troika VS nanovg

troika (specifically troika-three-text)

Text is relatively hard to render with WebGL and browsers have a limit, of usually 16 framebuffers that you can use for WebGL contexts. Our charts are written for a WebGL target so we don't want to use up that precious resource for text rendering. In our specific use case we usually have a large degree of control over the browser so we can configure it, but if the target is web we don't have that control. Grabbing a WebGL context also takes a significant period of time, usually a hundred milliseconds or more on my computer, and not displaying data in that time isn't a great user experience.

There's a great WebGL library for doing that on the web using any .ttf, .otf, or .woff font - https://github.com/protectwise/troika/tree/master/packages/t...

BGFX is a general-purpose 3D graphics engine, not a GUI nor vector graphics framework.

Nanovg is an awesome vector graphics library, but has limitations. (1) no ClearType, I fixed in my fork: https://github.com/Const-me/nanovg (2) The only way to get AA is hardware MSAA, unfortunately many popular platforms like Raspberry Pi don’t have good enough hardware to do it fast enough. Nanogui is built on top of Nanovg, shares the limitations.

I agree with the OP that Cairo and Skia are the only viable ones for Linux.

It’s sad because Windows has Direct2D for decades now (introduced in Vista), and unlike 2006, now in 2021 Linux actually has all the lower-level pieces to implement a comparable equivalent. Here’s a proof of concept: https://github.com/Const-me/Vrmac#vector-graphics-engine

> in your words, that "the quality is not good"

Oh, you were asking why I said so? Because I have clicked the “notes document” link in the article, the OP used the same tiger test image as me, and that document has a couple of screenshots. And these were the only screenshots I have found. Compare them to screenshots of the same vector image rendered by my library, and you’ll see why I noted about the quality.

> Vrmacs draws paths by decomposing them into triangles, rendering them with the GPU rasterizer, and antialiasing edges using screen-space derivatives in the fragment shader.

More or less, but (a) not always, thin lines are different. (b) that’s a high-level overview but there’re many important details on the lower levels. For instance, “screen-space derivatives of what?” is an interesting question, critically important for correct and uniform stroke widths. The meshes I’m building are rotation-agnostic, and to some extent (but not completely) they are resolution-agnostic too.

> and it is perfectly capable of rendering high-quality small text on the GPU

It is, but the performance overhead is massive, compared to GPU rasterizer rendering these triangles. For real-world vector graphics that doesn’t have too much stuff per pixel that complexity is not needed because triangle meshes are good enough already.

> it looks like it occupies a sweet spot similar to NanoVG

They’re similarities, I have copy-pasted a few text-related things from my fork of NanoVG: https://github.com/Const-me/nanovg/ However, Vrmac delivers much higher quality of 2D vector graphics (VAA, circular arcs, thin strokes, etc), is much faster (meshes are typically reused across frames), and is more compatible (GL support on Windows or OSX is not good, you want D3D or Metal respectively).