"Kenneth" <kdw### [at] gmailcom> wrote:

>
> Unlike a regular height_field, the image_map eats INTO the cylinder (but with
> the correct 'positive' grayscale height values.) For example, if your image_map
> has white values that are 1.0 in brightness, that part of the corresponding
> cylindrical heightfield will by at the outer radius of the cylinder surface;
> darker image colors will eat *into* the cylinder.
>

Actually, that's only half-true (which has just become clear to me-- and I've
been working with the HF_Cylinder macro for years!)

As the 'depth' value in the macro increases, the radius of the entire
height_field cylinder ALSO increases (but not the *length* of the cylinder)--
you end up with a 'fatter' cylinder, which actually distorts the 3D image_map
pattern. The pattern looks stretched-out horizontally. (You can see this by
setting 'depth' to an extreme .99.)

IDEALLY, as 'depth' increases, the cylinder should stay at the same radius, with
the image_map function simply 'eating into' it. But that's not what happens.

I'm working on some SCALE equations to compensate for this, but it's...
complicated. The first thing to do is to scale up the *length* of the cylinder,
to get the embossed pattern to look undistorted again. Then the entire cylinder
needs to be scaled *down*, to get it back to its original radius and length.

The tricky thing about this is that it all depends on the particular 'depth'
value used.

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