set_fov: Add support for time-based transitions (#9705)

doc/lua_api.txt

@@ -5998,15 +5998,18 @@ object you are working with still exists.
         * max: bubbles bar is not shown
         * See [Object properties] for more information
     * Is limited to range 0 ... 65535 (2^16 - 1)
-* `set_fov(fov, is_multiplier)`: Sets player's FOV
+* `set_fov(fov, is_multiplier, transition_time)`: Sets player's FOV
     * `fov`: FOV value.
     * `is_multiplier`: Set to `true` if the FOV value is a multiplier.
       Defaults to `false`.
-    * Set to 0 to clear FOV override.
-* `get_fov()`:
-    * Returns player's FOV override in degrees, and a boolean depending on whether
-      the value is a multiplier.
-    * Returns 0 as first value if player's FOV hasn't been overridden.
+    * `transition_time`: If defined, enables smooth FOV transition.
+      Interpreted as the time (in seconds) to reach target FOV.
+      If set to 0, FOV change is instantaneous. Defaults to 0.
+    * Set `fov` to 0 to clear FOV override.
+* `get_fov()`: Returns the following:
+    * Server-sent FOV value. Returns 0 if an FOV override doesn't exist.
+    * Boolean indicating whether the FOV value is a multiplier.
+    * Time (in seconds) taken for the FOV transition. Set by `set_fov`.
 * `set_attribute(attribute, value)`:  DEPRECATED, use get_meta() instead
     * Sets an extra attribute with value on player.
     * `value` must be a string, or a number which will be converted to a

src/client/camera.cpp

@@ -86,6 +86,51 @@ Camera::~Camera()
 	m_wieldmgr->drop();
 }
 
+void Camera::notifyFovChange()
+{
+	LocalPlayer *player = m_client->getEnv().getLocalPlayer();
+	assert(player);
+
+	PlayerFovSpec spec = player->getFov();
+
+	/*
+	 * Update m_old_fov_degrees first - it serves as the starting point of the
+	 * upcoming transition.
+	 *
+	 * If an FOV transition is already active, mark current FOV as the start of
+	 * the new transition. If not, set it to the previous transition's target FOV.
+	 */
+	if (m_fov_transition_active)
+		m_old_fov_degrees = m_curr_fov_degrees;
+	else
+		m_old_fov_degrees = m_server_sent_fov ? m_target_fov_degrees : m_cache_fov;
+
+	/*
+	 * Update m_server_sent_fov next - it corresponds to the target FOV of the
+	 * upcoming transition.
+	 *
+	 * Set it to m_cache_fov, if server-sent FOV is 0. Otherwise check if
+	 * server-sent FOV is a multiplier, and multiply it with m_cache_fov instead
+	 * of overriding.
+	 */
+	if (spec.fov == 0.0f) {
+		m_server_sent_fov = false;
+		m_target_fov_degrees = m_cache_fov;
+	} else {
+		m_server_sent_fov = true;
+		m_target_fov_degrees = spec.is_multiplier ? m_cache_fov * spec.fov : spec.fov;
+	}
+
+	if (spec.transition_time > 0.0f)
+		m_fov_transition_active = true;
+
+	// If FOV smooth transition is active, initialize required variables
+	if (m_fov_transition_active) {
+		m_transition_time = spec.transition_time;
+		m_fov_diff = m_target_fov_degrees - m_old_fov_degrees;
+	}
+}
+
 bool Camera::successfullyCreated(std::string &error_message)
 {
 	if (!m_playernode) {
@@ -462,33 +507,38 @@ void Camera::update(LocalPlayer* player, f32 frametime, f32 busytime, f32 tool_r
 		m_camera_position = my_cp;
 
 	/*
-	 * Apply server-sent FOV. If server doesn't enforce FOV,
-	 * check for zoom and set to zoom FOV.
-	 * Otherwise, default to m_cache_fov
+	 * Apply server-sent FOV, instantaneous or smooth transition.
+	 * If not, check for zoom and set to zoom FOV.
+	 * Otherwise, default to m_cache_fov.
 	 */
+	if (m_fov_transition_active) {
+		// Smooth FOV transition
+		// Dynamically calculate FOV delta based on frametimes
+		f32 delta = (frametime / m_transition_time) * m_fov_diff;
+		m_curr_fov_degrees += delta;
 
-	f32 fov_degrees;
-	PlayerFovSpec fov_spec = player->getFov();
-	if (fov_spec.fov > 0.0f) {
-		// If server-sent FOV is a multiplier, multiply
-		// it with m_cache_fov instead of overriding
-		if (fov_spec.is_multiplier)
-			fov_degrees = m_cache_fov * fov_spec.fov;
-		else
-			fov_degrees = fov_spec.fov;
+		// Mark transition as complete if target FOV has been reached
+		if ((m_fov_diff > 0.0f && m_curr_fov_degrees >= m_target_fov_degrees) ||
+				(m_fov_diff < 0.0f && m_curr_fov_degrees <= m_target_fov_degrees)) {
+			m_fov_transition_active = false;
+			m_curr_fov_degrees = m_target_fov_degrees;
+		}
+	} else if (m_server_sent_fov) {
+		// Instantaneous FOV change
+		m_curr_fov_degrees = m_target_fov_degrees;
 	} else if (player->getPlayerControl().zoom && player->getZoomFOV() > 0.001f) {
 		// Player requests zoom, apply zoom FOV
-		fov_degrees = player->getZoomFOV();
+		m_curr_fov_degrees = player->getZoomFOV();
 	} else {
 		// Set to client's selected FOV
-		fov_degrees = m_cache_fov;
+		m_curr_fov_degrees = m_cache_fov;
 	}
-	fov_degrees = rangelim(fov_degrees, 1.0f, 160.0f);
+	m_curr_fov_degrees = rangelim(m_curr_fov_degrees, 1.0f, 160.0f);
 
 	// FOV and aspect ratio
 	const v2u32 &window_size = RenderingEngine::get_instance()->getWindowSize();
 	m_aspect = (f32) window_size.X / (f32) window_size.Y;
-	m_fov_y = fov_degrees * M_PI / 180.0;
+	m_fov_y = m_curr_fov_degrees * M_PI / 180.0;
 	// Increase vertical FOV on lower aspect ratios (<16:10)
 	m_fov_y *= MYMAX(1.0, MYMIN(1.4, sqrt(16./10. / m_aspect)));
 	m_fov_x = 2 * atan(m_aspect * tan(0.5 * m_fov_y));

src/client/camera.h

@@ -112,6 +112,9 @@ public:
 		return MYMAX(m_fov_x, m_fov_y);
 	}
 
+	// Notify about new server-sent FOV and initialize smooth FOV transition
+	void notifyFovChange();
+
 	// Checks if the constructor was able to create the scene nodes
 	bool successfullyCreated(std::string &error_message);
 
@@ -186,6 +189,9 @@ private:
 
 	Client *m_client;
 
+	// Default Client FOV (as defined by the "fov" setting)
+	f32 m_cache_fov;
+
 	// Absolute camera position
 	v3f m_camera_position;
 	// Absolute camera direction
@@ -193,6 +199,14 @@ private:
 	// Camera offset
 	v3s16 m_camera_offset;
 
+	// Server-sent FOV variables
+	bool m_server_sent_fov = false;
+	f32 m_curr_fov_degrees, m_old_fov_degrees, m_target_fov_degrees;
+
+	// FOV transition variables
+	bool m_fov_transition_active = false;
+	f32 m_fov_diff, m_transition_time;
+
 	v2f m_wieldmesh_offset = v2f(55.0f, -35.0f);
 	v2f m_arm_dir;
 	v2f m_cam_vel;
@@ -230,7 +244,6 @@ private:
 
 	f32 m_cache_fall_bobbing_amount;
 	f32 m_cache_view_bobbing_amount;
-	f32 m_cache_fov;
 	bool m_arm_inertia;
 
 	std::list<Nametag *> m_nametags;

src/network/clientpackethandler.cpp

@@ -20,6 +20,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "client/client.h"
 
 #include "util/base64.h"
+#include "client/camera.h"
 #include "chatmessage.h"
 #include "client/clientmedia.h"
 #include "log.h"
@@ -530,11 +531,21 @@ void Client::handleCommand_Movement(NetworkPacket* pkt)
 void Client::handleCommand_Fov(NetworkPacket *pkt)
 {
 	f32 fov;
-	bool is_multiplier;
+	bool is_multiplier = false;
+	f32 transition_time = 0.0f;
+
 	*pkt >> fov >> is_multiplier;
 
+	// Wrap transition_time extraction within a
+	// try-catch to preserve backwards compat
+	try {
+		*pkt >> transition_time;
+	} catch (PacketError &e) {};
+
 	LocalPlayer *player = m_env.getLocalPlayer();
-	player->setFov({ fov, is_multiplier });
+	assert(player);
+	player->setFov({ fov, is_multiplier, transition_time });
+	m_camera->notifyFovChange();
 }
 
 void Client::handleCommand_HP(NetworkPacket *pkt)

src/network/networkprotocol.h

@@ -384,8 +384,9 @@ enum ToClientCommand
 	/*
 		Sends an FOV override/multiplier to client.
 
-		float fov
+		f32 fov
 		bool is_multiplier
+		f32 transition_time
 	*/
 
 	TOCLIENT_DEATHSCREEN = 0x37,

src/player.h

@@ -35,7 +35,13 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 struct PlayerFovSpec
 {
 	f32 fov;
+
+	// Whether to multiply the client's FOV or to override it
 	bool is_multiplier;
+
+	// The time to be take to trasition to the new FOV value.
+	// Transition is instantaneous if omitted. Omitted by default.
+	f32 transition_time;
 };
 
 struct PlayerControl
@@ -186,12 +192,12 @@ public:
 
 	void setFov(const PlayerFovSpec &spec)
 	{
-		m_fov_spec = spec;
+		m_fov_override_spec = spec;
 	}
 
 	const PlayerFovSpec &getFov() const
 	{
-		return m_fov_spec;
+		return m_fov_override_spec;
 	}
 
 	u32 keyPressed = 0;
@@ -208,7 +214,7 @@ protected:
 	char m_name[PLAYERNAME_SIZE];
 	v3f m_speed;
 	u16 m_wield_index = 0;
-	PlayerFovSpec m_fov_spec = { 0.0f, false };
+	PlayerFovSpec m_fov_override_spec = { 0.0f, false, 0.0f };
 
 	std::vector<HudElement *> hud;
 private:

src/script/lua_api/l_object.cpp

@@ -1249,7 +1249,7 @@ int ObjectRef::l_set_look_yaw(lua_State *L)
 	return 1;
 }
 
-// set_fov(self, degrees[, is_multiplier])
+// set_fov(self, degrees[, is_multiplier, transition_time])
 int ObjectRef::l_set_fov(lua_State *L)
 {
 	NO_MAP_LOCK_REQUIRED;
@@ -1258,7 +1258,11 @@ int ObjectRef::l_set_fov(lua_State *L)
 	if (!player)
 		return 0;
 
-	player->setFov({ static_cast<f32>(luaL_checknumber(L, 2)), readParam<bool>(L, 3) });
+	player->setFov({
+		static_cast<f32>(luaL_checknumber(L, 2)),
+		readParam<bool>(L, 3, false),
+		lua_isnumber(L, 4) ? static_cast<f32>(luaL_checknumber(L, 4)) : 0.0f
+	});
 	getServer(L)->SendPlayerFov(player->getPeerId());
 
 	return 0;
@@ -1276,8 +1280,9 @@ int ObjectRef::l_get_fov(lua_State *L)
 	PlayerFovSpec fov_spec = player->getFov();
 	lua_pushnumber(L, fov_spec.fov);
 	lua_pushboolean(L, fov_spec.is_multiplier);
+	lua_pushnumber(L, fov_spec.transition_time);
 
-	return 2;
+	return 3;
 }
 
 // set_breath(self, breath)

src/server.cpp

@@ -1892,10 +1892,10 @@ void Server::SendMovePlayer(session_t peer_id)
 
 void Server::SendPlayerFov(session_t peer_id)
 {
-	NetworkPacket pkt(TOCLIENT_FOV, 4 + 1, peer_id);
+	NetworkPacket pkt(TOCLIENT_FOV, 4 + 1 + 4, peer_id);
 
 	PlayerFovSpec fov_spec = m_env->getPlayer(peer_id)->getFov();
-	pkt << fov_spec.fov << fov_spec.is_multiplier;
+	pkt << fov_spec.fov << fov_spec.is_multiplier << fov_spec.transition_time;
 
 	Send(&pkt);
 }