CVS additions that I promised...

[Kevin Harris]

I have added my collection of changes into the CVS tree.  And yes, I have
included example scenes to show how things may be done.

The support for area lights is not complete (meaning finished enough to be
accurate), but what I have checked in does work, and there is no added
penalty for 'pure' light sources (even those included in an aggregate or 
CSG).  

Sorry to anyone working on the raytracer, or writing some other renderer,
as I did change the interface required to be a renderer. :(

If anyone has any problems with my additions, let me know.  

As always, comments, questions, and complaints are welcome.

-Kevin-

Here's the list of my changes/additions (brief):
hlapi/aggregate.h,hlapi/aggregate.h --
  Added functions to be able to determine (via attributes) if an
  object is an aggregate (this includes CSG), and if the aggregate
  contains any objects.  The added attribute is 'containsobjects' and
  will be set to true if the object contains other objects.

  Also added a function to be able to determine if an aggregate
  contains a given object (via function call, not attributes).

hlapi/box.h,hlapi/box.cpp -- 
  Added a function to find a random point on the surface.  This is a
  uniform random (if the frand is uniform).

hlapi/circle.h,hlapi/circle.cpp -- 
  Added a function to find a random point on the surface.  This is a
  uniform random (if the frand is uniform).

hlapi/sphere.h,hlapi/sphere.cpp -- 
  Added a function to find a random point on the surface.  This is a
  uniform random (if the frand is uniform).

hlapi/torus.h,hlapi/torus.cpp --
  Added a function to find a random point on the surface.  This is NOT
  a uniform random.

hlapi/triangle.h,hlapi/triangle.h.cpp --
  Added a function to find a random point on the surface.  This is NOT
  a uniform random.

llapi/atmosphereic_object.cpp --
  Changed the evaluateScattering function to have a constant TLight
  pointer (it is not, and should not be changed).

llapi/entity.h -- 
  Added a function to explicitly set the location.

llapi/light.h,llapi/light.cpp --
  Changed the parent class of TLight from TEntity to TObject.  This is
  to allow pure lights to be stored in aggregates, csg, etc. (although
  putting them in an intersection or difference doesn't make much
  sense).

  Added an attribute called 'lightonly' which will be set to true if
  the object is a 'pure' light source (ie. has no shape).

llapi/material.h,llapi/material.cpp --
  Removed the 'tSelfEmission' scalar (never used), and replaced it
  with a pattern called 'ptEmission'.  Materials default to having no
  emission (the ptEmission pointer set to NULL).

  Added an 'emission' function, which will return the emission of the
  material for the given surface data.

llapi/object.h --
  Added a virtual function to return a random point on the surface.
  The base function is completely stupid (for right now--it will be
  replaced with something decent in the future), and returns
  the point <0,0,0>.  Note that the point is in LOCAL space, and
  should be transformed by the object's transform matrix.

llapi/renderer.h --
  Added a pure virtual function to calcualte the direct light from an
  area light.

llapi/scene.h,llapi/scene.cpp --
  Added a vector of area lights (TObject*), and a function to add
  them.

  Also, added a function to recursively locate lights from inside any
  object, and add them automatically. 

plugins/image_filter/lens_flare/if_lens_flare.cpp --
  Changed the ptLight variable in 'flaresByLightsources' to be const.

plugins/renderer/raytracer/raytracer.h,
plugins/renderer/raytracer/raytracer.cpp --
  Added functions to trace shadow rays to area lights, and to get the
  direct light from an area light.

  Made a few temporary changes (labeled with FIXME) to allow objects
  to emit light when an object is hit with a ray.

plugins/renderer/zbuffer/zbuffer.h,
plugins/renderer/zbuffer/zbuffer.cpp --
  Added the required function to be a renderer (direct light with an
  area light).

plugins/scene_io/rt/parser.y --
  Changed this to allow adding lights from outside the scene portion,
  or within any object that can hold other objects.

plugins/scene_io/rt/parser_defs.h --
  A change to allow something in the parser to be able to print out an
  error with a string instead of just a char*.


Additions:
scenes/light/night2.rt --
  A scene similar to that in night.rt, except the stars are grouped
  together in an aggregate, and the light for each pole is added to
  the top of it (defining the lamp post as an aggregate).  Note that
  the lights are NOT identical to those in night.rt, as those all have
  different halo parameters, and these are all identical (even the
  ones in the distance).

scenes/lights/area_light1.rt,scenes/lights/area_light2.rt --
  Some example scenes using area lights.


scenes/misc/lamp.rt -- 
  An example scene using area lights... A model of the lamp by my
  computer. 

scenes/misc/lamp_point.rt --
  The same scene as lamp.rt, but using point lights.  This is to show
  the differences in point lights and area lights.