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Transform trigonometric formulas to minimize the loss of precision

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Closes #18142.
This commit is contained in:
Artur Wieczorek
2018-06-23 20:45:49 +02:00
parent 9daf5bec98
commit fe6ebc528d
1 changed files with 3 additions and 3 deletions
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6
src/common/graphcmn.cpp
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@@ -486,9 +486,9 @@ void wxGraphicsPathData::AddArcToPoint( wxDouble x1, wxDouble y1 , wxDouble x2,
// Determine spatial relation between the vectors.
bool drawClockwiseArc = v1.GetCrossProduct(v2) < 0;
alpha = wxDegToRad(alpha) / 2.0;
wxDouble distT = r / sin(alpha) * cos(alpha);
wxDouble distC = r / sin(alpha);
alpha = wxDegToRad(alpha);
wxDouble distT = r / (1.0 + cos(alpha)) * sin(alpha); // = r / tan(a/2) = r / sin(a/2) * cos(a/2)
wxDouble distC = r / sin(alpha / 2.0);
wxASSERT_MSG( distT <= v1Length && distT <= v2Length,
wxS("Radius is too big to fit the arc to given points") );
// Calculate tangential points