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9 Aug 2024 19:40:35 EDT (-0400)
  mesh2 in csg (Message 1 to 6 of 6)  
From: ryan constantine
Subject: mesh2 in csg
Date: 6 May 2000 21:05:24
Message: <3914C1FF.C2D4FF45@yahoo.com>
what i want to do is intersect a mesh2 object with a box (hoping it will
make a solid).  is it possible?  i'm using megapov 0.4, but i still get
an error telling me "patch objects not allowed in intersection".  it
does look right, but when i cut a piece out to see if it is solid, a
hole in the surface is cut, and the inside is the color of the
background.  does that mean that only the outer surface of a mesh2
object is visible?  TIA


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From: Nathan Kopp
Subject: Re: mesh2 in csg
Date: 7 May 2000 14:32:59
Message: <3915b6db@news.povray.org>
Try adding something like this to your mesh object:
inside_vector <0, 0, 1>

In MegaPov, this will instruct MegaPov to treat this as a solid mesh.  Be
aware that the algorithm that computes mesh insidedness is flawed, but it
does work most of the time.  Read the docs (section 5.3) for more
information.

-Nathan

ryan constantine <rco### [at] yahoocom> wrote...
> what i want to do is intersect a mesh2 object with a box (hoping it will
> make a solid).  is it possible?  i'm using megapov 0.4, but i still get
> an error telling me "patch objects not allowed in intersection".  it
> does look right, but when i cut a piece out to see if it is solid, a
> hole in the surface is cut, and the inside is the color of the
> background.  does that mean that only the outer surface of a mesh2
> object is visible?  TIA


Post a reply to this message

From: ryan constantine
Subject: Re: mesh2 in csg
Date: 7 May 2000 16:03:00
Message: <3915CCA3.6E85D2C7@yahoo.com>
perfect!  thanks!

Nathan Kopp wrote:
> 
> Try adding something like this to your mesh object:
> inside_vector <0, 0, 1>
> 
> In MegaPov, this will instruct MegaPov to treat this as a solid mesh.  Be
> aware that the algorithm that computes mesh insidedness is flawed, but it
> does work most of the time.  Read the docs (section 5.3) for more
> information.
> 
> -Nathan
> 
> ryan constantine <rco### [at] yahoocom> wrote...
> > what i want to do is intersect a mesh2 object with a box (hoping it will
> > make a solid).  is it possible?  i'm using megapov 0.4, but i still get
> > an error telling me "patch objects not allowed in intersection".  it
> > does look right, but when i cut a piece out to see if it is solid, a
> > hole in the surface is cut, and the inside is the color of the
> > background.  does that mean that only the outer surface of a mesh2
> > object is visible?  TIA


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From: ryan constantine
Subject: Re: mesh2 in csg
Date: 7 May 2000 16:15:55
Message: <3915CFAB.B8D2FC52@yahoo.com>
one problem.  hopefully there is a solution.  the mesh came out solid
just perfect, but there are artifacts of the cube i cut the mesh out of
under my object.  does this indicate holes in my mesh?  i can't see
any.  or does it mean that i have some normals flipped around?  the
artifacts are what's left if you take an inverse shadow projected
directly below the object onto a plane.  if you need a pic, i can post
one in the images group.  thanks again.

Nathan Kopp wrote:
> 
> Try adding something like this to your mesh object:
> inside_vector <0, 0, 1>
> 
> In MegaPov, this will instruct MegaPov to treat this as a solid mesh.  Be
> aware that the algorithm that computes mesh insidedness is flawed, but it
> does work most of the time.  Read the docs (section 5.3) for more
> information.
> 
> -Nathan
> 
> ryan constantine <rco### [at] yahoocom> wrote...
> > what i want to do is intersect a mesh2 object with a box (hoping it will
> > make a solid).  is it possible?  i'm using megapov 0.4, but i still get
> > an error telling me "patch objects not allowed in intersection".  it
> > does look right, but when i cut a piece out to see if it is solid, a
> > hole in the surface is cut, and the inside is the color of the
> > background.  does that mean that only the outer surface of a mesh2
> > object is visible?  TIA


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From: Nathan Kopp
Subject: Re: mesh2 in csg
Date: 8 May 2000 00:35:07
Message: <391643fb@news.povray.org>
First, try using a different inside_vector (try a few).  If that doesn't
solve the problem, a pic would help.

-Nathan

ryan constantine <rco### [at] yahoocom> wrote...
> one problem.  hopefully there is a solution.  the mesh came out solid
> just perfect, but there are artifacts of the cube i cut the mesh out of
> under my object.  does this indicate holes in my mesh?  i can't see
> any.  or does it mean that i have some normals flipped around?  the
> artifacts are what's left if you take an inverse shadow projected
> directly below the object onto a plane.  if you need a pic, i can post
> one in the images group.  thanks again.


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From: ryan constantine
Subject: Re: mesh2 in csg
Date: 8 May 2000 12:26:14
Message: <3916EB5D.569BBED1@yahoo.com>
thanks for your help.  i'm an idiot.  i've read the docs so many times
that i don't see everything that's there, if you know what i mean.  i
didn't realize that a solid mesh is actually an object.  i had focused
on the 'mesh can be used in csg' part only. so now that the mesh is a
solid object, it looks great!  now if i can just figure out all of the
export settings for 3dwin.  i made the mesh using spatch and exporting
as dxf.  then in 3ds i made sure the normals were all facing out of the
object, but didn't change anything else (i want this to be as much a pov
only model as i can).  in 3ds, my compound curves are perfectly smooth. 
when i export as a 3ds and then use 3dwin to convert to moray, i can't
seem to get the same level of smoothness.  likewise with 3ds2pov which i
believe you helped develop.  any tips for getting a mesh or mesh2
(depending i guess on which converter i use) to look exactly like the
3ds file?  thanks again.

Nathan Kopp wrote:
> 
> First, try using a different inside_vector (try a few).  If that doesn't
> solve the problem, a pic would help.
> 
> -Nathan
> 
> ryan constantine <rco### [at] yahoocom> wrote...
> > one problem.  hopefully there is a solution.  the mesh came out solid
> > just perfect, but there are artifacts of the cube i cut the mesh out of
> > under my object.  does this indicate holes in my mesh?  i can't see
> > any.  or does it mean that i have some normals flipped around?  the
> > artifacts are what's left if you take an inverse shadow projected
> > directly below the object onto a plane.  if you need a pic, i can post
> > one in the images group.  thanks again.


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