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glparametrics2.C File Reference

## Detailed Description

Show rendering of parametric surfaces.

A parametric surface is defined by three functions: S(u, v) : {x(u, v), y(u, v), z(u, v)}. To create parametric surface and draw it one has to:

1. Create canvas, which support OpenGL drawing (two ways):
• Call gStyle->SetCanvasPreferGL(kTRUE)
• Or create canvas with name, wich contains "gl".
2. create TGLParametricEquation object.
"some FORMULA here - x(u, v)",
"some FORMULA here - y(u, v)",
"some FORMULA here - z(u, v)",
uMin, uMax, vMin, vMax);
A parametric surface is a surface defined by a parametric equation, involving two parameters (u,...
where FORMULA is the same string (mathematical expression), as in TF2, but you should use 'u' (or 'U') instead of 'x' and 'v' (or 'V') instead of 'y'.
3. Call equation->Draw(); Parametric surfaces support 21 color "schemes", you can change the color:
• place mouse cursor above surface (surface is selected in pad)
• press 's' or 'S'. void klein_bottle(TGLVertex3 &dst, Double_t u, Double_t v)
{
using namespace TMath;
const Double_t r = 4. * (1. - Cos(u) / 2.);
if (u < Pi()) {
dst.X() = 6 * Cos(u) * (1. + Sin(u)) + r * Cos(u) * Cos(v);
dst.Y() = 16 * Sin(u) + r * Sin(u) * Cos(v);
} else {
dst.X() = 6 * Cos(u) * (1. + Sin(u)) + r * Cos(v + Pi());
dst.Y() = 16 * Sin(u);
}
dst.Z() = r * Sin(v);
}
void glparametrics2()
{
TCanvas *c = new TCanvas("canvas","Parametric surfaces with gl", 100, 10, 700, 700);
c->Divide(2, 2);
c->cd(1);
"1.2 ^ v * sin(u) ^ 2 * sin(v)",
"1.2 ^ v * sin(u) * cos(u)",
"1.2 ^ v * sin(u) ^ 2 * cos(v)",
0., TMath::Pi(), // 0 <= u <= pi
-TMath::Pi() / 4., 5 * TMath::Pi() / 2.); // -pi/4 <= v <= 5*pi/2
p1->Draw("");
c->cd(2);
TGLParametricEquation *p2 = new TGLParametricEquation("Limpet torus",
"cos(u) / (sqrt(2) + sin(v))",
"sin(u) / (sqrt(2) + sin(v))",
"1. / (sqrt(2) + cos(v))",
p2->Draw();
c->cd(3);
TGLParametricEquation *p3 = new TGLParametricEquation("Klein bottle",
klein_bottle,
0., TMath::TwoPi(),
0., TMath::TwoPi());
p3->Draw();
c->cd(4);
"v * cos(u)",
"v * sin(u)",
"u",
-3., 3.,
-3., 3.);
p4->Draw();
}
ROOT::R::TRInterface & r
Definition Object.C:4
#define c(i)
Definition RSha256.hxx:101
double Double_t
Definition RtypesCore.h:59
const Bool_t kTRUE
Definition RtypesCore.h:91
R__EXTERN TStyle * gStyle
Definition TStyle.h:412
The Canvas class.
Definition TCanvas.h:23
3 component (x/y/z) vertex class.
Definition TGLUtil.h:84
Double_t X() const
Definition TGLUtil.h:119
Double_t Z() const
Definition TGLUtil.h:123
Double_t Y() const
Definition TGLUtil.h:121
virtual void Draw(Option_t *option="")
Default Draw method for all objects.
Definition TObject.cxx:197
void SetCanvasPreferGL(Bool_t prefer=kTRUE)
Definition TStyle.h:325
TMath.
Definition TMathBase.h:35
constexpr Double_t Pi()
Definition TMath.h:37
Double_t Sin(Double_t)
Definition TMath.h:639
constexpr Double_t TwoPi()
Definition TMath.h:44

Definition in file glparametrics2.C.