Character path missing commands at smaller sizes

[gingerchris]

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Using the latest master branch, I'm seeing an issue where a path command is being dropped when rendering a certain character. If I increase the font size, the issue is not present, which makes me suspect there's some kind of rounding going on that causes this issue.

I've created a reproduction here comparing the current NPM release of opentype.js with a current build from the main branch.

Rendering this S character from Bodoni font at size 72 - all is good.

At size 53 it seems to be missing the final command and is drawing a diagonal line to close the path instead of a vertical one

[gingerchris]

Also noticed that trying a much smaller size (in this case 3) it's completely wrong

[Connum]

Can you please check the console to see if there appear any errors?

[gingerchris]

I see errors related to the platform (stackblitz) but after it's loaded I can clear the console, reload the preview and no errors come up. I have also validated this behaviour in nodejs and produced the same result

[Cadillac1010]

[herrstrietzel]

Opentype v2.0 post-optimization seems to have flaws.

Explicit optimization options should fix the problem

  const d = path.toPathData({
    optimize: false,
    decimalPlaces: 3,
    flipY: false,
  });

My assumption: the optimization checks for coinciding control point coordinates after rounding – for smaller font-sizes this will result in more commands being dropped.

Ideally the flipY default should be changed to false or the y-axis flipping shouldn't happen before (in the command parsing)

However, the above options won't be compatible with V1.3 API. I you can do without variable font support you should probably stick with v1.3.4