[vtkusers] Re: Help me please I am pupil :)

[Goodwin Lawlor]

Jose David Pfuturi Huisa wrote:
> hello all. I am from Peru. I speak Spanish.
> I wanted to know as I can create own functions in vtk. That is to say, 
> that class receives the function. For example if I want to draw f=x*x+5 
> or others.
> cant i user VtkImplicitFunction????
> Where i write the function???
> thank you very much to all.

Hello there in Peru!

I think vtkQuadric (http://www.vtk.org/doc/release/5.0/html/a01940.html 
) will do what you want. A quadric is:

F(x,y,z) = a0*x^2 + a1*y^2 + a2*z^2 + a3*x*y + a4*y*z + a5*x*z + a6*x + 
a7*y + a8*z + a9

so for your expression, f = x*x + 5

you'd try:

quadric->SetCoefficients(1,0,0,0,0,0,0,0,0,5);

To visualize the function have a look at 
VTK/Examples/ImageProcessing/Tcl/Contours2D.tcl

hth,


Goodwin