This is just a small update to share something we created while exploring Class Blueprints: Unreal Engine's approach to visual object-oriented programming. If you're familiar with the concept of objects within programming (from any language), the term class should give you a sense of how these work. A Class Blueprint is a way to build the geometry, data and behaviours/functionality of an object in Unreal Engine. After defining a class blueprint (for an Actor for example), it's possible to generate as many actors based off this class as you like.

As a quick test a few months ago, I (Thomas) decided to try and create a class blueprint around the idea of a coloured light. It would essentially be a point light with a visible sphere. Each object should be able to receive a unique colour to apply to its point light and the emissive material on the sphere to make the light source visible. Here's how the scene came out in the end...

The actual blueprint

Each Class Blueprint has an event graph to create a node-based program. Starting with the BeginPlay event (which fires once per object at runtime), a random vector is created and multiplied to appear anywhere with a 5000 unit radius from the centre. I've mapped the Z value to keep it above ground. This is all for the position of the light. To generate a random colour, a random float value is generated between 0 and 360, representing the hue spectrum. This is passed through the HSV to RGB node to create a usable colour object by UE, and it's then applied to the point light colour and emissive material of the object itself. This is identical to how the random colours were generated for the lights in this post.

Below is a live embed of the blueprint I created (thanks blueprintue.com). You can interact with right-mouse drag and scrolling.

From here

This small experiment was particularly useful coming from a background where I'm familiar with the concept of objects and class-based programming. Understanding how to generate objects in Unreal Engine and control how they manifest themselves in the scene, as well as what points of data and behaviours are available, is incredibly useful and we'll definitely be building on this for future projects and pipelines.

One of our goals with implementing Unreal Engine into the Data Arena is to create a pipeline for students of architecture, interior design, product design or any practice involving create creation of digital 3D models. A pipeline into Unreal Engine would theoretically allow anyone to quickly bring in their work into Unreal Engine projects set up to run in the Data Arena and explore their work in 360º stereo with UE's incredibly lighting and material qualities.

A few weeks ago we started looking into the popular modelling software Rhino to figure out how best to export data. After trying a few common formats, we found FBX to play nicely with Unreal Engine and carry over material properties. Here's a simple red box coated with a glossy red "paint" in Rhino.

Unreal Engine screenshots

From here...

This first test came out pretty well with minimal issues and was a good first step towards developing some sort of pipeline. From here we wondered if it would be possible to specify a model to view at runtime, especially coming off the back of the previous experiment where we were changing lights through command line arguments.

Long story short we couldn't quite crack it. Unreal Engine doesn't display 3D models like FBX files, it imports and then interprets them into its own asset system of static meshes and materials. For us to be able to specify a model at runtime means we would need access to this importing and asset creation system at runtime which currently isn't possible (at least in 4.25). It might not be the safest path either, as the importing process handles a few options about the creation of materials and search for textures etc that you might not want to just automate at runtime.

As we move towards developing a pipeline, we're keeping in mind that it might look something closer to a template file that we provide to students or researchers working in these spaces, along with some instructions for importing and placement, and then take said file back to view in the Data Arena.

Here's our level blueprint. A custom function called Get Option Value has the task of taking in a specified argument name (e.g LightOneHue) and finding its value. The key node here is the first Get Command Line node which retrieves the entire command that was used to launch the project as a string. From there, after much splitting and searching, we return the value assigned to the argument.

From there, after the BeginPlay event, this is called and the integer is passed into a HSV to RGB node to generate a colour and applied to the geometry material and light colour of a point light actor. Currently this is repeated for each light but optimisation can come later!

From this little experiment we can see that it's absolutely possible to retrieve basic pieces of information at runtime (numbers and text). Next we'd like to explore the possibility of specifying a CSV file (for example), or a more complex dataset or 3D model at runtime.