Re: More thoughts on transparent depth sorting

[Frank C <li...@si...>]

On 9-Aug-04, at 3:01 PM, James W. Walker wrote:

> Frank C <li...@si...> wrote:
>
>> Meshes with intersecting bounds would have to have their triangles
>> lumped into the same list, but the fact that intersecting triangles
>> aren't split means this scenario will rarely work no matter what
>> sorting method is used.
>
> This isn't a big objection, but intersecting bounding boxes do not 
> imply intersecting triangles.  For instance consider nested boxes.

True, but my point was that intersecting meshes would have to be lumped 
together and sorted per triangle regardless if they contained 
intersecting triangles (that way it will work for cases like nested 
boxes).

>> 1. A "no sort" flag can be used on objects that require absolutely
>> no self-sorting; e.g. billboards, or meshes that use additive
>> blending.
>
> Meshes that use additive blending?  Such a thing does not currently 
> exist in Quesa, right?

It does, but it's not explicit. A transparent texture that isn't 
pre-multiplied with its alpha channel results in an additive blend. 
This means any texture may blend only partially additively, so 
unfortunately we don't have a way to automatically detect full additive 
blends.

Frank.