Topics

1

Graphics / Starting With OpenGL

« on: January 06, 2014, 12:00:42 am »

I am attempting to run the first example on the openGL tutorial.

http://sfml-dev.org/tutorials/2.1/window-opengl.php

I receive errors as follows:

1>main.obj : error LNK2019: unresolved external symbol __imp__glClear@4 referenced in function _main
1>main.obj : error LNK2019: unresolved external symbol __imp__glViewport@16 referenced in function _main

I believe there is a file named opengl32.lib that I have to do something with. Some of the guides tell me the location, so maybe I need to copy it to my project? Some tell me things about other libraries like glu and ones I obviously don't need like glut. And finally there are a few tutorials telling me that I can put a linker option (which I assume goes in Linker command line options). Nothing I try is working and I'm getting very frustrating and I have over a hundred tabs of tutorials I've tried and I don't know why this is so complicated.

I am using Microsoft Visual C++ 2010.

2

Graphics / Build a Realistic Sphere

« on: January 05, 2014, 07:44:48 pm »

I am currently able to build nice beautiful circles like this:

void resetPlanetVertexes (sf::VertexArray* planet, sf::Vector2f* center, float size, sf::Color* color)
{
        int i;
        int count = (int)(planet->getVertexCount());
        for (i = 1; i < count-1; i ++) {
                float angle = ((float)(i) / (float)(count-2) * 360.f) * 3.14f / 180.f;
                ((*planet)[i]).position = *center + sf::Vector2f(
                        (float)(std::cos(angle) * size),
                        (float)(std::sin(angle) * size)
                );
                ((*planet)[i]).color = *color;
        }
        ((*planet)[count-1]).position = ((*planet)[1]).position;
        ((*planet)[count-1]).color = ((*planet)[1]).color;
}

void buildPlanet (sf::VertexArray* planet, sf::RenderWindow* window)
{
        int width = (int)(window->getSize().x);
        int height = (int)(window->getSize().y);
        sf::Color planetcolor = getPlanetColor();
        float size = getPlanetSize();
        std::cout << "Planet Size: " << size << std::endl;
        sf::Vertex* planetcenter = &((*planet)[0]);
        planetcenter->position = sf::Vector2f
                                ((float)(rand() % (width + (PLANET_BORDER<<1)))-PLANET_BORDER,
                                (float)(rand() % (height + (PLANET_BORDER<<1)))-PLANET_BORDER);
        planetcenter->color = planetcolor;
        resetPlanetVertexes(planet, &(planetcenter->position), size, &(planetcenter->color));
}

However, they look obviously flat and not like planets at all. They look like someone cut perfect circles out of construction paper.



If we look at a planet like Neptune, we see that the bottom right fades towards black, while the top left fades towards a slightly brighter color to create the appearance of a sphere and not a circle.

I think I can probably do something with the coloring to darken or lighten it. (Not sure the best way to do that.) Do I really have to modify each of the three rgb values to lighten/darken a colour?

I also thought there might be a way to build a 3D planet or something similar to that as well.

I want to make each planet random and different so I don't want to use a standard sprite.

3

SFML website / Think This Is A Typo

« on: January 03, 2014, 11:28:06 pm »

On this page:
http://www.sfml-dev.org/tutorials/2.0/graphics-draw.php

You have this text in the Off-screen drawing section:

sf::Texture& texture = renderTexture.getTexture();

// draw it to the window
sf::Sprite sprite(texture);

I think the ampersand is a typo.

4

Graphics / Failing To Load Font

« on: January 03, 2014, 10:52:12 pm »

My program:

int main()
{
        sf::Font font;
        if (!font.loadFromFile("Xolonium-Regular.otf"))
        {
                // error...
        }
    sf::RenderWindow window(sf::VideoMode::getDesktopMode(), "SFML works!", sf::Style::Fullscreen);
        window.setVerticalSyncEnabled(true);

        sf::Text title;
        title.setFont(font); // font is a sf::Font
        title.setString("Hello World!");
        title.setCharacterSize(64); // in pixels, not points!
        title.setColor(sf::Color::White);

    while (window.isOpen())
    {
        sf::Event event;
        while (window.pollEvent(event))
        {
                        switch (event.type)
                        {
                                case sf::Event::KeyPressed: //Key pressed
                                        switch (event.key.code)
                                        {
                                        case sf::Keyboard::Escape:
                                                window.close();
                                                break;
                                        }
                                        break;
                        }
        }

        // clear the window with black color
        window.clear(sf::Color::Black);
               
        window.draw(title);
        window.display();
    }

    return 0;
}

Displays this weird text in the command prompt:



And displays this dialog:



According to this thread, OTF format should be supported:
http://en.sfml-dev.org/forums/index.php?topic=72.0

When I open the font it works fine to view in Windows. It's a font that's available on this site here:
http://www.fontspace.com/severin-meyer/xolonium

The font is in the same directory as sfml-graphics-2.dll and others... which I assume is the correct directory. It seems awfully strange if this is simply failing to find the file.

5

Graphics / Creating Large Number Of Stars Efficiently

« on: January 03, 2014, 10:15:23 pm »

I'm hoping to create a background which is randomized with lots of stars for a space-themed game. The stars all move in the same direction at the same time to simulate motion. There will be a lot of them, and I'd really like to create an efficient system.

I want it randomized, so it's not the same graphic over and over. What is the most efficient way to do this?

Do I want to create an array of star objects, similar to this code which doesn't work:

sf::CircleShape stars[] = sf::CircleShape[500];

Or is it recommended to do something more fancy, such as creating a random Image on the fly which is then moved in one piece?