draw-line.frag

// Draw Line https://www.shadertoy.com/view/4ljfRD

float drawLine (vec2 p1, vec2 p2, vec2 uv, float a)
{
    float r = 0.;
    float one_px = 1. / iResolution.x; //not really one px
    
    // get dist between points
    float d = distance(p1, p2);
    
    // get dist between current pixel and p1
    float duv = distance(p1, uv);

    //if point is on line, according to dist, it should match current uv 
    r = 1.-floor(1.-(a*one_px)+distance (mix(p1, p2, clamp(duv/d, 0., 1.)),  uv));
    
    r = max(0.,r); // added ikekou
        
    return r;
}