V-up texture coordinate support

[Chien Yang]

Hi all,

      Java images are defined such that (0, 0) references the top left 
most pixel of the image. In JavaFX, the texture coordinate system for 3D 
objects is defined with its U axis increasing from left to right and the 
V axis increasing from top to bottom. Hence a texture coordinate of (0, 
0) references pixel (0, 0), which is the top left corner of the texture, 
and a texture coordinate of (1, 1) references the bottom right corner of 
the texture. This system matches the layout of the image, which is 
stored such that the top-most row of pixels ends up in memory in row 0. 
It also matches with the default 3D coordinate system used in JavaFX 
where the X axis increases from left to right and the Y axis increases 
from top to bottom.

      We understand that this V-down coordinate system maybe confusing 
or hard to work with for some 3D content developers when using models 
that are defined with Y-up. We could add a V-up option (as a boolean 
property of Shape3D). If set, we would flip the texture coordinates when 
rendering, such that:  V' = 1 - V.

     However it is very late in this release to consider any more 
changes, so our plan is to add this option in a post FX 8 release if it 
turns out to be needed. Please let us know right away if there is a 
compelling need for V-up support in the FX 8 release.

- Kevin and Chien