From: Jon M. Taylor <taylorj@ecs.csus.edu>
  To  : ggi-develop@eskimo.com
  Date: Wed, 19 Aug 1998 13:23:20 -0700 (PDT)

Re: LibGGI3D RFC

On Wed, 19 Aug 1998, Andrew Apted wrote:

> Jon writes:
> 
> >  III. Design specifics.
> >  
> >  * struct camera { float x1, y1, z1, x2, y2, z2 }. Every LibGGI3D display
> >  will have a camera struct attached to it.  A generic hook for arbitrary
> >  display data should also be present - the shaders might use it.  void
> >  *private_data. 
> 
> I guess x1,y1,z1 is the camera position, and x2,y2,z2 is the normal to
> the viewplane, but what about the orientation of the viewplane (the "up"
> vector for want of the precise term) ?

	On reflection, I think I will have an observer X, Y, Z and a view
orientation theta, phi, alpha.

> >  * int DrawTriangle (float x1, y1, x2, y2, x3, y3; shader_index shader; void
> >  *shader_data) is the core drawing function.
> 
> Are those coordinates on the screen ?  Or should they be world space and
> have z1,z2,z3 as well, where DrawTriangle() does the translation of
> world space to screen space ?

	Argh!  I need to post on a full stomach |->.  yeah, there should 
be Z1, Z2, Z3 there as well (world space).

Jon

---
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