TheNextWeek: Unused variables in Perlin noise

[Krenodeno]

In listing 29, function noise(), we first calculate u, v and w from p.x, p.y and p.z but then do nothing with them.

        double noise(const point3& p) const {
            auto u = p.x() - floor(p.x());
            auto v = p.y() - floor(p.y());
            auto w = p.z() - floor(p.z());

            auto i = static_cast<int>(4*p.x()) & 255;
            auto j = static_cast<int>(4*p.y()) & 255;
            auto k = static_cast<int>(4*p.z()) & 255;

            return ranfloat[perm_x[i] ^ perm_y[j] ^ perm_z[k]];
        }