shader
test_color_3xv_dfloat(output color Cout = 0)
{
    float valr = 0.5*(v);
    float valg = 0.6*(v);
    float valb = 0.4*(v);
    float val2r = u;
    float val2g = 0.3*u;
    float val2b = 0.75*u;
     
              
    color c1 = color(valr, valg, valb);
    if (int(P[0]*32)%2==0) {
        color c2 = color(val2r, val2g, val2b);
        c1 = c2;
    }
            
    color dxc = Dx(c1);
    color dyc = Dy(c1);
    Cout = dxc + dyc;
    
}
