Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!olivea!apple!uokmax!stparker
From: stparker@uokmax.ecn.uoknor.edu (Steve Parker)
Newsgroups: comp.graphics
Subject: Re: Scene Description Standard (Renderman isn't good enough)
Message-ID: <1991May1.161329.26495@uokmax.ecn.uoknor.edu>
Date: 1 May 91 16:13:29 GMT
References: <1991Apr30.211131.7166@nntp-server.caltech.edu>
Organization: Engineering Computer Network, University of Oklahoma, Norman, OK
Lines: 132

woolstar@nntp-server.caltech.edu (John D. Woolverton) writes:

>   Perhapse to the world of 3D Z-buffers and other scan line
>rendering programs, RenderMan is enough.  But for work in
>RayTracing and beyond, there are too many things missing.

>   PLEASE SOMEONE!  Work on a scene description file format
>that will describe an animation or scene, not just the
>resultant list of polygons.


    Well, I am not Mr. Computer Graphics expert yet, but I am working
diligently on being one.  For the last four months, I have been busily
working on my own raytracing program.  I have spent most of that time
working on an input language.

    I find the same shortcomings in current file formats - They stink
for animation.  If I have a large scene, I want to read it in *once*
and generate hundreds of views or variations of the one scene.

    Computers are getting fast enough to make ray traced animations
even more feasible.

    With these observations, I set out to design my input language.
I have come up with an interpretive type language which has proved to
be very powerful and very expandable.   At the bottom, I have attached
a short piece of code which  renders a CSG face.  I would appreciate any
inputs or *constructive* criticisms.

    Much of my language is incomplete, but some of the features which
will be implemented include:

	- if else contstructs
	- for and while loops
	- Object copying.
	- Default object values
	- Object paths and camera paths - for motion blur
	- Built in matrix and vector manipulation

    One feature that I like is that I can add a primitive without
changing the yacc or lex code.  I simply put the name of the new primitive
in a file, write all of the associated routines, add it to the Makefile
and type make.

    The language is really powerful in my opinion, but what do I know?

    I do not want to bore the entire group with the gory details, but
I can supply more information if anyone would like it.

    Again, I would appreciate any input.

		Steve Parker
		sgp@phyast.nhn.uoknor.edu





/*
 * render a CSG face
 */

/*
 * Note: the names light1, light2, and light3 are not special, they
 *       are simply variable names which are assigned to the lights.
 *       They could have just as easily been Larry, Curly and Moe.
 */
light1=light_source(POSITION={0,-10,30},BRIGHTNESS=1,COLOR=[1,1,1],TYPE=Point);
light2=light_source(POSITION={0,-10,-10},BRIGHTNESS=.8,COLOR=[1,1,1],TYPE=Point);
light3=light_source(POSITION={0,-1000,0},BRIGHTNESS=.8,COLOR=[1,1,1],TYPE=Point);
lighting(SOURCE=light1,SOURCE=light2,SOURCE=light3);

/*
 *  The idea behind these is that they will be pretty much the same for
 *  most cameras
 * 
 */
params=parameter(SUPERSAMPLING=Jittered, SAMPLES=1, MAX_RAYTREE_DEPTH=4,
              CUTOFF_THRESHOLD=.001, SHADOWS=True);

camera1=camera(EYE_POINT={1,-4,0},LOOK_POINT={0,0,0},UP_VECTOR={0,0,1},
              FOV=45, XRESOLUTION=250, YRESOLUTION=250,
              XOUTPUT=True, TITLE="Michele's Face",
              OUTFILE="face.rle",PARAMETERS=params);

/*
 * Set up surfaces
 */
mouthsurf=surface(AMBIENT=[.01,.01,.01],DIFFUSE=[.8,.01,.01],SPECULAR=[.9,.9,.9],
              SR_COEFF=25, REFLECTIVITY=.7, TRANSPARENCY=0);
nosesurf=surface(AMBIENT=[.01,.01,.01],DIFFUSE=[.7,0,.5],SPECULAR=[.9,.9,.9],
              SR_COEFF=25, REFLECTIVITY=.9, TRANSPARENCY=0);
eyesurf=surface(AMBIENT=[.01,.01,.01],DIFFUSE=[.5,.3,.9],SPECULAR=[.9,.9,.9],
              SR_COEFF=25, REFLECTIVITY=.6, TRANSPARENCY=0);
facesurf=surface(AMBIENT=[.01,.01,.01],DIFFUSE=[.9,.7,.5],SPECULAR=[.9,.9,.9],
              SR_COEFF=25, REFLECTIVITY=.4, TRANSPARENCY=0);
hairsurf=surface(AMBIENT=[0,0,0],DIFFUSE=[.5,.5,.5],SPECULAR=[0,0,0],
              SR_COEFF=25, REFLECTIVITY=.1, TRANSPARENCY=0);

/*
 * Create the primitives.  Again face, left_eye, right_eye, etc. are
 * just variable names
 *
 */
face=sphere(POSITION={0,0,0},RADIUS=1.2, SURFACE=facesurf);
left_eye=sphere(POSITION={-.5,-.8,.6},RADIUS=.3,SURFACE=eyesurf);
right_eye=sphere(POSITION={.5,-.8,.6},RADIUS=.3,SURFACE=eyesurf);
left_nose=sphere(POSITION={-.2,-.95,0},RADIUS=.4,SURFACE=nosesurf);
right_nose=sphere(POSITION={.2,-.95,0},RADIUS=.4,SURFACE=nosesurf);
mouth_top=sphere(POSITION={0,-1.32,.15},RADIUS=1,SURFACE=mouthsurf);
mouth_bot=sphere(POSITION={0,-.82,-.1},RADIUS=.8,SURFACE=mouthsurf);

/*
 * CSG operations
 */
eyes=left_eye+right_eye;
nose=left_nose&right_nose;
mouth=mouth_bot-mouth_top;

/*
 * A background color may also be specified here
 */
world(OBJECT=(face-eyes)+(mouth+nose));

/*
 * Render the image
 */
render(CAMERA=camera1);

/* And we could then continue and render another view, add objects, or
 * just render something else completely different altogether
 */