ROOT   Reference Guide
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,...
Definition: TGLParametric.h:35
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
double Pi()
Mathematical constants.
Definition: Math.h:88
TMath.
Definition: TMathBase.h:35
Double_t Cos(Double_t)
Definition: TMath.h:643
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.