Change curve type from quadratic to cubic

[RandomMaerks]

At the moment, when a glyph has curves, they're quadratic Bézier curves.

It might be due to the fact that .ttf files of the original Atkinson Hyperlegible fonts were used to convert to .sfd files. TrueType fonts use quadratic curves.

Quadratic curves are usually fine, but they are a pain to edit. Unlike cubic Bézier curves where one curve has 2 end points and the control points are separated, quadratic curves have multiple "intermediate points" and 1 control point for every two consecutive points in order to compensate for that smoothness.
You can edit a cubic curve just by editing either the end points or the control points, but you'll have to edit a quadratic curve by either manually editing every single end points (which doesn't always turn out great), or by merging all the points and be left with a "set smoothness".

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So my idea is to a) change the curve type to cubic and b) manually edit each curve to be cubic. It sounds like a terrible idea, but it might save a lot of headaches in the future.

You can go to Element → Font Info → Layers, then in the Font Type section, click 'All layers cubic'.

Once you've done that, you can merge the 'intermediate points' and fix the control points by harmonising the curves.

curve.mp4

[RandomMaerks]

@jacobxperez If you approve of this idea, I can try to implement this alongside the Vietnamese language support thing

[jacobxperez]

@RandomMaerks Yes you are right I will start working on this implementation immediately, thanks for the awesome contribution you are bringing to this project.

[RandomMaerks]

Great! Also I will be implementing this for the Regular style since I'm also adding Vietnamese simultaneously. So if you don't mind, you can start with the other styles

[jacobxperez]

@RandomMaerks Alright thanks!!