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Programming Assignment 3: Basic Ray-Tracing
Summary
You will write a simple
ray tracing program. Your program should produce images that exhibit diffuse
reflection (using Lambert's law and ambient light), specular reflection, and
shadows. The program should be able to render spheres and polygons.
Due Date
The assignment is due on
Monday, April 7 at 11:59 PM. The standard late policy
for programs is in effect.
Required Features
- The program should be written in C/C++ using
openGL and GLUT. However, note that very few features of openGL/GLUT
will be used. You will only use GLUT to create an interface window, and
use openGL to draw 2D pixels within that window. Your program will do
all the necessary calculations to determine the color of each pixel in the
window.
- The program should take a single command-line
argument - the name of the input file (see the next bullet).
- The scene will be specified in a file as
follows (this is for your information only; you will be given code to
parse this file):
- VIEW z-position
- LIGHT x y z red green blue
- SPHERE x y z radius red green blue
- POLY #vertices x1 y1 z1 x2 y2 z2 x3
y3 z3 ... red green blue
- There will be a limited number of objects
(given by constants in the provided skeleton code) specified in the
file. You will be given routines that read this file and place the
information into data structures.
- For the view, assume that the eyepoint is on
the positive z-axis, looking back toward the origin (in the negative
z-direction). The window is centered at the origin and is 2x2 (-1.0,
-1.0) to (1.0, 1.0). The view should be a standard perspective
projection.
- You will be provided with the following files:
- read_input.c: Routines to read the input file
- ray_trace.h: Globals and data structures
- ray_trace.c: Some skeleton code
- P3_input: a directory containing sample input files
on which your program will be partially graded
- All of these files are available in this zip archive.
- Your job is to fill in the functions that
calculate intersections between rays and objects, and that determine the
illumination (color) at each pixel.
- You are required to include the ability to
render spheres and polygons correctly, including ambient, diffuse, and
specular illumination, and shadows caused by objects occluding the light
source from a particular point.
- Test your program on scenes containing up to
two light sources, up to three spheres, and up to two polygons. Your
program will be graded on whether it runs and renders objects (40%),
whether the illumination and shadowing "look good" (40%) and
on documentation (20%). "Looking good" is obviously a
subjective measure, but we will be looking for even shading, correct
shadows, appropriate ambient lighting, good choices for the diffuse
coefficient and specular values, etc.
- Ray-tracing programs can have long execution
times. You may wish to debug your program using a lower resolution
(small screen window to which you are mapping your 2x2 view window) for
faster execution times (since you will be calculating the values of each
pixel of the interface window).
- This PDF file
has sample images for scenes 1, 2, and 3 (spheres only, as well as
spheres and polygons).
Optional Features (for up to 10 bonus points)
- Provide an interface allowing the user to
change the values of the illumination model constants and re-render the
scene.
- Provide an interface allowing the user to
change the material properties of individual objects in the scene.
- Render the same scene using openGL 3D graphics
and lighting in a separate window for comparison purposes.
- Make some objects partially transparent.
- Add an acceleration algorithm to speed up the
intersection calculations. See the instructor if interested in this
option.
Submission
Turn in your program via email to the TA. You may either submit a
single source file or a ZIP archive of several source/header files. You may
also optionally include a plain text README file if you wish.
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