"Improving Image-Space Caustics Via Variable-Sized Splatting"
                Chris Wyman, University of Iowa
            Carsten Dachsbacher, University of Erlangen


Running the demo:
-----------------

Unzip the package, goto the "\bin" directiory, run the executable 
"improvingImageSpaceCausticsDemo.exe"

Relevent commands:
    * Pressing "x" switches between caustic rendering techniques
          (Default = Approach of Wyman and Davis from I3D 2006)
    * Pressing "f" toggles on/off temporal filtering over 4 frames
    * Pressing "h" displays a help screen about other commands.
          (Note that rendering speed with help text displayed is
           quite variable, and often very slow)


Initial state:
--------------

This demo starts with a 512 x 512 window, with 4x supersampling 
(the final image is rendered at 1024 x 1024), a 512 x 512 buffer 
of photons, and a 512 x 512 caustic map.  You may change 
resolutions using the menu (right mouse).

Most options are configurable via key commands.  The most important
(and best tested/debugged) commands are documented via the help
screen (toggled by pressing "h").

In order to keep distribution size small, the basic demo package 
comes with data to only render a glass Beethoven bust.  Data for 
other example models can be downloaded separately.  Simply place
the data in the correct directories and the demo will add menu
options to load these additional refractive objects.


Demo requirements:
------------------

We developed our demo on nVidia GeForce 6800, 7800, and 7800 Go
cards, so it will work on those models with up-to-date drivers.
Because we use Cg for all our shaders, including various features
of Shader Model 3.0, it may not work (easily) on ATI cards.  This
is solely due to our development environment.

A (possibly non-exhaustive) list of OpenGL extensions explicitly 
used follows: 
     GL_ARB_VERTEX_PROGRAM
     GL_EXT_FRAMEBUFFER_OBJECT
     GL_ARB_DRAW_BUFFERS
     GL_ARB_VERTEX_BUFFER_OBJECT  
     GL_ARB_COLOR_BUFFER_FLOAT    
     GL_ARB_TEXTURE_FLOAT         
     GL_ARB_SHADOW                 
     GL_ARB_DEPTH_TEXTURE

A couple extensions are (or probably are) implicitly used by Cg:
     GL_ARB_FRAGMENT_PROGRAM
     GL_NV_FRAGMENT_PROGRAM2
     
For nVidia graphics cards, any 8x.xx series driver should work.
If not, update your drivers to an 82.xx, 83.xx, or later version.

Requires the GLUT utility toolkit (DLL included), full package 
available from:
  http://www.opengl.org/resources/libraries/glut.html

Requires the GLEW 1.3.2 OpenGL Extension library (DLL included), 
full package available from:
  http://glew.sourceforge.net

Requires nVidia's CG library, release 1.4 (DLLs included), full 
pacakage available from:
  http://developer.nvidia.com/page/tools.html


Source Code:
------------

Available upon request.  E-mail: cwyman@cs.uiowa.edu

Requests that appear to be from students doing term projects will 
be ignored.  If you are an unknown (to me) student and expect a 
response, please distinguish yourself from the student requests I 
get periodically, for instance by telling me why you need the code.

Code for this demo is (relatively) clean, though some crud still
remains from the numerous paper deadlines this work has passed 
through.  I have spent time commenting important parts of the code
reasonably well.  Shaders, however, are poorly documented.


Limitations:
------------

Because the caustics gather happens in light-space, only when
motion of objects or the light occurs, our caustic illumination
on Phong surfaces is *wrong* (because we do not know the 
direction to the eye at the time of the gather).  We use the
approximation that all illumination comes from the light (not
from points on the refractor).


Acknowledgements:
-----------------

Lightprobes from Paul Debevec (http://www.debevec.org/Probes/)

Models from all over, but particularly the Stanford 3D Scanning
Repository (http://graphics.stanford.edu/data/3Dscanrep/) and 
Hughes Hoppe's web page (http://research.microsoft.com/~hoppe/).