Mathieu,
Yes, you are right. Thanks for reporting this bug.
Will be fixed in next release.
Rene Brun
Mathieu de Naurois wrote:
>
> Hello Rooters,
>
> If you create a Arc with:
>
> TArc *Arc = new TArc (0,0,1,90,180);
> Arc->Draw();
>
> you should obtain a quarter of circle in the upper-left corner of the
> picture, but you obtain it on the upper-RIGHT corner.
>
> It seems to me that this bug is in the function TEllipse::PaintEllipse:
>
> the rotation angle theta is taken into account, but not the first angle
> phimin:
>
> void TEllipse::PaintEllipse(Float_t, Float_t, Float_t, Float_t, Float_t
> phimin,Float_t phimax, Float_t theta)
> {
> //*-*-*-*-*-*-*-*-*-*-*Draw this ellipse with new
> coordinates*-*-*-*-*-*-*-*-*
> //*-* ======================================
>
> const Int_t np = 40;
> const Float_t PI = 3.141592;
> static Float_t x[np+2], y[np+2];
> TAttLine::Modify(); //Change line attributes only if necessary
> TAttFill::Modify(); //Change fill attributes only if necessary
>
> Float_t angle,dx,dy;
> Float_t dphi = (phimax-phimin)*PI/(180*np);
> Float_t ct = TMath::Cos(PI*theta/180);
> Float_t st = TMath::Sin(PI*theta/180);
> for (Int_t i=0;i<np;i++) {
> angle = Float_t(i)*dphi;
>
> ---------> I think, one must add 'phimin' to this 'angle'!
>
> dx = fR1*TMath::Cos(angle);
> dy = fR2*TMath::Sin(angle);
> x[i] = fX1 + dx*ct - dy*st;
> y[i] = fY1 + dx*st + dy*ct;
> }
> if (phimax-phimin >= 360 ) {
> x[np] = x[0];
> y[np] = y[0];
> if (GetFillColor()) gPad->PaintFillArea(np,x,y);
> if (GetLineStyle()) gPad->PaintPolyLine(np+1,x,y);
> } else {
> x[np] = fX1;
> y[np] = fY1;
> x[np+1] = x[0];
> y[np+1] = y[0];
> if (GetFillColor()) gPad->PaintFillArea(np+1,x,y);
> if (GetLineStyle()) gPad->PaintPolyLine(np+2,x,y);
> }
> }
>
> --------------------------------------------
>
> A suggestion: Would it be possible to provide an option to draw only the
> contour of the ellipse, without the lines joining the center?
>
> Thank you
> --------------------------------------------
>
> Mathieu de Naurois
> LPNHE Ecole Polytechnique
> denauroi@polhp1.inp3.fr
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