I have a problem in qpainterpaht calculation.

Here are the two QPainterPath:

The two path: subjectpath, clippath. One edge is overlapping in math, but maybe not in computer data

 the path data and the schematic diagram

Accordint to qpainterpath doc, the result of (subjectpath - clippath) should be subjectpath. But the result in my code is null.

Would someone give me some advise?

Thank you!

here is the code:
 
double dy_x = -0.8609277780573142;

double dy_y = -179.18974019701932;

double dx_x = -100.56567051873533;

double dx_y = 0.48317375299134985;

double p1_x = 174.49572649572647;

double p1_y = 239.04273504273505;

double p2_x = 297.57264957264954;

double p2_y = 238.4957264957265;

QPainterPath p1;

p1.moveTo(p1_x, p1_y);

p1.lineTo(p1_x - dy_x + dx_x, p1_y - dy_y + dx_y);

p1.lineTo(p2_x - dy_x - dx_x, p2_y - dy_y - dx_y);

p1.lineTo(p2_x, p2_y);

p1.lineTo(p1_x, p1_y);

QPainterPath p2;

p2.moveTo(p1_x, p1_y);

p2.lineTo(p1_x + dy_x + dx_x, p1_y + dy_y + dx_y);

p2.lineTo(p2_x + dy_x - dx_x, p2_y + dy_y - dx_y);

p2.lineTo(p2_x, p2_y);

p2.lineTo(p1_x, p1_y);

double r1_x = 201.2991452991453;double r1_y = 199.11111111111106;double r2_x = 225.36752136752136;double r2_y = 259.8290598290598;double r3_x = 248.3418803418803;double r3_y = 198.01709401709397;QPainterPath p3;

p3.moveTo(r1_x, r1_y);

p3.lineTo(r2_x, r2_y);

p3.lineTo(r3_x, r3_y);

p3.lineTo(r1_x, r1_y);

QPainterPath result = (p3 & p1) - p2;

if (result.isEmpty()) {

{{ qDebug()<<"Result is empty";}}

}

else {

{{ qDebug()<<"Result is not empty";}}

}

the code diagram, the result should be the orange part!

if r2_y = 252.8290598290598, the result should be right.