The Mojolicious Blog.

A semi-official blog dedicated to the Mojolicious web framework

Day 14: A Practical Example of Mojo::DOM

A typical industrial platform model overlaid with a laser scan

With recent versions of Mojolicious, Mojo::DOM gained a lot of power that I have been excited to try, but haven't had the time for. Recently, I had a problem at my real job (in Engineering, Procurement, and Construction, or EPC for short) that I solved with Mojo::DOM (and other parts of Mojolicious) in a very short time – including learning how to use Mojo::DOM, which I had never done before.

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Day 21: Virtual(ly a) Lumberjack

Woman wearing VR goggles outside

What do you do when you want to split up a stream of data in real-time while giving the user instructions?

This is just what I wanted to do to aid in reverse-engineering the USB protocol of Virtual Reality devices known as Head Mounted Displays (HMD), for the OpenHMD project.

HMDs are used to create virtual reality environments. When worn, two slightly different images are drawn to each side of the screen, with each side visible to only one eye. This imitates binocular vision and creates an image with a feeling of depth. By tracking the rotation of the unit, the user can then look around this environment.

The recent resurgence of Virtual Reality devices can be attributed to the Rift DK1, released by Oculus in March 2013.

By logging the packets generated during each movement, we can compare the content of each log to identify which bytes are related to which action. Such movements include roll (tilting head side-to-side), pitch (looking up and down) and yaw (turning left/right). Though position isn't tracked, we also look for sway (left-right translation), surge (back and forth) and heave (up and down) information as this is used in combination with the other values for accurate tracking of rotation.

Mojo is an amazing toolkit for web development, as shown in previous calendar entries, but using components of it can also solve problems in other non-web spaces like these. Why use Mojo for this? Because it makes it easy.

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