Messages

1

General / Re: Nested pollEvent spikes CPU

« on: June 16, 2015, 01:36:17 am »

Ah ha! I think I have the solution you pointed me to. The code below behaves the same as the code in my original post (as far as I can tell), but without the CPU spike:

#include <SFML/Graphics.hpp>
#include "ResourcePath.hpp"

int main() {
    sf::RenderWindow window(sf::VideoMode(480, 320), "SFML Window");
    window.setFramerateLimit(20);

    sf::Font font;
    if (!font.loadFromFile(resourcePath() + "sansation.ttf")) {
        return 0;
    }
    sf::Text text;
    text.setFont(font);
    text.setCharacterSize(50);
    text.setStyle(sf::Text::Regular);
    text.setColor(sf::Color::Blue);

    while (window.isOpen()) {
        text.setString("Hello SFML");
        window.clear();
        window.draw(text);
        window.display();
       
        bool spacePressed = false;

        sf::Event event;
        while (window.pollEvent(event) || spacePressed == true) {

            if (event.type == sf::Event::Closed) {
                window.close();
                exit(0);
            }

            if (event.type == sf::Event::KeyPressed || spacePressed == true) {
               
                if (event.key.code == sf::Keyboard::Space || spacePressed == true) {
                    spacePressed = true;
                    text.setString("You pressed space");
                    window.clear();
                    window.draw(text);
                    window.display();
                }
               
                if (event.key.code == sf::Keyboard::Escape) {
                    spacePressed = false;
                }
            }
        }
    }
    return 0;
}
 

This code has less "x-mas trees" too (I haven't seen that term before). I'm curious about that. Is the issue with too many "x-mas trees" that it looks ugly and it's easy to make mistakes in, or is there something else that causes this to be an indicator of a problem?

I appreciate all the help. Thank you!

2

General / Re: Nested pollEvent spikes CPU

« on: June 15, 2015, 11:49:24 am »

Thank you for the quick and friendly reply!

Is this the tutorial you're referring to? http://www.sfml-dev.org/tutorials/2.0/window-events.php

I'd like to find more information about using the "states" you referred to.

Not checking for KeyPressed in the second loop was a silly mistake when I shrunk my code down into the snippet above. I'll correct that in my OP.

3

General / Nested pollEvent spikes CPU

« on: June 15, 2015, 10:44:14 am »

Hello,

I'm having trouble drawing something in the window upon an event, holding that display, then resetting the display upon another event. I've come up with a solution, however it causes a high spike in CPU utilization. In the code snippet below, the CPU spikes and remains high when [Space] is pressed. The CPU spike goes away when [Escape] is pressed.

How can I implement a better solution for this? Any help appreciated.

#include <SFML/Graphics.hpp>
#include "ResourcePath.hpp"

int main() {
    sf::RenderWindow window(sf::VideoMode(480, 320), "SFML Window");
    window.setFramerateLimit(20);

    sf::Font font;
    if (!font.loadFromFile(resourcePath() + "sansation.ttf")) {
        return 0;
    }
    sf::Text text;
    text.setFont(font);
    text.setCharacterSize(50);
    text.setStyle(sf::Text::Regular);
    text.setColor(sf::Color::Blue);

    while (window.isOpen()) {
        window.clear();
       
        text.setString("Hello SFML");
        window.draw(text);
       
        window.display();

        sf::Event event;
        while (window.pollEvent(event)) {

            if (event.type == sf::Event::Closed) {
                window.close();
                exit(0);
            }

            if (event.type == sf::Event::KeyPressed) {
               
                if (event.key.code == sf::Keyboard::Space) {
                    window.clear();
                   
                    text.setString("You pressed space");
                    window.draw(text);
                   
                    window.display();
                   
                    bool wait = true;
                    while(wait) {
                   
                        while (window.pollEvent(event)) {
                            if (event.type == sf::Event::Closed) {
                                window.close();
                                exit(0);
                            }
                           
                            if (event.type == sf::Event::KeyPressed) {
                                if (event.key.code == sf::Keyboard::Escape) {
                                    wait = false;
                                }
                            }
                        }
                    }
                }
            }
        }
    }
    return 0;
}