nanovg VS nanovg

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).

I use nanovg for my projects and it works surprisingly well for its size. It integration is pretty simple .... if you know a little bit of OpenGL, otherwise there is a slight learning curve.

The "engine" is built on top of amazing https://www.lwjgl.org/ and https://github.com/bkaradzic/bgfx/, and UI system is baked by https://github.com/memononen/nanovg and https://github.com/facebook/yoga

It's a library for drawing vector shapes, sort of like SVG - https://github.com/memononen/nanovg The old way in the SDK was with GDI+, but the benefit of a vector format is scalability to higher resolutions and better GPU usage. The workaround potentially costs some frames, but its better than bust panels for now.

If you are a beginner in computer graphics, I strongly suggest you to look at the nanovg library: it contains all the primitives you might want to render (circles, lines, filled polygons, text, images, ...). Integrating it in existing codebase is not that hard, since the library is rather small.

NanoVG is the closest thing I came across when I had a similar quesiton: https://github.com/memononen/NanoVG

unfortunately it doesn't seem like it's getting steady updates now unlike the last time I checked. But I imagine it's pretty mature at this point. There also seem to be ports in Metal/DX11 if you didn't want to be stuck in OpenGL.

Also there's NanoVG if you really want a vector api in C, but don't need anti-aliased clipping.

Getting sufficient antialiasing quality for 2D graphics is difficult on GPUs. https://github.com/memononen/nanovg accomplishes this with GL2/GLES2 level hardware for most of the stuff one would want to render as part of a GUI. My project https://github.com/styluslabs/nanovgXC supports rendering arbitrary paths with exact coverage antialiasing, but requires GLES3.1 or GL4 level hardware for reasonable performance.

> to learn the 'nuts and bolts' of rendering

These nuts and bolts are very different between CPU and GPU. CPU-based libraries are painting pixels in bitmaps in system memory. Most GPU-based libraries are uploading indexed triangle meshes, and rendering them with weird shaders.

Worse, there're no good open source implementations of GPU-based ones. Microsoft ships an implementation as a part of OS (Direct2D) but it's not open source. Linux simply doesn't have an equivalent.

At least for initial versions, consider C interop with this https://github.com/memononen/nanovg It cuts a few corners (no cleartype for text, CPU overhead for repeated rendering of same static paths) but it's still good overall, simple, and easy to use.

> My only concern with C# is the cross compatibility

Works well on Linux, Windows and OSX, including ARM CPUs. Not sure about Android and iOS, never tested.

My largest concern with C# would be performance. Technically the language allows to code in any style, but most guides and examples are using OO-heavy one.