
+        ship.forward_dir = entryForward(ship);
         ship.visible = true;
     }
 
@@ -289,6 +327,7 @@ namespace Title {
         ship.amplitude_y = FLOAT_AMPLITUDE_Y;
         ship.frequency_x = FLOAT_FREQUENCY_X_BASE * P2_FREQUENCY_MULTIPLIER;
         ship.frequency_y = FLOAT_FREQUENCY_Y_BASE * P2_FREQUENCY_MULTIPLIER;
+        ship.forward_dir = entryForward(ship);
         ship.visible = true;
     }