Moving Rectangle in SFML, how to make it smoother? - c++

Question

This is my code:
#include <SFML/Graphics.hpp>
#include <iostream>
#include <Windows.h>
int main()
{
sf::RenderWindow window(sf::VideoMode(800, 600), "SFML Game");
window.setFramerateLimit(200);
//Variable that keeps the game loop running
bool play = true;
//Event object holding all events
sf::Event event;
//States for button/events
bool Left = false;
bool Right = false;
bool space = false;
//Variables
int rectXPosition = 375; //Rectangles X position
int rectYPosition = 400; //Rectangles Y position
//Images
sf::Texture image1;
if (image1.loadFromFile("Images/GreekSoldier.png") == -1)
{
std::cout << "FAILED!!!" << "\n";
return 1;
}
//Render shapes
sf::RectangleShape rect;
rect.setSize(sf::Vector2f(77, 150)); //Width and height
rect.setPosition(375, 400); //Position
rect.setFillColor(sf::Color::White); //Color
rect.setTexture(&image1);
//Game loop
while (play == true)
{
//EVENTS
while (window.pollEvent(event))
{
if (event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::Left)
{
//Set the state to true
Left = true;
}
if (event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::Right)
{
Right = true;
}
if (event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::Space)
{
space = true;
}
//Event type is window closed
if (event.type == sf::Event::Closed)
{
//Set play to false in order to stop the game loop
play = false;
}
}
//LOGIC
if (Left == true)
{
int x = 0;
for (x = 1; x < 2; x++)
{
rectXPosition-=5; //X position variable of the rectangle
rect.setPosition(rectXPosition, rectYPosition);
window.clear();
window.draw(rect);
window.display();
Sleep(5);
}
Left = false;
}
if (Right == true)
{
int x = 0;
for (x = 1; x < 2; x++)
{
rectXPosition+= 5; //X position variable of the rectangle
rect.setPosition(rectXPosition, rectYPosition);
window.clear();
window.draw(rect);
window.display();
Sleep(5);
}
Right = false;
}
if (space == true)
{
int x = 0;
for (x = 1; x < 15; x++)
{
rectYPosition-= 3; //X position variable of the rectangle
rect.setPosition(rectXPosition, rectYPosition);
window.clear();
window.draw(rect);
window.display();
Sleep(10);
}
for (x = 1; x < 15; x++)
{
rectYPosition+= 3; //X position variable of the rectangle
rect.setPosition(rectXPosition, rectYPosition);
window.clear();
window.draw(rect);
window.display();
Sleep(10);
}
space = false;
}
//RENDERING
window.clear();
//Draw the rectangle shape
window.draw(rect);
window.display();
}
//Clean up and close the window
window.close();
return 0;
}
How would I make the movement more smoother? How do I make it so the rectangle(the soldier) can jump and move at the same time? And how do I stop it so, when holding down left it doesn't take 3 seconds for it to actually move?
I've added a youtube video if you guys can't be bothered to compile it and just want to see what I'm talking about.
https://www.youtube.com/watch?v=g_JLwGh1Wgo

Answer 1

The KeyPressed events are generated when someone presses a key and then repeat every so often (but not every frame, which makes it not smooth). They are intended to be used for text input, for example.
Pressing another key will also interrupt the repetition of the events for the previous key, so your other problem has the same cause.
You should handle the KeyPressed events only for some instant actions, like pressing a menu button. In this particular example you should get rid of this altogether and use only sf::Keyboard by replacing the line:
if (Left == true)
with:
if (sf::Keyboard::isKeyPressed(sf::Keyboard::Left))
and so on...
I would explain why sf::Keyboard is the right thing here, but the documentation does it very well.
Another big problem is that you have multiple loops that don't let anything else happen in the game. You should get yourself familiar with the concepts of event loops, velocity and gravity (and make corresponding variables).
When the player presses Space you shouldn't hardcode the character to move N pixels up and N pixels down while stopping every other possible action in the game, but instead change the character's vertical velocity and use it to change the character's position in every frame (and also have that velocity be reduced by gravity).
The most important point to take from this is you must have only 1 main event loop that calls window.display.