While only peripherally related, Bill W's recent thread:

https://news.povray.org/povray.documentation.inbuilt/thread/%3Cweb.68573b7934ec28cb1f9dae3025979125%40news.povray.org%3E/

reminded me of longstanding plans for an inbuilt function called 
f_flat() or similar in yuqk.

Probably 10 years ago or so, I played with an image manipulation include 
called blobblur.inc. It used an arrangement of three blobs in what I 
called a 'blob-flat'. A blob-flat amounts to a central positive blob 
with two negative blobs offset linearly to either side. The two negative 
blobs flatten the central positive blob.

I had enough time this morning to play with mapping the technique to a 
handful of functions as a start on a generalized f_flat() inbuilt, 
support function. The gradients for the resulting iosurface function are 
 >1.0, but still quite good ( 1.45 ~sqrt(2) where the input function's 
gradients are 1.0 / linear).

Attached are two images and an example scene file for use with v3.8 beta 
2 - should anyone want to play with the method too. For one image, three 
f_sphere()s are used, and with the other, three of yuqk's inbuilt 
f_cone()s. The f_cone() function with basic arguments returns a double cone.

Aside: For isosurfaces the central function is negatively defined and 
the two others positively.

Bill P.

Post a reply to this message

Attachments:
Download 'blobflatlike00.png' (63 KB) Download 'blobflatlike03.png' (51 KB) Download 'tmp38.pov.txt' (3 KB)

Preview of image 'blobflatlike00.png'

Preview of image 'blobflatlike03.png'