Add Arm Inertia (#6050)

3 files changed, 90 insertions, 3 deletions

diff --git a/src/camera.cpp b/src/camera.cpp
index d5e32bf5a..f75d6018d 100644
--- a/src/camera.cpp
+++ b/src/camera.cpp
@@ -75,6 +75,7 @@ Camera::Camera(scene::ISceneManager* smgr, MapDrawControl& draw_control,
 	m_cache_view_bobbing_amount = g_settings->getFloat("view_bobbing_amount");
 	m_cache_fov                 = g_settings->getFloat("fov");
 	m_cache_zoom_fov            = g_settings->getFloat("zoom_fov");
+	m_arm_inertia		    = g_settings->getBool("arm_inertia");
 	m_nametags.clear();
 }
 
@@ -193,6 +194,82 @@ void Camera::step(f32 dtime)
 	}
 }
 
+void Camera::add_arm_inertia(f32 player_yaw, f32 frametime)
+{
+	m_cam_vel.X = std::fabs((m_last_cam_pos.X - player_yaw) / m_timer.X) * 0.01f;
+	m_cam_vel.Y = std::fabs((m_last_cam_pos.Y - m_camera_direction.Y) / m_timer.Y);
+
+	if (m_cam_vel.X > 1.0f || m_cam_vel.Y > 1.0f) {
+		/*
+		   the arm moves when the camera moves fast enough.
+		*/
+
+		if (m_cam_vel.X > 1.0f) {
+			m_timer.X = 0.0f;
+			m_timer.X += frametime;
+
+			if (m_cam_vel.X > m_cam_vel_old.X)
+				m_cam_vel_old.X = m_cam_vel.X;
+
+			if (m_last_cam_pos.X > player_yaw)
+				// right
+				m_wieldmesh_offset.X -= (0.1f + frametime) * m_cam_vel.X;
+			else
+				// left
+				m_wieldmesh_offset.X += (0.1f + frametime) * m_cam_vel.X;
+
+			if (m_last_cam_pos.X != player_yaw)
+				m_last_cam_pos.X = player_yaw;
+
+			m_wieldmesh_offset.X = rangelim(m_wieldmesh_offset.X, 48.0f, 62.0f);
+		}
+
+		if (m_cam_vel.Y > 1.0f) {
+			m_timer.Y = 0.0f;
+			m_timer.Y += frametime;
+
+			if (m_cam_vel.Y > m_cam_vel_old.Y)
+				m_cam_vel_old.Y = m_cam_vel.Y;
+
+			if (m_last_cam_pos.Y > m_camera_direction.Y)
+				// down
+				m_wieldmesh_offset.Y += (0.1f + frametime) * m_cam_vel.Y;
+			else
+				// up
+				m_wieldmesh_offset.Y -= (0.1f + frametime) * m_cam_vel.Y;
+
+			if (m_last_cam_pos.Y != m_camera_direction.Y)
+				m_last_cam_pos.Y = m_camera_direction.Y;
+
+			m_wieldmesh_offset.Y = rangelim(m_wieldmesh_offset.Y, -45.0f, -30.0f);
+		}
+	} else {
+		/*
+		   the arm now gets back to its default position when the camera stops.
+		*/
+
+		if (floor(m_wieldmesh_offset.X) == 55.0f) {
+			m_cam_vel_old.X = 0.0f;
+			m_wieldmesh_offset.X = 55.0f;
+		}
+
+		if (m_wieldmesh_offset.X > 55.0f)
+			m_wieldmesh_offset.X -= (0.05f + frametime) * m_cam_vel_old.X;
+		if (m_wieldmesh_offset.X < 55.0f)
+			m_wieldmesh_offset.X += (0.05f + frametime) * m_cam_vel_old.X;
+
+		if (floor(m_wieldmesh_offset.Y) == -35.0f) {
+			m_cam_vel_old.Y = 0.0f;
+			m_wieldmesh_offset.Y = -35.0f;
+		}
+
+		if (m_wieldmesh_offset.Y > -35.0f)
+			m_wieldmesh_offset.Y -= (0.05f + frametime) * m_cam_vel_old.Y;
+		if (m_wieldmesh_offset.Y < -35.0f)
+			m_wieldmesh_offset.Y += (0.05f + frametime) * m_cam_vel_old.Y;
+	}
+}
+
 void Camera::update(LocalPlayer* player, f32 frametime, f32 busytime,
 		f32 tool_reload_ratio, ClientEnvironment &c_env)
 {
@@ -380,12 +457,12 @@ void Camera::update(LocalPlayer* player, f32 frametime, f32 busytime,
 	m_cameranode->setAspectRatio(m_aspect);
 	m_cameranode->setFOV(m_fov_y);
 
-	float wieldmesh_offset_Y = -35 + player->getPitch() * 0.05;
-	wieldmesh_offset_Y = rangelim(wieldmesh_offset_Y, -52, -32);
+	if (m_arm_inertia)
+		add_arm_inertia(player->getYaw(), frametime);
 
 	// Position the wielded item
 	//v3f wield_position = v3f(45, -35, 65);
-	v3f wield_position = v3f(55, wieldmesh_offset_Y, 65);
+	v3f wield_position = v3f(m_wieldmesh_offset.X, m_wieldmesh_offset.Y, 65);
 	//v3f wield_rotation = v3f(-100, 120, -100);
 	v3f wield_rotation = v3f(-100, 120, -100);
 	wield_position.Y += fabs(m_wield_change_timer)*320 - 40;
diff --git a/src/camera.h b/src/camera.h
index 8d213ede7..9ed4b7277 100644
--- a/src/camera.h
+++ b/src/camera.h
@@ -166,6 +166,8 @@ public:
 
 	void drawNametags();
 
+	inline void add_arm_inertia(f32 player_yaw, f32 frametime);
+
 private:
 	// Nodes
 	scene::ISceneNode *m_playernode = nullptr;
@@ -188,6 +190,12 @@ private:
 	// Camera offset
 	v3s16 m_camera_offset;
 
+	v2f m_wieldmesh_offset = v2f(55.0f, -35.0f);
+	v2f m_timer;
+	v2f m_cam_vel;
+	v2f m_cam_vel_old;
+	v2f m_last_cam_pos;
+
 	// Field of view and aspect ratio stuff
 	f32 m_aspect = 1.0f;
 	f32 m_fov_x = 1.0f;
@@ -221,6 +229,7 @@ private:
 	f32 m_cache_view_bobbing_amount;
 	f32 m_cache_fov;
 	f32 m_cache_zoom_fov;
+	bool m_arm_inertia;
 
 	std::list<Nametag *> m_nametags;
 };
diff --git a/src/defaultsettings.cpp b/src/defaultsettings.cpp
index c10d2cb02..42e369f60 100644
--- a/src/defaultsettings.cpp
+++ b/src/defaultsettings.cpp
@@ -171,6 +171,7 @@ void set_default_settings(Settings *settings)
 	settings->setDefault("ambient_occlusion_gamma", "2.2");
 	settings->setDefault("enable_shaders", "true");
 	settings->setDefault("enable_particles", "true");
+	settings->setDefault("arm_inertia", "true");
 
 	settings->setDefault("enable_minimap", "true");
 	settings->setDefault("minimap_shape_round", "true");