Messages

1

General / Re: Frames at the time

« on: September 11, 2014, 10:28:09 am »

Thank you Laurent and FRex, i fixed timestep in my game, and now it works exactly how i wanted. The same speed with different frame rates, clear code, no bugs like objects falling through the floor or disappearing when i move the window, also clear physics, no matter if the frame rate is 5 or 500 FPS. Here's the source code of my game object:

Game::Game(void)
: window(sf::VideoMode(window_size_x, window_size_y), "Ambient"),
view(sf::FloatRect(0, 0, float(window_size_x), float(window_size_y))),
updateFPS(1000),
dt(1.0f / updateFPS),
elapsedTime(0.0f),
accumulator(0.0f),
currentTime(clock.getElapsedTime().asMilliseconds())
{
        init();
}
 

And game run() function:

void Game::run()
{
        while (window.isOpen())
        {
                /* Events */
                EventHandling();

                /* Timestep */
                newTime = clock.getElapsedTime().asMilliseconds();
                frameTime = static_cast<float> (newTime - currentTime) / 1000.0f;
                if (frameTime > 0.25f) frameTime = 0.25f;
                currentTime = newTime;
                accumulator += frameTime;
                while (accumulator >= dt)
                {
                        elapsedTime += dt;
                        accumulator -= dt;
                        /* Game Logic Update */
                        GameLogicUpdate();
                }

                /* View */
                View();

                /* Draw */
                Draw();
        }
}

Problem solved.

2

General / Frames at the time

« on: September 04, 2014, 10:08:55 am »

Hello, i've been working on a game project recently, and i already implemented some stuff, i have collisions, entities, bullets, movable camera. But after all this, i am still wondering about how to handle frames per second. Right now my code works on a simple principle, it measures the time of each frame and move the objects with constant speed multiplayed by that time:

float delta = clock.restart().asSeconds();
...
hero.sprite.move(hero.h_speed * delta, hero.gravity_delta * delta);

Works? Works. But looks a little poor, becouse i have to keep an eye on every single movement instruction and i'm pretty sure it could be done better. I've already tried the "update()" method which updates all the game logic by a constant time, but i don't like it, becouse i have to set the FPS limit then, and if the PC isn't good enough to handle it, the game works slower. How do all of these big games do it? I'd like to implement a method which will let me to keep the game logic in one separate function, but also does not force me to set the constant FPS and works with exact same speed on every computer, no matter if it's 15 or 150 FPS.

3

Graphics / Re: Bounding box collision problem

« on: July 31, 2014, 01:53:39 pm »

Thanks for the advices, i modified the code a little bit. Now it looks less nebwie But still don't know how to implement proper moving during collision. It's good only for the floor, but maybe it's enough. I think i would just have to avoid building map with few separated objects in one wall. Here's the code after changes:

(click to show/hide)

#include <SFML/Graphics.hpp>
#include <cmath>
#include <iostream>

#define window_size_x 1200
#define window_size_y 800
#define max_speed     1000
#define gravity       4500
#define jump_power    1500
#define friction          5000

using namespace std;

void BoxCollision(sf::Sprite & sprite_1, sf::Sprite & sprite_2, const float x, const float y, float & gravity_delta_float, float & h_speed_float, bool & jump_bool, bool & double_jump_bool)
{
        float sprite_1_top = sprite_1.getPosition().y - sprite_1.getOrigin().y;
        float sprite_1_bottom = sprite_1.getPosition().y - sprite_1.getOrigin().y + sprite_1.getTexture()->getSize().y;
        float sprite_1_left = sprite_1.getPosition().x - sprite_1.getOrigin().x;
        float sprite_1_right = sprite_1.getPosition().x - sprite_1.getOrigin().x + sprite_1.getTexture()->getSize().x;

        float sprite_1_previous_top = y - sprite_1.getOrigin().y;
        float sprite_1_previous_bottom = y - sprite_1.getOrigin().y + sprite_1.getTexture()->getSize().y;
        float sprite_1_previous_left = x - sprite_1.getOrigin().x;
        float sprite_1_previous_right = x - sprite_1.getOrigin().x + sprite_1.getTexture()->getSize().x;

        float sprite_2_top = sprite_2.getPosition().y - sprite_2.getOrigin().y;
        float sprite_2_bottom = sprite_2.getPosition().y - sprite_2.getOrigin().y + sprite_2.getTexture()->getSize().y;
        float sprite_2_left = sprite_2.getPosition().x - sprite_2.getOrigin().x;
        float sprite_2_right = sprite_2.getPosition().x - sprite_2.getOrigin().x + sprite_2.getTexture()->getSize().x;

        if (sprite_1_top < sprite_2_bottom &&
                sprite_1_bottom > sprite_2_top &&
                sprite_1_left < sprite_2_right &&
                sprite_1_right > sprite_2_left)
        {              
                sprite_2.setColor(sf::Color::Red);
                if (sprite_1_previous_top >= sprite_2_bottom)
                {
                        sprite_1.setPosition(sprite_1.getPosition().x, sprite_2_bottom + sprite_1.getOrigin().y);
                        gravity_delta_float = jump_power;
                }
                if ((sprite_1_previous_left >= sprite_2_right && sprite_1_previous_bottom <= sprite_2_top) || (sprite_1_previous_right <= sprite_2_left && sprite_1_previous_bottom <= sprite_2_top))
                        sprite_1.setPosition(sprite_1.getPosition().x, sprite_2_top - sprite_1.getTexture()->getSize().y + sprite_1.getOrigin().y);
                else
                {
                        if (sprite_1_previous_bottom <= sprite_2_top)
                        {
                                sprite_1.setPosition(sprite_1.getPosition().x, sprite_2_top - sprite_1.getTexture()->getSize().y + sprite_1.getOrigin().y);
                                gravity_delta_float = 0;
                                double_jump_bool = false;
                                jump_bool = false;
                        }
                        if (sprite_1_previous_left >= sprite_2_right)
                        {
                                sprite_1.setPosition(sprite_2_right + sprite_1.getOrigin().x, sprite_1.getPosition().y);
                                h_speed_float = 0;
                        }
                               
                        if (sprite_1_previous_right <= sprite_2_left)
                        {
                                sprite_1.setPosition(sprite_2_left - sprite_1.getTexture()->getSize().x + sprite_1.getOrigin().x, sprite_1.getPosition().y);
                                h_speed_float = 0;
                        }
                }
        }
        else
                sprite_2.setColor(sf::Color::White);
}

int main()
{
        /* Window */
        sf::RenderWindow window(sf::VideoMode(window_size_x, window_size_y), "Ambient");
        //window.setVerticalSyncEnabled(true);
        //window.setFramerateLimit(10);

        /* Textures */
        sf::Texture background_texture;
                background_texture.loadFromFile("Scene.png");
        sf::Texture box_texture;
                box_texture.loadFromFile("Box_1.png");
        sf::Texture triangle_texture;
                triangle_texture.loadFromFile("Triangle.png");

        /* Sprites */
        sf::Sprite background;
                background.setTexture(background_texture);
                background.setPosition(window_size_x / 2.0f, window_size_y / 2.0f);
                background.setOrigin(background_texture.getSize().x / 2.0f, background_texture.getSize().y / 2.0f);    
        std::vector <sf::Sprite> boxes;
        int amount = 20;
        int separation = 150;
        float posX = -50;
        float posY = 50;
        for (int i = 0; i < amount; i++)
        {
                boxes.push_back( sf::Sprite() );
                if (i < 7) posX += separation;
                else if (i < 11) posY += separation;
                else if (i < 17) posX -= separation;
                else if (i < 20) posY -= separation;
                boxes[i].setTexture(box_texture);
                boxes[i].setPosition(posX, posY);
        }
        sf::Sprite triangle;
                triangle.setTexture(triangle_texture);
                triangle.setPosition(600, 350);
                triangle.setOrigin(triangle_texture.getSize().x / 2.0f, triangle_texture.getSize().y / 2.0f);
               
        /* Clock*/
        sf::Clock clock;

        /* Variables */
        bool left = false;
        bool right = false;
        bool jump = false;
        bool jump_pressed = false;
        bool double_jump = false;
        float h_speed = 0;
        float gravity_delta = 0;

        /* -------------------- Core of the game -------------------- */
        while (window.isOpen())
        {
                /* Time step */
                float delta = clock.restart().asSeconds();

                /* Events */
                sf::Event event;
                while (window.pollEvent(event))
                {
                        if (event.type == sf::Event::Closed || event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::Escape)
                                window.close();
                        if (event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::LControl && jump == true && double_jump == false && jump_pressed == false)
                        {
                                double_jump = true;
                                gravity_delta = 0;
                                triangle.move(0, -jump_power * delta);
                        }
                }      

                /* Previous position */
                float previous_x = triangle.getPosition().x;
                float previous_y = triangle.getPosition().y;

                /* Jump */
                if (sf::Keyboard::isKeyPressed(sf::Keyboard::LControl))
                {
                        if (gravity_delta == 0) jump = true;
                        jump_pressed = true;
                }
                else jump_pressed = false;
                if (jump == true) triangle.move(0, -jump_power * delta);

                /* Right */
                if (sf::Keyboard::isKeyPressed(sf::Keyboard::Right)) right = true;
                else right = false;
                if (right == true && h_speed < max_speed) h_speed += friction * delta;
                else if (h_speed > 0) h_speed -= friction * delta;

                /* Left */
                if (sf::Keyboard::isKeyPressed(sf::Keyboard::Left)) left = true;
                else left = false;
                if (left == true && h_speed > -max_speed) h_speed -= friction * delta;
                else if (h_speed < 0) h_speed += friction * delta;

                /* Horizontal speed reset */
                if (right == false && left == false && h_speed > -friction * delta && h_speed < friction * delta) h_speed = 0;

                /* Gravity */
                gravity_delta += gravity * delta;

                /* Move */
                triangle.move(h_speed * delta, gravity_delta * delta);

                /* Collision */
                for (unsigned int i = 0; i < boxes.size(); i++)
                        BoxCollision(triangle, boxes[i], previous_x, previous_y, gravity_delta, h_speed, jump, double_jump);

                /* Draw */
                window.clear();
                window.draw(background);
                for (const auto& box : boxes)
                        window.draw(box);
                window.draw(triangle);         
                window.display();
        }
        return 0;
}

4

Graphics / Re: Bounding box collision problem

« on: July 30, 2014, 10:18:29 pm »

Yeah, i have to learn much more, thanks for the cointainers, very helpful.

5

Graphics / Re: Bounding box collision problem

« on: July 30, 2014, 09:01:25 pm »

Well, now i'm kinda confused. I added the colors to box collision function, but it changes the color for only one sprite at the time. Even if i collide with two sprites at the same time, one of them is red, other default (only in corners it sets two sprites red). So maybe my dollision detection itn't working properly.
Here's the example of how it looks: http://scr.hu/2d0y/c6l0u
In 1 and 2 i'm pressing left/right arrows, in 3 up and right.

6

Graphics / Bounding box collision problem

« on: July 30, 2014, 09:33:16 am »

Hi, im working on a project (2D platformer game), and i'm trying to achieve proper collisions on my map. The problem is, i want my collisions to be perfect (work in every possible situation). I wrote a function which meets my expectations almost perfectly, but there is a problem with corners. When i'm trying to move in two directions at once, up and right for example, and my character meets the box corner, it stops and i can't go further until i release one of the buttons to specify the one exact direction. It only happens when im moving counter clockwise (pressing two butons, like up+right, up+left, left+down). Here's the code to visualize the problem:

(click to show/hide)

#include <SFML/Graphics.hpp>
#include <cmath>
#include <iostream>

#define window_size_x 1200
#define window_size_y 800
#define max_speed     500

using namespace std;

void BoxCollision(sf::Sprite & sprite_1, sf::Sprite & sprite_2, float x, float y)
{
        float sprite_1_top = sprite_1.getPosition().y - sprite_1.getOrigin().y;
        float sprite_1_bottom = sprite_1.getPosition().y - sprite_1.getOrigin().y + sprite_1.getTexture()->getSize().y;
        float sprite_1_left = sprite_1.getPosition().x - sprite_1.getOrigin().x;
        float sprite_1_right = sprite_1.getPosition().x - sprite_1.getOrigin().x + sprite_1.getTexture()->getSize().x;

        float sprite_1_previous_top = y - sprite_1.getOrigin().y;
        float sprite_1_previous_bottom = y - sprite_1.getOrigin().y + sprite_1.getTexture()->getSize().y;
        float sprite_1_previous_left = x - sprite_1.getOrigin().x;
        float sprite_1_previous_right = x - sprite_1.getOrigin().x + sprite_1.getTexture()->getSize().x;

        float sprite_2_top = sprite_2.getPosition().y - sprite_2.getOrigin().y;
        float sprite_2_bottom = sprite_2.getPosition().y - sprite_2.getOrigin().y + sprite_2.getTexture()->getSize().y;
        float sprite_2_left = sprite_2.getPosition().x - sprite_2.getOrigin().x;
        float sprite_2_right = sprite_2.getPosition().x - sprite_2.getOrigin().x + sprite_2.getTexture()->getSize().x;

        if (sprite_1_top < sprite_2_bottom &&
                sprite_1_bottom > sprite_2_top &&
                sprite_1_left < sprite_2_right &&
                sprite_1_right > sprite_2_left)
        {
                if (sprite_1_previous_top >= sprite_2_bottom)
                        sprite_1.setPosition(sprite_1.getPosition().x, sprite_2_bottom + sprite_1.getOrigin().y);
                if ((sprite_1_previous_left >= sprite_2_right && sprite_1_previous_bottom <= sprite_2_top) || (sprite_1_previous_right <= sprite_2_left && sprite_1_previous_bottom <= sprite_2_top))
                {
                        cout << "yep" << endl;
                        sprite_1.setPosition(sprite_1.getPosition().x, sprite_2_top - sprite_1.getTexture()->getSize().y + sprite_1.getOrigin().y);
                }
                else
                {
                        if (sprite_1_previous_bottom <= sprite_2_top)
                                sprite_1.setPosition(sprite_1.getPosition().x, sprite_2_top - sprite_1.getTexture()->getSize().y + sprite_1.getOrigin().y);
                        if (sprite_1_previous_left >= sprite_2_right)
                                sprite_1.setPosition(sprite_2_right + sprite_1.getOrigin().x, sprite_1.getPosition().y);
                        if (sprite_1_previous_right <= sprite_2_left)
                                sprite_1.setPosition(sprite_2_left - sprite_1.getTexture()->getSize().x + sprite_1.getOrigin().x, sprite_1.getPosition().y);
                }
        }
}

int main()
{
        sf::RenderWindow window(sf::VideoMode(window_size_x, window_size_y), "Ambient");
        //window.setVerticalSyncEnabled(true);
        //window.setFramerateLimit(10);

        sf::Texture background_texture;
                background_texture.loadFromFile("Scene.png");
        sf::Texture box_texture;
                box_texture.loadFromFile("Box_1.png");
        sf::Texture ramp_texture;
                ramp_texture.loadFromFile("LB.png");
        sf::Texture triangle_texture;
        triangle_texture.loadFromFile("Triangle.png");

        sf::Sprite background;
                background.setTexture(background_texture);
                background.setPosition(window_size_x / 2.0f, window_size_y / 2.0f);
                background.setOrigin(background_texture.getSize().x / 2.0f, background_texture.getSize().y / 2.0f);
        sf::Sprite box_1;
                box_1.setTexture(box_texture);
                box_1.setPosition(100, 50);
        sf::Sprite box_2;
                box_2.setTexture(box_texture);
                box_2.setPosition(250, 50);
        sf::Sprite box_3;
                box_3.setTexture(box_texture);
                box_3.setPosition(400, 50);
        sf::Sprite box_4;
                box_4.setTexture(box_texture);
                box_4.setPosition(550, 50);
        sf::Sprite box_5;
                box_5.setTexture(box_texture);
                box_5.setPosition(700, 50);
        sf::Sprite box_6;
                box_6.setTexture(box_texture);
                box_6.setPosition(850, 50);
        sf::Sprite box_7;
                box_7.setTexture(box_texture);
                box_7.setPosition(1000, 50);
        sf::Sprite box_8;
                box_8.setTexture(box_texture);
                box_8.setPosition(1000, 200);
        sf::Sprite box_9;
                box_9.setTexture(box_texture);
                box_9.setPosition(1000, 350);
        sf::Sprite box_10;
                box_10.setTexture(box_texture);
                box_10.setPosition(1000, 500);
        sf::Sprite box_11;
                box_11.setTexture(box_texture);
                box_11.setPosition(1000, 650);
        sf::Sprite box_12;
                box_12.setTexture(box_texture);
                box_12.setPosition(850, 650);
        sf::Sprite box_13;
                box_13.setTexture(box_texture);
                box_13.setPosition(700, 650);
        sf::Sprite box_14;
                box_14.setTexture(box_texture);
                box_14.setPosition(550, 650);
        sf::Sprite box_15;
                box_15.setTexture(box_texture);
                box_15.setPosition(400, 650);
        sf::Sprite box_16;
                box_16.setTexture(box_texture);
                box_16.setPosition(250, 650);
        sf::Sprite box_17;
                box_17.setTexture(box_texture);
                box_17.setPosition(100, 650);
        sf::Sprite box_18;
                box_18.setTexture(box_texture);
                box_18.setPosition(100, 500);
        sf::Sprite box_19;
                box_19.setTexture(box_texture);
                box_19.setPosition(100, 350);
        sf::Sprite box_20;
                box_20.setTexture(box_texture);
                box_20.setPosition(100, 200);
        sf::Sprite ramp;
                ramp.setTexture(ramp_texture);
                ramp.setPosition(550, 400);
        sf::Sprite triangle;
                triangle.setTexture(triangle_texture);
                triangle.setPosition(600, 350);
                triangle.setOrigin(triangle_texture.getSize().x / 2.0f, triangle_texture.getSize().y / 2.0f);

        sf::Clock clock;

        float delta = 0;
        float previous_x = 0;
        float previous_y = 0;

        while (window.isOpen())
        {
                delta = clock.restart().asSeconds();

                sf::Event event;
                while (window.pollEvent(event))
                {
                        if (event.type == sf::Event::Closed || event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::Escape)
                                window.close();
                }      

                previous_x = triangle.getPosition().x;
                previous_y = triangle.getPosition().y;
                if (sf::Keyboard::isKeyPressed(sf::Keyboard::Up)) triangle.move(0, -max_speed  * delta);
                if (sf::Keyboard::isKeyPressed(sf::Keyboard::Down)) triangle.move(0, max_speed  * delta);
                if (sf::Keyboard::isKeyPressed(sf::Keyboard::Left)) triangle.move(-max_speed * delta, 0);
                if (sf::Keyboard::isKeyPressed(sf::Keyboard::Right)) triangle.move(max_speed * delta, 0);

                BoxCollision(triangle, box_1, previous_x, previous_y);
                BoxCollision(triangle, box_2, previous_x, previous_y);
                BoxCollision(triangle, box_3, previous_x, previous_y);
                BoxCollision(triangle, box_4, previous_x, previous_y);
                BoxCollision(triangle, box_5, previous_x, previous_y);
                BoxCollision(triangle, box_6, previous_x, previous_y);
                BoxCollision(triangle, box_7, previous_x, previous_y);
                BoxCollision(triangle, box_8, previous_x, previous_y);
                BoxCollision(triangle, box_9, previous_x, previous_y);
                BoxCollision(triangle, box_10, previous_x, previous_y);
                BoxCollision(triangle, box_11, previous_x, previous_y);
                BoxCollision(triangle, box_12, previous_x, previous_y);
                BoxCollision(triangle, box_13, previous_x, previous_y);
                BoxCollision(triangle, box_14, previous_x, previous_y);
                BoxCollision(triangle, box_15, previous_x, previous_y);
                BoxCollision(triangle, box_16, previous_x, previous_y);
                BoxCollision(triangle, box_17, previous_x, previous_y);
                BoxCollision(triangle, box_18, previous_x, previous_y);
                BoxCollision(triangle, box_19, previous_x, previous_y);
                BoxCollision(triangle, box_20, previous_x, previous_y);
               
                window.clear();
                window.draw(background);
                window.draw(box_1);
                window.draw(box_2);
                window.draw(box_3);
                window.draw(box_4);
                window.draw(box_5);
                window.draw(box_6);
                window.draw(box_7);
                window.draw(box_8);
                window.draw(box_9);
                window.draw(box_10);
                window.draw(box_11);
                window.draw(box_12);
                window.draw(box_13);
                window.draw(box_14);
                window.draw(box_15);
                window.draw(box_16);
                window.draw(box_17);
                window.draw(box_18);
                window.draw(box_19);
                window.draw(box_20);
                window.draw(triangle);         
                window.display();
        }
        return 0;
}

"triangle" sprite has rectangular 100x100 texture, "box" sprites also.