in vec3 v_position;
out vec4 fragcolor;

void main() {
    float depth = length(v_position) / 20;

    float moment1 = depth;
    float moment2 = depth * depth;
    
    float dx = dFdx(depth);
    float dy = dFdy(depth);
    moment2 += 0.25*(dx*dx+dy*dy);
    fragcolor = vec4( moment1, moment2, 0.0, 1.0);
}