Team coloring in SFML

[stefanhendriks]

Hello,

This is my first post, regarding SFML so please bear with me

At this moment I am working on my project http://dune2themaker.fundynamic.com/ (Dune II - The Maker) using SDL 1.2, and I am strongly considering using SFML instead while we haven't gone too far yet. The only thing I can't seem to figure out how to do with SFML is to do team coloring.

We manipulate the palette of surfaces to draw the correct team. But in SFML there does not seem to be such a thing as a palette. So the question is: How do you apply team coloring then? Is there any other way that is adviced?

Regards,

Stefan

[Kojay]

sf::Color can be constructed from rgb values, therefore it's possible to manipulate the colors via arithmetic.

Alternatively, a simple function like this would do:

sf::Color getColor(const Team& team){
    if (team==Team1) return sf::Color::Red;
    if (team==Team2) return sf::Color::Blue;
    etc
}
 

[stefanhendriks]

what color are you changing then when drawing? The default color of a unit is red. How will returning an sf::Color::Blue make the unit have a blue shade?

[Ixrec]

Have you looked at Sprite::setColor?

void sf::Sprite::setColor   (   const Color &    color   )   
Set the global color of the sprite.

This color is modulated (multiplied) with the sprite's texture. It can be used to colorize the sprite, or change its global opacity. By default, the sprite's color is opaque white.

[Polyfructol]

Sprite::setColor will not achieve the same effect as a palette would. But fortunately, SFML supports shaders, and the palette "effect" could be achieved with shader.

On the OpenGL website : http://www.opengl.org/wiki/Common_Mistakes#Paletted_textures

//Fragment shader
#version 110
uniform sampler2D ColorTable;     //256 x 1 pixels
uniform sampler2D MyIndexTexture;
varying vec2 TexCoord0;
 
void main()
{
  //What color do we want to index?
  vec4 myindex = texture2D(MyIndexTexture, TexCoord0);
  //Do a dependency texture read
  vec4 texel = texture2D(ColorTable, myindex.xy);
  gl_FragColor = texel;   //Output the color
}

So you need to create an indexed texture and a palette texture.

[Kojay]

Though I 'm not certain what exactly is it that SDL palette does, I could see manipulating the pixels of a sf::Image instead:

sf::Image trikeImage;
trikeImage.loadFromFile("graphics/Unit_Trike.bmp");
sf::Vector2u trikeSize = trikeImage.getSize();

sf::Image trikeGreen;
trikeGreen.create(trikeSize.x, trikeSize.y);
sf::Image trikeBlue;
trikeBlue.create(trikeSize.x, trikeSize.y);

for (int i=0; i<trikeSize.x; ++i){
    for (int j=0; j<trikeSize.y; ++j){
        sf::Color pixelColor = trikeImage.getPixel(i,j);
        sf::Color bluePixel(pixelColor);
        sf::Color greenPixel(pixelColor);
        if ((pixelColor == sf::Color(125,0,0))
            ||(pixelColor == sf::Color(214,0,0))
            ||(pixelColor == sf::Color(60,0,0))
            ||(pixelColor == sf::Color(89,0,0))
            ||(pixelColor == sf::Color(153,0,0))
            ||(pixelColor == sf::Color(182,0,0))
            )
        {
            greenPixel = sf::Color(0,pixelColor.g+pixelColor.r,pixelColor.b, pixelColor.a);
            bluePixel = sf::Color(0,pixelColor.g,pixelColor.b+pixelColor.r, pixelColor.a);
        }
        trikeGreen.setPixel(i,j,greenPixel);
        trikeBlue.setPixel(i,j,bluePixel);
    }
}
 

[stefanhendriks]

thats exactly what i meant, nice!