Computer generated heroes come in all shapes and sizes - even a cowboy chameleon voiced by Johnny Depp.

I think I must be some kind of gawping rube when it comes to computer generated animation; it seems that every time I go along to see one I'm taken by surprise by how magnificent it is.

So, with that proviso, let me say that the animation in this western tale of a chameleon (voiced by Johnny Depp) who wanders into town and decides to pass himself off as a famous gunslinger is the most awe inspiring I've seen (or maybe it's because this is the first animation for ages not released in 3D.)

This is all the more impressive given that it is a first attempt by Industrial Light and Magic, the company formed by George Lucas which has had a monopolistic dominance over film special effects since the first Star Wars films.

It's clear that Pixar is no longer at the forefront technically, though the rest are still struggling to make films that inspire the same levels of affection and pleasure.

All these films try to offer the 'something for the grown ups, something for the kids' deal but Rango misjudges the ratio. A parody of spaghetti westerns is an odd starting point for a children's film: to then load it up with references to Chinatown, hunter S Thompson and Carlos Castaneda suggests that the makers were amusing themselves primarily.

The spirit of indulgence is extended to Depp who seems to have been encouraged to showboat in the style of his Pirates of the Caribbean performances. for the most part it works very well but he does conjure up an opening scene every bit as self satisfied and unenticing as the one which opens The Social Network.

Young children are likely to find it all a little mystifying no matter how appealing the animated animal cast is. But older audiences should be swept along by its visual energy and invention.

Rango (PG)

Director: Gore Verbinski

With the voices of Johnny Depp, Isla Fisher, Abigail Breslin, Ned Beatty

Length: 107 mins

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