From: teunis <teunis@computersupportcentre.com>
  To  : 'ggi-develop@eskimo.com' <ggi-develop@eskimo.com>
  Date: Thu, 20 Aug 1998 21:06:48 -0700 (MST)

RE: LibGGI3D RFC

On Thu, 20 Aug 1998, Jon M. Taylor wrote:

> On Thu, 20 Aug 1998, Paul Sargent wrote:

[clip]

> > Walking along the edges of a 2D triangle and filling
> > in the raster spans from one edge to the other. You can't get any
> > simpler.
> > 
> > We would be talking about implementing a handful of commands: glBegin /
> > glEnd, glColor, glVertex2. That is what you need for rasterisation only.
> > Simple. Can be optimised to death
> 
> 	Of course this kind of code will be present.  But it will be in
> the display targets.

hmm..  The more I think about this the more I think that something like
that -specific- commandset fits libGGI3D....
But I could be wrong....

> > > 	Shading and texture mapping is included with the pluggable
> > > shaders. 
> > 
> > I like this pluggable shaders thing. Although I've still got to get my
> > head around it completly. Sound like it will be a software only thing.
> > Is that right? (I 'spose apart from the standard ones like flat, gourad,
> > gourad + Z, gourad + Texture, etc)
> 
> 	The shader functions themselves will be software-only, because a
> "shader function" for hardware shading is a meaningless concept.  What the
> pluggable shaders concept gives you is a way to separate shading from
> rendering.  If I call DrawTriangle() and tell it to use a phong shader, it
> can transparently use hardware color ramps if available, or fall back to
> the software phong shader I passed it.  And I don't need a separate
> DrawPhongShadedTriangle() function either.

And this is where I got mixed up.
I've been looking at -only- rendering functions.  Not shading.
hmmm.  That does put new light on things!

A perpixel shader is a silly thing to have in a game (IMHO) but nice for
high-quality rendering.  On the flip side, a shader that says "mix this
fog effect into those colours and that lighting produces a gouraud-shaded
triangle "so" for the renderer" :)
[and where HW supports it the shader just says "do this with a direct
renderer in HW", yes?]

G'day, eh? :)
	- Teunis