The adventures of building a web renderer

The adventures of building a web renderer
This thread is for sharing my learnings and war stories from the LDraw web-rendering project buildinginstructions.js.
You can see how it evolves on

Here is a current example of how it renders a LEGO model:

[Image: 14.png]

It was not always like this. While there are at least two other web renderers that I know of, I still decided to start this project from scratch. This way I would get practical experience with the technologies involved (WebGL, Three.js, GLSL, etc.), and focus on having performance in mind from the very beginning. While the project itself hopefully ends up being of practical use for many, my goal with this thread is to share my experiences, wins and losses, and perhaps even get some good feedback to help drive the project forward.

The project started in July 2018 with the first breakthrough being in August 1. Back then I had finished an MPV of the .ldr parser while trying to adhere to the Three.js best practices for building a Loader. By modifying one of the Three.js sample files, I was able to get it to render:

[Image: p4xuzyP.png]

As you can see, there were some massive BFC issues, but that was alright for a start. The important part was to get started and get something, anything really, up and running.
My top 3 takeaways from this early stage are:

- Ignore everything that is not absolutely needed in order to get started. This includes conditional lines, quads, BFC, colors, metadata, viewport clipping, etc, etc. While it is important to do things right, the proof of concept both gave me something tangible and came with a morale boost.

- Three.js and the LDraw file format work well together from the perspective of placing things in 3D. It is obvious that James Jessiman knew what he was doing when designing the specification.

- Depending on your approach of design, BFC can be very difficult to get right. There is psudocode in the spec, but unfortunately it did not fit into the data models I had chosen. The pseudocode assumes a single pass of computing both BFC information and triangle wrapping, while my code handles the BFC computation in a separate initial step that creates reusable components.

That is all for the first post. I will try to keep this thread alive with more war stories.
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The adventures of building a web renderer - by Lasse Deleuran - 2018-11-05, 16:25

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