Re: [Dev-C++] marching cubes (3D)

[michele <mic...@li...>]

Hi Jan (thank you and thank you Per)...
>>>The testing if the point is inside would be pretty simple. I expect =
you have some equations that define the conditions. Then setting each =
point of 3D grid into=20
>>>this equations would do the work. Then if all the quations are valid, =
then the point is inside.

Yes it's exactly what I have done.. and really isn't difficut, the real =
question is how to render that volume ( now I have a pretty =
rapresentation (but 'discontinuous')... I draw a little cube in =
corrispondence of every point inside the surface).


But I have found... Another good article (by Paul Bourke) with c code =
(OpenGL):
http://astronomy.swin.edu.au/~pbourke/modelling/polygonise/
I think this will be very helpful (for me and for all interested) and so =
I signalize you.=20
Bye



  ----- Original Message -----=20
  From: Jan Ringos=20
  To: michele=20
  Sent: Wednesday, April 14, 2004 6:36 PM
  Subject: Re: [Dev-C++] marching cubes (3D)


  Hello Michele.
  Yes I am interested but I am not sure if I can help you.
  I read the articles but I can't imagine how to find the border points.

  The testing if the point is inside would be pretty simple. I expect =
you have some equations that define the conditions. Then setting each =
point of 3D grid into this equations would do the work. Then if all the =
quations are valid, then the point is inside.

  Hope it helps...
  ---
  Jan Ringos, Tr...@mx...
  http://Tringi.Mx-3.cz

    ----- Original Message -----=20
    From: michele=20
    To: Jan Ringos=20
    Sent: Wednesday, April 14, 2004 3:23 PM
    Subject: Re: [Dev-C++] marching cubes (3D)


    hi Jan,
    if you are interested...
    What I have to do is to render a 3D volume from sampled points =
(certain conditions define that volume)...

    So what I do is to divide the 3D space in a 3D grid and to test each =
point of this grid to know if it is inside or outside my suface...
    Regards=20
    (if you have some suggestions let me know!  thanks)



    ----- Original Message -----=20
      From: Jan Ringos=20
      To: michele=20
      Sent: Friday, April 09, 2004 6:44 PM
      Subject: Re: [Dev-C++] marching cubes (3D)


      Very interesting. But honestly I see no use for it. In game I =
would instead use something like height-map or model with clipping =
definitons.
      But I don't know what specific are you want to do with it. Anyway =
It shouldn't be too difficult to implement exact use.

      ---
      Jan Ringos, Tr...@mx...
      http://Tringi.Mx-3.cz

        ----- Original Message -----=20
        From: michele=20
        To: Jan Ringos ; DEV-C++=20
        Sent: Friday, April 09, 2004 10:18 AM
        Subject: Re: [Dev-C++] marching cubes (3D)


        Hi...
        =20
        "The marching cubes algorithm is used in volume rendering to =
construct an isosurface from a 3D field of values.
        The 2D analog would be to take an image, and for each pixel, set =
it to black if the value is below some threshold, and set it to white if =
it's above the threshold. Then smooth the jagged black outlines by =
skinning them with lines..." [James Sharman]

        if you (and someone else) want to read some interesting articles =
about marching cubes:
        Introduction:
        http://www.exaflop.org/docs/marchcubes/ind.html
        =20
        Article with some c code:=20
        =
http://www.cfxweb.net/modules.php?name=3DNews&file=3Darticle&sid=3D199
        (more available at =
http://matrix.netsoc.tcd.ie/~nash/metaballs/src/ gently by Nicholas: =
nn...@st...)