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## Barclaycard "Waterslide"

January 2011

Role: TD

VFX: The Mill

Director: Peter Thwaites

Production Company: Gorgeous

Agency: BBH

Awards: APA Showcase Top 40 - Diamond

An old classic and one of my all time favourite commercials. The comic timing when he gets stuck on the slide in the library is perfect.

My role on this was to help with the construction of the waterslides. For details, see further down this page.

## Making Pipes

Not every project I've worked on has had the luxury of having some time up front for R & D. Definitely the exception rather than the rule! However, I had some time up front on this job to try a few things out.

We figured early on that having a quick way to lay down pipes and experiment with layouts would be beneficial.

Below you can see my first attempt in Houdini. This system takes a curve and a kit of tube parts as input, So for example, there might be a set of bends at 15º, 30º, 45º, and 90º angles, and 2 or 3 straight sections of various lengths. Based on a curve input, it would then undergo a section-by-section fitting of the parts to the curve.

The implementation was achieved using mostly VEX. It would measure the error for all the possible solutions and choose the one with the least deviation. For additional accuracy, it would check combinations of two sections at a time as a "look ahead" which significantly improved the accuracy.

In the end, we didn't go with it because it was hard to art direct. The other problem was that, given a straight section, it would tend to snake back and forth around the guide curve. Clearly not ideal for running down buildings with flat sides!

(It would be interesting to revisit this problem. I imagine one could use perfectly straight tubes for the straight parts of the guide curve, and then use some sort of optimisation algorithm to calculate the best way to join the segments.)

After that initial R&D, we decided to look for a solution directly inside XSI. This approach was completely user driven, and let artists lay down each pipe sequentially and easily adjust the rotation angle each time. It featured a "video playbar" style control that let the user rewind their current selection along the pipe so that they could insert and delete tubes at any point. The other feature was that it allowed the addition of support structures to make it appear fixed to walls or the ground.

The image below shows the tool at work. The sections of geometry you're seeing being placed were all low poly reference models and were swapped out at render time for final production quality assets.

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