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6 Nov 2024 16:30:14 EST (-0500)
  Questions! (Message 1 to 2 of 2)  
From: Saif Ansari
Subject: Questions!
Date: 31 Mar 1998 15:22:35
Message: <3521508B.4073@frontiernet.net>
Does anyone have any idea how to handle the point placement for the
cubic splines? I'm trying to create a few nicely curving shapes but have
found the "point-placing-by-eye" rather frustrating.

Oh, and incidentally (since both questions pertain to the same object)
is it possible to kind of "paste" a pre-existing image (a GIF or JPEG)
onto an object like a sphere or a box?

Lastly, is it possible to use a heightfield as a Normal/Texture/whatever
for an object? I'm thinking about cavewalls/stalactites, but more
specifically, instances when it will have to be "wrapped" around the
whole object like in coralreefs or stones.

I apologize if these are answered in the DOCs (I went through them, but
couldn't find specific answerse) or have been dealt with before. But any
leads on how to deal with them will help me greatly.

Thank you,
Saif.


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From: Johannes Hubert
Subject: Re: Questions!
Date: 1 Apr 1998 05:47:45
Message: <35221B51.B87A05AA@penttech.com>
Saif Ansari wrote:

> Oh, and incidentally (since both questions pertain to the same object)
> is it possible to kind of "paste" a pre-existing image (a GIF or JPEG)
> onto an object like a sphere or a box?

Is the "image_map" what you want? (POV-Docs: 7.6.1.5). Or did I understand
you wrong?

> Lastly, is it possible to use a heightfield as a Normal/Texture/whatever
> for an object? I'm thinking about cavewalls/stalactites, but more
> specifically, instances when it will have to be "wrapped" around the
> whole object like in coralreefs or stones.

You can use any bitmap (and a heightfield is basically a bitmap) as a
texture (image_map) or normal-modifier (bump_map, Docs: 7.6.2.3). The
problem: When you use a bitmap in this way, you only change the colors
(image_map) or normals (bump_map) of the object, not the shape of an object
(That is, the outline of a heavily bump-mapped object is still plain, making
it look very strange when viewed fromt he side). Changing the actual shape
of an object is very hard (if not close to impossible) in POV-Ray.
Displacement maps are the general solution for that in raytracing, but
POV-Ray doesn't have that feature. Mapping a heighfield to an object would
also be a solution, but is not possible (heightfields are always planar in
POV-Ray). But some of the heightfield tools (HF-Lab/GForge?) can map a
heightfield to some other shape (a sphere for example) and output a
triangle-mesh for use with POV-Ray.

I hope this helps a bit,
Johannes.


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