"Thorsten Froehlich" wrote:
> But there is no "internal coordinate system"!
> The coordinate system used in images is extremely
> important as otherwise images could have a random
> orientation.

Agreed, coordinates are important. However, when working with images, users
expect up to be up and down to be down. They don't think that (0,0) must
always be (0,0) and (1,1) must always be (1,1) regardless of the coordinate
system used.

> One simply cannot use images without defining their
> origin and coordinate system.

Agreed.

> As soon as you edit the image you are going to
> expose the origin as well as the coordinate system
> to the user.

Depends on your definition of "exposing". Though many graphics programs show
the coordinates while editing, it's perfectly possible to draw an image
without thinking about the coordinates.

> Without doing so editing images would not be possible.

See above.

> In conclusion the origin as well as the coordinate system
> are well defined in POV-Ray and function images use this
> well defined coordinate system.

Images use one coordinate system while POV-Ray space use another coordinate
system. POV-Ray compensates for this, so that up remains up and down remains
down. But functions do not use a different coordinate system, and thus no
compensation should be done. In functions, when considering the square from
(0,0) to (1,1), it is the lower left corner that is the origin. Thus no
compensation should be done. Applying the compensation anyway only reverses
the image so that it's upside down.

> Sure, this cannot fit all needs, but changing this simple
> and obvious origin and coordinate system to some completely
> randomly choosing different origin and coordinate system
> just to make it work in this one special buggy scene file is
> simply unreasonable.

We're not discussing a random chosen origin and coordinate system. We're
discussing making sure that the alignment is correct regardless of the
origin and coordinate system used. I.e. making sure that upper right remains
upper right, lower left remains lower left etc. This is completely
consistent and reasonable and even intuitive too.

> If you find it reasonable, fine, but I don't and given
> my clear and simple reasoning I am not going to change
> my mind.

I find my reasoning clear and reasonable too and would like to continue to
discuss this matter.

> So we will continue to disagree
> on this and any further discussion will lead nowhere.

You haven't argued why POV-Ray should compensate in this case where
compensation is incorrect. All you have said is something like "compensation
is done for all image types and therefore it is correct". That isn't an
argument.

Rune
--
3D images and anims, include files, tutorials and more:
Rune's World:  http://rsj.mobilixnet.dk (updated Mar 19)
POV-Ray Users: http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Ring:  http://webring.povray.co.uk

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