On 9/8/19 11:11 PM, Kima wrote:
> I wonder if there is a way to create a curved prim (not the edges, but its
> surface).
> 
> Since prism already has an option of conic_sweep, the same principle may create
> a curvature on its surface.
> 
> In conic_sweep, the size of prism decreases linearly in the y-axis. Instead of a
> linear decrease, can we shrink the prism along the y-axis to form a semi-sphere
> instead of a sharp cone (of conic_sweep)?
> 
Nothing inbuilt(1,2).

Various partial methods have been created over the years to represent 
rounded prisms. Using the POV-Ray site search turns up:

http://news.povray.org/povray.binaries.images/thread/%3C3bd3afc7%241%40news.povray.org%3E/

for example.

I've played with isosurface, df3 based, sampling methods some of which 
can be found at:

  http://wiki.povray.org/content/User:Wfpokorny/DensityFile

and if you search of soft_object you'll turn up a method doing the 
sampling and df3 grid representation of the fly internally. Rounded 
sides and flat top/bottom opens up other partial solutions.

Sometimes folks model for rounded text in some other tool and export the 
mesh for use in POV-Ray. Tri/Quad patch mesh modeling with smoothing 
normals is itself a partial solution with trade offs though it's the one 
most supported out and about 3D graphics wise.

Bill P.

(1) - Not easy to do generically & on the fly at good performance. My 
personal thinking is with POV-Ray  it would be a 'better' direction to 
add some sort of any object to point cloud/mesh then mesh smoothing for 
such rounding / blobbing ability. Something done this way would be 
applicable to all objects and move us closer to mesh export-ability. 
Here too there have been a number of external tools/attempts over the 
years, but nothing has become 'the' method that I see. I have my own 
idea for a surface, random / curvature driven walk, approach I think 
might be better for maintaining hard / un-smoothed edges in the 
generated meshes that I've never gotten around to trying. (Aside: There 
is an ability to flip the normal directions via 2d point list direction 
- and so surface top/bottom/side textures - that exists with prism and 
lathe points lists which doesn't map to meshes.)

(2) - The current conic sweep is toward the x,z origin not some local 
'medial axis' inside the shape.

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