Rectangle drawing function GLSL

DrawRect.frag

//all params in normalized units
vec3 drawRect(in vec2 st,
              in vec2 center,
              in float width,
              in float height,
              in float thickness,
              in vec3 fillColor, 
              in vec3 strokeColor)
{
    vec3 color = vec3(0);
    
    float halfWidth = width * .5;
    float halfHeight = height * .5;
    float halfTickness = thickness * .5;
    
    vec2 bottomLeft = vec2(center.x - halfWidth, center.y - halfHeight);
    vec2 topRight = vec2(center.x + halfWidth, center.y + halfHeight);
    
    //STROKE
    vec2 stroke = vec2(0.0);
    stroke += step(bottomLeft-halfTickness, st) * (1.0 - step(bottomLeft+halfTickness, st));
    stroke += step(topRight-halfTickness, st) * (1.0 - step(topRight+halfTickness, st));
    vec2 strokeLimit = step(bottomLeft-halfTickness, st) * (1.0 - step(topRight+halfTickness, st));
    stroke *= strokeLimit.x * strokeLimit.y;

    color = mix (color, strokeColor, min(stroke.x + stroke.y, 1.0));
    //
    
    //FILL
    vec2 fill = vec2(0.0);
    fill += step(bottomLeft+halfTickness, st) * (1.0 - step(topRight-halfTickness, st));
    vec2 fillLimit = step(bottomLeft+halfTickness, st) * (1.0 - step(topRight-halfTickness, st));
    fill *=  fillLimit.x * fillLimit.y;
    
    color = mix (color, fillColor, min(fill.x + fill.y, 1.0));
    //

	  return color;
}