Solid line turns into dashed (AA disabled, 1px width)

[Aleksevs]

Hello!

Tried to draw 1px polyline without antialiasing but bumped into a strange behaviour. Lines drawn almost vertically became dashed (see left pic).

Drawing sequence is like following (paint method in modified HelloWidget example):

p->setLineWidth(1);
p->setPixelAlign(QNanoPainter::PIXEL_ALIGN_NONE); // (Doesn't affect anything)
p->beginPath();

p->moveTo(200+0.25, 392); // (Fraction added to make assymetry)
p->lineTo(200+0.25 + 4, 0);
//p->moveTo(200+0.25 + 4, 0); // (*) Removes dashing
p->lineTo(200+0.25 + 8, 392);

p->setStrokeStyle("#202020");
p->stroke();

At the same time, after (*) line is uncommented, the plot gets much better (right pic).
Could you please give a clue how to fix this issue without adding moveTo for each line?

PS. Qt 5.15. Debug output during start:

Creating suitable QNanoBackend for OpenGL 4.6 context
Using backend: "OpenGL 3"

Regards,
Alekseus