Merge pull request #51 from orange-cpp/feature/projectile_pred_custom

Refactors projectile prediction engine

include/omath/projectile_prediction/proj_pred_engine.hpp

@@ -8,12 +8,12 @@
 
 namespace omath::projectile_prediction
 {
-    class ProjPredEngine
+    class ProjPredEngineInterface
     {
     public:
         [[nodiscard]]
         virtual std::optional<Vector3<float>> maybe_calculate_aim_point(const Projectile& projectile,
                                                                         const Target& target) const = 0;
-        virtual ~ProjPredEngine() = default;
+        virtual ~ProjPredEngineInterface() = default;
     };
 } // namespace omath::projectile_prediction

include/omath/projectile_prediction/proj_pred_engine_avx2.hpp

@@ -6,7 +6,7 @@
 
 namespace omath::projectile_prediction
 {
-    class ProjPredEngineAvx2 final : public ProjPredEngine
+    class ProjPredEngineAvx2 final : public ProjPredEngineInterface
     {
     public:
         [[nodiscard]] std::optional<Vector3<float>>

include/omath/projectile_prediction/proj_pred_engine_legacy.hpp

@@ -12,7 +12,8 @@
 
 namespace omath::projectile_prediction
 {
-    class ProjPredEngineLegacy final : public ProjPredEngine
+    // ReSharper disable once CppClassCanBeFinal
+    class ProjPredEngineLegacy : public ProjPredEngineInterface
     {
     public:
         explicit ProjPredEngineLegacy(float gravity_constant, float simulation_time_step, float maximum_simulation_time,
@@ -28,6 +29,18 @@ namespace omath::projectile_prediction
         const float m_maximum_simulation_time;
         const float m_distance_tolerance;
 
+        // Realization of this formula:
+        // https://stackoverflow.com/questions/54917375/how-to-calculate-the-angle-to-shoot-a-bullet-in-order-to-hit-a-moving-target
+        /*
+        \[
+        \theta \;=\; \arctan\!\Biggl(
+        \frac{%
+        v^{2}\;\pm\;\sqrt{\,v^{4}-g\!\left(gx^{2}+2yv^{2}\right)\,}
+        }{%
+        gx
+       }\Biggr)
+       \]
+        */
         [[nodiscard]]
         std::optional<float>
         maybe_calculate_projectile_launch_pitch_angle(const Projectile& projectile,
@@ -36,5 +49,25 @@ namespace omath::projectile_prediction
         [[nodiscard]]
         bool is_projectile_reached_target(const Vector3<float>& target_position, const Projectile& projectile,
                                           float pitch, float time) const noexcept;
+
+    protected:
+        // NOTE: Override this if you need to use engine with different coordinate system
+        // Like where Z is not height coordinate
+        // ===============================================================================================
+        [[nodiscard]]
+        virtual float calc_vector_2d_distance(const Vector3<float>& delta) const;
+
+        [[nodiscard]]
+        virtual float get_vector_height_coordinate(const Vector3<float>& vec) const;
+
+        [[nodiscard]]
+        virtual Vector3<float> calc_viewpoint_from_angles(const Projectile& projectile,
+                                                          Vector3<float> predicted_target_position,
+                                                          std::optional<float> projectile_pitch) const;
+
+        [[nodiscard]]
+        virtual Vector3<float> predict_projectile_position(const Projectile& projectile, float pitch, float yaw,
+                                                           float time, float gravity) const;
+        // ===============================================================================================
     };
 } // namespace omath::projectile_prediction

include/omath/projectile_prediction/projectile.hpp

@@ -10,9 +10,6 @@ namespace omath::projectile_prediction
     class Projectile final
     {
     public:
-        [[nodiscard]]
-        Vector3<float> predict_position(float pitch, float yaw, float time, float gravity) const noexcept;
-
         Vector3<float> m_origin;
         float m_launch_speed{};
         float m_gravity_scale{};

source/projectile_prediction/proj_pred_engine_legacy.cpp

@@ -27,10 +27,7 @@ namespace omath::projectile_prediction
             if (!is_projectile_reached_target(predicted_target_position, projectile, projectile_pitch.value(), time))
                 continue;
 
-            const auto delta2d = (predicted_target_position - projectile.m_origin).length_2d();
-            const auto height = delta2d * std::tan(angles::degrees_to_radians(projectile_pitch.value()));
-
-            return Vector3(predicted_target_position.x, predicted_target_position.y, projectile.m_origin.z + height);
+            return calc_viewpoint_from_angles(projectile, predicted_target_position, projectile_pitch);
         }
         return std::nullopt;
     }
@@ -41,12 +38,14 @@ namespace omath::projectile_prediction
         const auto bullet_gravity = m_gravity_constant * projectile.m_gravity_scale;
         const auto delta = target_position - projectile.m_origin;
 
-        const auto distance2d = delta.length_2d();
+        const auto distance2d = calc_vector_2d_distance(delta);
         const auto distance2d_sqr = distance2d * distance2d;
         const auto launch_speed_sqr = projectile.m_launch_speed * projectile.m_launch_speed;
 
         float root = launch_speed_sqr * launch_speed_sqr
-                     - bullet_gravity * (bullet_gravity * distance2d_sqr + 2.0f * delta.z * launch_speed_sqr);
+                     - bullet_gravity
+                               * (bullet_gravity * distance2d_sqr
+                                  + 2.0f * get_vector_height_coordinate(delta) * launch_speed_sqr);
 
         if (root < 0.0f) [[unlikely]]
             return std::nullopt;
@@ -62,8 +61,40 @@ namespace omath::projectile_prediction
                                                             const float time) const noexcept
     {
         const auto yaw = projectile.m_origin.view_angle_to(target_position).y;
-        const auto projectile_position = projectile.predict_position(pitch, yaw, time, m_gravity_constant);
+        const auto projectile_position = predict_projectile_position(projectile, pitch, yaw, time, m_gravity_constant);
 
         return projectile_position.distance_to(target_position) <= m_distance_tolerance;
     }
+
+    float ProjPredEngineLegacy::calc_vector_2d_distance(const Vector3<float>& delta) const
+    {
+        return std::sqrt(delta.x * delta.x + delta.y * delta.y);
+    }
+
+    float ProjPredEngineLegacy::get_vector_height_coordinate(const Vector3<float>& vec) const
+    {
+        return vec.z;
+    }
+    Vector3<float> ProjPredEngineLegacy::calc_viewpoint_from_angles(const Projectile& projectile,
+                                                                    const Vector3<float> predicted_target_position,
+                                                                    const std::optional<float> projectile_pitch) const
+    {
+        const auto delta2d = calc_vector_2d_distance(predicted_target_position - projectile.m_origin);
+        const auto height = delta2d * std::tan(angles::degrees_to_radians(projectile_pitch.value()));
+
+        return {predicted_target_position.x, predicted_target_position.y, projectile.m_origin.z + height};
+    }
+    Vector3<float> ProjPredEngineLegacy::predict_projectile_position(const Projectile& projectile, const float pitch,
+                                                                     const float yaw, const float time,
+                                                                     const float gravity) const
+    {
+        auto current_pos = projectile.m_origin
+                           + source_engine::forward_vector({source_engine::PitchAngle::from_degrees(-pitch),
+                                                            source_engine::YawAngle::from_degrees(yaw),
+                                                            source_engine::RollAngle::from_degrees(0)})
+                                     * projectile.m_launch_speed * time;
+        current_pos.z -= (gravity * projectile.m_gravity_scale) * (time * time) * 0.5f;
+
+        return current_pos;
+    }
 } // namespace omath::projectile_prediction

source/projectile_prediction/projectile.cpp

@@ -7,16 +7,4 @@
 
 namespace omath::projectile_prediction
 {
-    Vector3<float> Projectile::predict_position(const float pitch, const float yaw, const float time,
-                                                const float gravity) const noexcept
-    {
-        auto current_pos = m_origin
-                           + source_engine::forward_vector({source_engine::PitchAngle::from_degrees(-pitch),
-                                                            source_engine::YawAngle::from_degrees(yaw),
-                                                            source_engine::RollAngle::from_degrees(0)})
-                                     * m_launch_speed * time;
-        current_pos.z -= (gravity * m_gravity_scale) * (time * time) * 0.5f;
-
-        return current_pos;
-    }
 } // namespace omath::projectile_prediction