void main()
{
    //Resolution for scaling
    vec3 r = vec3(u_resolution, 1),
    //Camera Position (approximately vec3(8,3,4.5))
    p = 13.5/r,
    //Absolute position
    a;
    
    //Iterate 30 times and set color
    for(;r.z++<4e1;)
        //Raymarch with box and sphere SDF
        p += vec3(gl_FragCoord.xy*2.-r.xy,-r)/r.x * (1.-max(a=abs(p),max(a.y,-p.z)).x);
           
    //Top light
    gl_FragColor = vec4((.01/length(max(a.xz/.2-p.y,.01))+vec3(.2,.2,.3))*(cos(u_time/.1+cos(u_time*17.))+1.)/dot(p,p),9);
}

//created by firstuser at shadergrounds.com