This is a style to visualize the presence of simple roof tags on certain types of buildings. It helps mapping buildings for Simple 3D visualization from aerial views.

meta   
{
        title: "Simple roof tags";
        author: "heilbron"; 
        version: "1.14_2021-06-21"; 
        description: "Visualize the presence of some simple roof tags (shape & colour)";
        /* link: "http://josm.openstreetmap.de/wiki/Styles/SimpleRoofTags"; */
        watch-modified: true;
}
        
area[building]
{
        z-index: 1;
        fill-opacity: 0.03; /* let the background, i.e. the roof, be recognizable */
}

area[building]["roof:colour"]
{
        z-index: 1;
        opacity: 0.9;
        color: (tag("roof:colour")); /* if a color is set, use it to color the outline ... */
}

area[building]["roof:colour"=red]
{
        z-index: 1;
        color: #A54040; /* ... but make red (#FF0000) a mixture of  brown and red */
        opacity: 0.7;   /* less intrusive */
}

area[building]["roof:colour"=lightgrey]
{
        color: #C8C8C8; /* ... but make lightgrey (#D3D3D3) a little darker*/
}

area[building]["roof:colour"=grey]
{
        color: #A0A0A0; /* ... but make grey (#BEBEBE) a little darker*/
}

area[building]["roof:colour"=darkgrey]
{
        color: #505050; /* ... but make darkgrey (#A9A9A9) quite darker*/
}

area[building]["roof:colour"=brown]
{
        color: #802020; /* ... but make brown (#A52A2A) darker*/
}

area[building][!"roof:colour"]
{
        z-index: 1;
        color: #101010; /* no roof colour => make the outline almost black */
}


area|z17-[building][!"roof:shape"] /* no roof shape set? => dash the outline */
{
        z-index: 1;
        width: 4;
        dashes: 3,3;
        icon-image: url('help.png');
        shield-image: url("fills/grass.png");
}

area|z17-[building=~/garage.*/] /* ignore roof tags for garages, i.e. make them all look the same */
{
        z-index: 0;
        width: 2;
        dashes: 8,1;
        color: #282828;
        shield-color: blue
        shield-color: #0000FF;
        shield-opacity: 0.5;
        shield-frame-color: black;
        shield-frame-width:2;
        shield-casing-color: white;
        shield-casing-width: 2;
        shield-text: (tag("roof:colour"));
        /* shield-image:url('fills/grass.png'); */
        shield-shape: rounded;
}

area[building]["roof:shape"]
{
        z-index: 1;
        width: 5;
}

Styles_SimpleRoofTags-style.mapcss, Styles_SimpleRoofTags.zip