POV-Ray : Newsgroups : povray.general : rolled up maps : Re: rolled up maps Server Time
1 Aug 2024 08:22:54 EDT (-0400)
  Re: rolled up maps  
From: Mike Williams
Date: 16 Jan 2006 10:19:28
Message: <jcHroAAqi7yDFwTj@econym.demon.co.uk>
Wasn't it Trevor G Quayle who wrote:
>"Jim Holsenback" <jho### [at] hotmailcom> wrote:
>> as you can see from the attached image it wraps the image fine around the
>> rolled up ends but not on the flat part in the middle. scale, rotate, or
>> translate issues? maybe this isn't possible, but notice how the image is
>> wrapped on both sides of the object (front and back of the map object)
>>
>> Thanks!
>
>Your likely culprit here is that the size of the mesh in the flat area is
>larger than in the rolled areas, causing the uv mapping for those triangle
>sto be stretched.  Even though it is flat between the rolled ends, try to
>keep the mesh in this area approximately the same size as in the ends.

The problem actually is that the spline control points are no evenly
spaced. I used control points from 0.0 to 0.5 for the rolled area at one
end, and control points 0.5002 to 1.0 for the rolled area at the other
end. I hadn't realized that the uv mapping would follow the control
point spacing.

The whole thing would need to be redesigned to have control points that
are evenly distributed along the spline. It turns out to be quite tricky
to write it so that the spline is generated with evenly spaced control
points.

Is there a utility that will take a spline and reorganize the control
points to be evenly spread without changing the shape?

-- 
Mike Williams
Gentleman of Leisure


Post a reply to this message

Copyright 2003-2023 Persistence of Vision Raytracer Pty. Ltd.