> Alain<aze### [at] qwertyorg>  wrote:

>>> Hi there, I'd like to know if there is any way to extrude a mesh like this :
>>>
>>> mesh {
>>> triangle {<1,13.2146,-23.2146>,<3,14.286,-24.286>,<17,14.286,-24.286>   }
>>> triangle {<17,14.286,-24.286>,<19,13.2146,-23.2146>,<1,13.2146,-23.2146>   }
>>> triangle {<19,13.2146,-23.2146>,<17,14.286,-24.286>,<17,18.2146,-28.2146>   }
>>> triangle {<17,18.2146,-28.2146>,<19,19.2861,-29.2861>,<19,13.2146,-23.2146>   }
>>> triangle {<19,19.2861,-29.2861>,<17,18.2146,-28.2146>,<3,18.2146,-28.2146>   }
>>> triangle {<3,18.2146,-28.2146>,<1,19.2861,-29.2861>,<19,19.2861,-29.2861>   }
>>> triangle {<1,19.2861,-29.2861>,<3,18.2146,-28.2146>,<3,14.286,-24.286>   }
>>> triangle {<3,14.286,-24.286>,<1,13.2146,-23.2146>,<1,19.2861,-29.2861>   }
>>> triangle {<3,15.7146,-25.7146>,<17,15.7146,-25.7146>,<17,16.786,-26.786>   }
>>> triangle {<17,16.786,-26.786>,<3,16.786,-26.786>,<3,15.7146,-25.7146>   }
>>> triangle {<5,14.286,-24.286>,<7,14.286,-24.286>,<7,18.2146,-28.2146>   }
>>> triangle {<7,18.2146,-28.2146>,<5,18.2146,-28.2146>,<5,14.286,-24.286>   }
>>> triangle {<9,14.286,-24.286>,<11,14.286,-24.286>,<11,18.2146,-28.2146>   }
>>> triangle {<11,18.2146,-28.2146>,<9,18.2146,-28.2146>,<9,14.286,-24.286>   }
>>> triangle {<13,14.286,-24.286>,<15,14.286,-24.286>,<15,18.2146,-28.2146>   }
>>> triangle {<15,18.2146,-28.2146>,<13,18.2146,-28.2146>,<13,14.286,-24.286>   }
>>> }
>>>
>>> I'd like to extrude it following the y axis.
>>>
>>> I know I can do it using the "prism" fonction by keeping only the triangles
>>> points without the y coordinate, but it's kinda boring to do it manually.
>>>
>>> Maybe there is a solution to extrude every kind of 2D or 3D objects along an
>>> axis !?
>>>
>>>
>>> Thanks in advance for your reply.
>>>
>>>
>>
>> There is no surefire way to do that.
>> You can:
>> scale the mesh by a very large value along the Y axis and take the
>> intersection with a box of the desired thickness.
>> intersection{
>>   object{Your_mesh scale<1, 1e6,1>}
>>   box{<1,1,-30><19,-1,-20>}
>> }
>>
>> Extract the outermost points and use them to define a prism.
>>
>> Use an external programm to create a pre-extruded prism.
>>
>>
>>
>>
>> Alain
>
> Thanks for your reply but I'm afraid these ways to do it won't be ok for me.
>
> To extract the outermost points will request any kind of programm to do it, then
> I can't and I don't want to use an external programm.
>
> I've tried the first solution, I see what you meant by scaling it along the y
> axis, but the example I gave is a inclined plane surface made of triangles, so
> scaling it along y only creates another plane surface.
>
> Let's say there is only one triangle in my mesh, like that :
>
> mesh {
>              triangle {<0,0,0>,<1,0,1>,<1,1,0>}
> }
>
> How can I extrude it using only the 3 dimensions coordinates of the 3 points of
> the triangle. Of course I would like something quick and easy to do because I
> have to extrude more complex mesh (like the one on my first post)
>
>
>
>
>

Sory, but there is no easy solution.

You can make your mesh solid by adding an inside_vector, BUT, the 
resulting solid mesh don't have any side. You can intersect it from a 
box that is very slightly smaller than the mesh. It ONLY works IF the 
mesh is square.
Whener you don't see the side of the box, there sill be no side. Any 
opening will also be invisible.

If the mesh is some arbitrary non-square shape, you'll only get the top 
and bottom faces.

Also, whenever you have an even number of coplanar triangles you get an 
opening.

Another solution would be to have the mesh in a text file, read that 
file in a loop and construct your prism definition from that.

Then, if you want the top and bottom to follow the vertical shape of the 
mesh, you'll need to cut away the prism with the mesh itself using 
intersection for the top and difference for the bottom. Here again, you 
need a mesh made solid using inside_vector y.

Not realy easy, but you can automate the process, so you only need to 
code it once.




Alain

Post a reply to this message