Re: [Plib-devel] Release 1.8.5....and a glimpse of the future.

[Steve B. <st...@sj...>]

John F. Fay wrote:
> Alas!  Poor PUI.  I knew him, Horatio.
>
> I really don't have much to complain about.  My PUI application has been 
> retired for a couple of years now and I've been given new projects at work. 
>  But I hate to let go of things that I have worked on.
>   
The trouble is that PUI has grown from a very minimal way to toss a 
handful of buttons onto the bottom of a screen full of 3D graphics into 
a fully grown scene-graph API - it has branch nodes and leaf nodes and 
traversals and culling, rendering states, geometry - and that's exactly 
what SSG has to have.  Layering PUI on top of SSG makes sense because 
they can share code and PUI can have textured, lit, bumpmapped, 
animated, glowing buttons...who knows what?

The whole of PUI is based on the OpenGL 1.x 'standard pipeline' API and 
that's going away (or at least it's not going to be The One True Way To 
Do Graphics).  So in the next year or two we'll really be forced to 
either rewrite a chunk of PUI or see it go utterly obsolete.  At the 
very least the bottom end renderer has to change to use blocks of vertex 
data and shaders.   The PUI API is particularly ill-suited to that 
because it doesn't use the concept of "rendering state" - it just has a 
bunch of ad-hoc data scattered throughout the scene graph.   It 
generates geometry on-the-fly from the sizes of the widgets - but what 
we really need is precalculated vertex tables at each node.  That means 
it has to know how to build and maintain those things - shared states 
means ref-counting and such.  Shaders need to be compiled and have 
mechanisms to pass uniform data to them.  None of that stuff exists in PUI.

However, the new, improved SSG will be PERFECT for that stuff.  If it 
has 'plugin' capability as I'm planning - then PUI simply builds an SSG 
scene graph and plugs in it's own culling mechanisms.   SSG provides the 
geometry maintenance, shader services, etc.  It's a good match.

I don't think it'll suffer too badly in the transition...but I don't 
plan on ripping into PUI for a while - I've got to get the new SSG 
working well first.