William F Pokorny <ano### [at] anonymousorg> wrote:

> The top row comes from today's v3.8 beta 2, where the right column added
> '+mv3.8' to fix a v3.8 defaulting issue (see below).

So, your ellipsoid there reminded me:

Philip Laven pointed out that due to the conditions that give rise to the glory
effect, the rainbow is virtually never circular.
I tried scaling the rainbow {} "object" but as I expected, that didn't work.

I had to scale the camera, which means that to do it properly / realistically,
then everything in the scene needs to be enclosed in a union {}, the camera
scaled, and the union scaled with the inverse of the camera transform.

Currently, we can scale and otherwise transform the pigment of a sky_sphere:
https://wiki.povray.org/content/Reference:Sky_Sphere

It's unclear if something can be done with how the rainbow {} effect gets
implemented.

I'm unsure if any other sorts of optical effects are direction-vector
controlled, (aoi? slope?) but allowing transforms on rainbow {} (and maybe even
sky_sphere) might be interesting for future optical projects or artistic effects
that are difficult or impossible to achieve otherwise.

- BW

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