SFML UDP lag on localhost - c++

Question

I am currently using SFML to create a game which will allow a client to connect and watch the player gameplay. This is currently being done on localhost, 127.0.0.1 on same port since its UDP.
I am launching two executables - one will be client and the other will be the main player[udpserver].
I am noticing that on the client, there is jittering when spaceship moves, and also bullet is drawn two or three times in instantiating position before going upward. (when bullet spawns, it is rendered to go upward, code executes for both client and server). This is what I have -
void createUdpServer(unsigned short port) { // send data to client
// Create a socket to receive a message from anyone
sf::UdpSocket socket;
sf::IpAddress local = sf::IpAddress::getLocalAddress(); // Currently 127.0.0.1 localhost
sf::IpAddress receiver = sf::IpAddress::getLocalAddress();
socket.setBlocking(false);
// I was figuring out and arranging according to example.. set socket non blocking
// Listen to messages on the specified port
if (socket.bind(port) != sf::Socket::Done && !portBound) // You bind once
return; // error
else {
portBound = true;
}
std::cout << "Server is listening to port " << port << ", waiting for a connection... " << std::endl;
// Wait for a message
char in[128];
std::size_t received;
sf::IpAddress sender;
//unsigned short senderPort; we will be receiving and sending data on sa,e port
sf::SocketSelector selector;
selector.add(socket);
if (selector.wait(sf::milliseconds(10.f))) { // times out after 10ms
if (selector.isReady(socket)) {
if (socket.receive(in, sizeof(in), received, sender, port) != sf::Socket::Done) // blocking
return;
std::cout << "Message received from client " << sender << ": \"" << in << "\"" << std::endl;
}
}
// Sends connection established to client
/*
const char out[] = "Connection with server established!";
if (socket.send(out, sizeof(out), sender, port) != sf::Socket::Done)
return;
*/
// acknowledgement of packets
float playerXPosition = player->getPosition().x;
float playerYPosition = player->getPosition().y;
sf::Packet playerData;
sf::Packet bulletData;
playerData << playerXPosition << playerYPosition << bulletPtr->isAlive() << bulletPtr->getLocation().x << bulletPtr->getLocation().y;
//bulletData << bulletPtr->isAlive() << bulletPtr->getLocation().x << bulletPtr->getLocation().y;
socket.send(playerData, sender, port);
//socket.send(bulletData, sender, port);
//const char out[] = "";
//if (socket.send(out, sizeof(out), sender, port) != sf::Socket::Done)
// return;
}
void runUdpClient(unsigned short port) { // receive data from server
// Ask for the server address
server = "127.0.0.1";
/*
if (server == sf::IpAddress::None)
do
{
std::cout << "Type the address or name of the server to connect to: ";
std::cin >> server;
} while (server != sf::IpAddress::None);
*/
// Create a socket for communicating with the server
sf::UdpSocket socket;
sf::IpAddress recipient = sf::IpAddress::getLocalAddress();
char data[100] = "Connection with client established!";
if (socket.send(data, 100, server, port) != sf::Socket::Done && !sendInitialToServer) // if send once dont't send again
{
// added up top send this only once
// error...
}
else{
sendInitialToServer = true;
}
// Think about putting this globally
sf::SocketSelector selector;
selector.add(socket);
if (selector.wait(sf::milliseconds(10.f))) { // not enough time for server to be created with 0.1f
// received something
if (selector.isReady(socket)) {
// Wait for a message
char in[128];
std::size_t received; // am I using this?
sf::IpAddress sender;
sf::Packet playerData;
sf::Packet bulletData;
float playerXPosition;
float playerYPosition;
float clientXPosition;
float clientYPosition;
float clientBulletX;
float clientBulletY;
bool bulletShot;
socket.receive(playerData, sender, port);
//socket.receive(bulletData, sender, port);
if (playerData >> playerXPosition >> playerYPosition >> bulletShot >> clientBulletX >> clientBulletY) { // if you are able to read
clientXPosition = playerXPosition;
clientYPosition = playerYPosition;
player->setPosition(clientXPosition, clientYPosition);
if (bulletShot) {
// - might not need this
bulletPtr->spawn(true); // once bullet spawned, should be taken care of both sides
if (bulletPtr->isAlive())
bulletPtr->setLocation(clientXPosition - 13.f, clientYPosition - 24.f);
//else
// clientbulletx and clientbullety
//bulletPtr->draw(window); // client window handled from both client and server what to do if bullet is alive
}
}
/*
if (bulletData >> bulletShot >> clientBulletX >> clientBulletY) {
if (bulletShot) {
bulletPtr->spawn(true); // once bullet spawned, should be taken care of both sides
bulletPtr->setLocation(player->getPosition().x - 13.f, player->getPosition().y - 24.f);
//bulletPtr->draw(window); // client window handled from both client and server what to do if bullet is alive
}
}*/
else {
// Handle error / packet loss // else simulate?
std::cout << "Error - failed to read from player data packet!" << std::endl; // this is normal when packet is lost
// I think I am getting several packet drops as I am receiving and sending from the same PC same port, localhost
}
//unsigned short senderPort;
//if (socket.receive(in, sizeof(in), received, sender, port) != sf::Socket::Done)
// return;
//std::cout << "Message received from server " << sender << ": \"" << in << "\"" << std::endl;
}
// this shouldn't be here, receive stuff should go on client, server just sends
}
else {
// timeout reached, nothing was received
}
// prediction
// bullet
}
Let me know if I can provide additional information. This is the order of execution from main -
while (window.isOpen())
{
if (userChoice == NULL){
do {
std::cout << "User Choice - " << userChoice << std::endl;
std::cout << "Server or client? (s/c)" << std::endl;
std::cin >> userChoice;
} while (userChoice != 's' && userChoice != 'c');
// The game clock will keep on restarting until the user makes a decision
clock.restart(); // This solved issue to start movements and updates at same time once user chooses an option
}
if (userChoice == 's' || userChoice == 'c') { // start of main if // else start the whole program
// game time over here once game starts // frame independent
// Binding of ports for both client or server
/*
// bind the socket to a port
if (socket.bind(54000) != sf::Socket::Done)
{
// Using UDP starts listening on this port
// whatever happens, bind for both -> will work with two executables running on same network with two different local IPs
}
*/
// Puts the time counter back to zero and also returns the time elapsed since the clock was started
sf::Time deltaTime = clock.restart();
timeSinceLastUpdate += deltaTime;
while (timeSinceLastUpdate > TimePerFrame) // fixed time steps // userchoice != NULL otherwise it will start immeadiately
{
timeSinceLastUpdate -= TimePerFrame; // solves problem with variable delta time, each frame is unique
processEvents(window);
//update(TimePerFrame);
// Start of if server
if (userChoice == 's'){
//if(!serverCreated){ // if problems of continous connection, this needs to place outside of bind
// create connection
createUdpServer(SERVER_PORT); // over here its happening every frame
//serverCreated = true; // is server actually created though?
//}
// Player 1 movement
sf::Vector2f movement(0.f, 0.f);
if (mIsMovingUp)
movement.y -= playerSpeed;
if (mIsMovingDown)
movement.y += playerSpeed;
if (mIsMovingLeft)
movement.x -= playerSpeed;
if (mIsMovingRight)
movement.x += playerSpeed;
// shooting logic
if (mIsShooting) {
if (!bullet.isAlive()) // && !gameOver
{
bullet.spawn(true);
bullet.setLocation(mPlayer.getPosition().x - 13.f, mPlayer.getPosition().y - 24.f); // mPlayer.getPosition().x + 24 (offset) if origin is not set to center
}
}
// ** These two parts need to be put in an if statement, if server, direct movement, if client, move needs to happen with data received
// from server (Server - main player streamer; Client - viewer)
// Possibly this will be the data that needs to be sent to server
mPlayer.move(movement * TimePerFrame.asSeconds()); // Time.deltaTime frame independent movement
// for each player eventually
screenBound(mPlayer);
// screenbound enemies or else check that they do not go off bounds and change direction
// **
} // end of if server
else {
// Handle control through incoming network data
// vector x = datacoming in
// Hypothetically mPlayer.move(data coming in);
// bullet spawn
// setlocation from data packet
runUdpClient(SERVER_PORT);
}
// Enemy Behaviour // Ideally move to separate method
sf::Vector2f enemyMovement(1.f, 0.f);
float yOffset = 30.f;
float xOffset = 60.f;
// Be careful with iterators as when deleting it will automatically jump to the next item in vector
for (std::vector<Enemy>::iterator i = enemyList->begin(); i != enemyList->end(); ++i) // CAUTION & solved everything again - lesson in C++, if we don't get address, we always create a copy and modify it, which is not what we want
{
//std::cout << "Direction before working move " << direction << std::endl;
i->getSprite().move(enemyMovement * direction); // Issue detected direction only changing sign if greater or less than screen bounds once
if (i->getSprite().getPosition().x + i->getSprite().getLocalBounds().width / 2 > game->getWindowWidth() ||
i->getSprite().getPosition().x - i->getSprite().getLocalBounds().width / 2 < game->getWindowWidth() - game->getWindowWidth()) { // this will be 0
direction = -(direction);
// Time stamp over here for network calculations
//std::cout << "Direction inside if statement " << direction << std::endl;
// another for loop move all down by yOffset
for (std::vector<Enemy>::iterator i = enemyList->begin(); i != enemyList->end(); ++i) {
i->getSprite().setPosition(i->getSprite().getPosition().x, i->getSprite().getPosition().y + yOffset);
//enemy.move(0.f, enemy.getPosition().y + yOffset);
}
//enemy.setPosition(enemy.getPosition().x, enemy.getPosition().y + yOffset); // y axis is inverted in SFML
//return 0; // move to separate method
}
// This takes care of everything on both sides
if ((i->getSprite().getPosition().y > game->getWindowHeight() - mPlayer.getLocalBounds().height)) {
//removeEnemy(enemy);
// ALIVE is false, then draw based on whether alien is alive or not
std::cout << "Everyone should be dead game over!" << std::endl;
return 0; // change state to paused
}
}
}
updateStatistics(deltaTime, mStatisticsText);
// ** Start of if server
if (userChoice == 's'){
for (std::vector<Enemy>::iterator i = enemyList->begin(); i != enemyList->end(); ++i) {
// Test player and alien collision
if (CollisionManager::collidesWith(mPlayer, *i) && i->isAlive()) { // *i it points to the enemy, and will give me an enemy
std::cout << "You're dead!" << std::endl;
mPlayerIsAlive = false;
return 0; //-> I'm dead gameOver = true;
}
// Test collision between bullets and aliens
if (CollisionManager::collidesWith(bullet, *i) && i->isAlive())
{
i->kill();
//enemyList->erase(i); // issue here, we are trying to do this in order to get rid of rendering problems .. shit just move it out of way
//i->setLocation(700.f, 10.f);
bullet.kill();
bullet.setLocation(700.f, 0.f); // temporary solution for dealing with not actually killing but stop drawing bullet
// without above line, the bullet will not be drawn but still exist on screen
}
/*
v.erase(std::remove_if(v.begin(), v.end(), //erase returns it, so it = erase
[](int i) { return i < 10; }), v.end());
*/
}
}
// ** end of if server
int deadEnemies = 0;
for (std::vector<Enemy>::iterator i = enemyList->begin(); i != enemyList->end(); ++i) {
if (!(i->isAlive())) {
deadEnemies++;
}
if (deadEnemies >= NUMBER_OF_ALIENS) {
std::cout << "You win!" << std::endl;
return 0; // Set state win
}
}
//std::cout << "Total Dead Enemies - " << deadEnemies << std::endl;
//for (Enemy& enemy : enemyList) {
// if (enemy.isAlive()) {
// enemy.draw(window);
// }
//}
//enemy.render(alienArray, mWindow);
/*
for (int i = 0; i < mEnemies.size(); i++)
{
sf::Sprite temp = mEnemies.at(i);
mWindow.draw(temp);
}
*/
// Render All
// Remember draw order is important
window.clear();
window.draw(mBackground);
window.draw(mPlayer);
window.draw(mStatisticsText);
for (std::vector<Enemy>::iterator i = enemyList->begin(); i != enemyList->end(); ++i) {
if (i->isAlive()) {
i->draw(window);
//std::cout << "Enemy " << i->getID() << " position - " << i->getLocation().x << " " << i->getLocation().y << std::endl;
}
}
if (bullet.isAlive()) // && !gameOver // for game state and win / lose screen representation
{
//draw bullet
bullet.draw(window);
//move bullet
bullet.getSprite().move(0.f, -20);
}
//test collision with bullet and boundary
if (bullet.getSprite().getPosition().y < 0)
bullet.kill();
window.display();
} // end of main second if
}
return 0;
}