SingleSource/Benchmarks/SmallPT/README - llvm-test-suite - Git at Google


            
            TITLE


            smallpt: Global Illumination in 99 lines of C++


            CREDITS


            Author: Kevin Beason (kevin.beason [at] gmail.com)

            
            Date: 10/11/2008


            SUMMARY


            smallpt is a small Monte Carlo path tracer, and generates a single image of a

            
            modified Cornell box rendered with full global illumination (GI). It does this

            
            by solving the rendering equation, including ideal Lambertian, specular, and

            
            dielectric reflection, area lights, anti-aliasing, importance sampling, and

            
            multi-threading. It is only 99 lines of C++, but illustrates photo realistic

            
            rendering in a correct, and concise manner.


            DESCRIPTION


            The source code for a small program that path traces a simple Cornell box and

            
            produces accurate results in a terse implementation is given, which provides an

            
            educational example to new graphics students (and seasoned alike), and yields a

            
            ground truth image, all in an easy to read package. Never before has a correct,

            
            complete, and functioning path tracer been presented so succinctly. Readers

            
            will see ray-sphere intersection, Monte Carlo path tracing, Russian roulette,

            
            importance sampling, anti-aliasing, and OpenMP multi-threading in a concrete

            
            working example, which may be read from beginning to end in a single

            
            sitting. The program compiles with GCC 4.2 down to a 16k executable and

            
            produces a 1024x768 resolution image using 5000 paths in 2 hours on an Intel

            
            Core 2 Quad machine. With slight modifications (smallpt4k.cpp) the code compiles to

            
            under 4KB.


            FEATURES


            * Global illumination

            
            * Unbiased Monte Carlo path tracing

            
            * Cornell box scene description

            
            * Ray-sphere intersection

            
            * Soft shadows from diffuse luminaire

            
            * Specular, Diffuse, and Glass BRDFs

            
            * Cosine importance sampling of the hemisphere for diffuse reflection

            
            * Russian roulette for path termination

            
            * Russian roulette for selecting reflection or refraction for glass BRDF

            
            * Antialiasing via super-sampling with importance-sampled tent distribution,

            
              and 2x2 subpixels

            
            * Automatic multi-threading using OpenMP

            
            * Less than 100 lines of 72-column code

            
            * With provided code changes, can compile to 4K binary


            BUILDING


            There are two versions of smallpt. The basic version is called "smallpt"

            
            (smallpt.cpp), and is 99 lines. A second version, "smallpt4k" (smallpt4k.cpp),

            
            is 102 lines but compiles to 4K instead of 16KB. It is just a

            
            proof-of-concept. They compute slightly different images due to compiler optimization differences.

            
            The 4 KB version takes 30% longer.


            1) Modify top of Makefile to select the correct compiler.

            
            2) "make smallpt" (This builds both the regular version)

            
            3) "make smallpt4k"  (This builds the 4K version. Requires sstrip, see Makefile.)


            USAGE


            The program takes one argument, the number of samples per pixel. This value

            
            must be greater than 4 to accommodate the 2x2 subpixel grid. For example,

            
            the included reference image was generated with:


                 time ./smallpt 5000


            This took 124 minutes (2 hours) on a Intel Core 2 Quad Q6600 2.4GHz machine

            
            running Kubuntu Linux (32-bit Gutsy).


            The tiny version takes no arguments (5000 samples/pixel is hard coded):


                time ./smallpt4k


            Compilation requires gzip and ELFkicker's sstrip command. See the Makefile for

            
            details. It executes in slightly longer time, and yields a slightly different

            
            image due to compiler optimizations differences.


            The time command tells you how long the render takes and is optional. You can

            
            view the image with most any image viewer. For example, if you have ImageMagick

            
            installed:


                display image.ppm


            MORE INFO


            MINILIGHT - a minimal global illumination renderer, by Harrison Ainsworth

            
            A similar, earlier project. More general but also larger (100x). The site has

            
            some good information on Monte Carlo path tracing. Instead of repeating it

            
            here, the reader is referred to that site:

            
            http://www.hxa7241.org/minilight/minilight.html


            Realistic Ray Tracing by Peter Shirley

            
            Almost 100% of smallpt is derived from this book.

            
            http://www.amazon.com/Realistic-Ray-Tracing-Peter-Shirley/dp/1568811101


            Henrik Wann Jensen's Cornell box images

            
            The inpiration of the output generated by smallpt.

            
            http://graphics.ucsd.edu/~henrik/images/cbox.html


            100 lines C++ sphereflake raytracer, by Thierry Berger-Perrin

            
            Ray sphere intersection code stolen from here. (No full GI.)

            
            http://ompf.org/ray/sphereflake/


            sf4k, also by Thierry Berger-Perrin

            
            Idea for 4K-ness. (No full GI.)

            
            http://ompf.org/stuff/sf4k/


            C++ vs OCaml: Ray tracer comparison, by Jon D. Harrop

            
            105 line C++ ray tracer. (No full GI.)

            
            http://www.ffconsultancy.com/languages/ray_tracer/comparison.html


            Introduction to Linux as 4 KB Platform

            
            Some information regarding shrinking binaries to 4KB on Linux .

            
            http://in4k.untergrund.net/index.php?title=Linux
	TITLE

	smallpt: Global Illumination in 99 lines of C++

	CREDITS

	Author: Kevin Beason (kevin.beason [at] gmail.com)
	Date: 10/11/2008

	SUMMARY

	smallpt is a small Monte Carlo path tracer, and generates a single image of a
	modified Cornell box rendered with full global illumination (GI). It does this
	by solving the rendering equation, including ideal Lambertian, specular, and
	dielectric reflection, area lights, anti-aliasing, importance sampling, and
	multi-threading. It is only 99 lines of C++, but illustrates photo realistic
	rendering in a correct, and concise manner.

	DESCRIPTION

	The source code for a small program that path traces a simple Cornell box and
	produces accurate results in a terse implementation is given, which provides an
	educational example to new graphics students (and seasoned alike), and yields a
	ground truth image, all in an easy to read package. Never before has a correct,
	complete, and functioning path tracer been presented so succinctly. Readers
	will see ray-sphere intersection, Monte Carlo path tracing, Russian roulette,
	importance sampling, anti-aliasing, and OpenMP multi-threading in a concrete
	working example, which may be read from beginning to end in a single
	sitting. The program compiles with GCC 4.2 down to a 16k executable and
	produces a 1024x768 resolution image using 5000 paths in 2 hours on an Intel
	Core 2 Quad machine. With slight modifications (smallpt4k.cpp) the code compiles to
	under 4KB.

	FEATURES

	* Global illumination
	* Unbiased Monte Carlo path tracing
	* Cornell box scene description
	* Ray-sphere intersection
	* Soft shadows from diffuse luminaire
	* Specular, Diffuse, and Glass BRDFs
	* Cosine importance sampling of the hemisphere for diffuse reflection
	* Russian roulette for path termination
	* Russian roulette for selecting reflection or refraction for glass BRDF
	* Antialiasing via super-sampling with importance-sampled tent distribution,
	and 2x2 subpixels
	* Automatic multi-threading using OpenMP
	* Less than 100 lines of 72-column code
	* With provided code changes, can compile to 4K binary

	BUILDING

	There are two versions of smallpt. The basic version is called "smallpt"
	(smallpt.cpp), and is 99 lines. A second version, "smallpt4k" (smallpt4k.cpp),
	is 102 lines but compiles to 4K instead of 16KB. It is just a
	proof-of-concept. They compute slightly different images due to compiler optimization differences.
	The 4 KB version takes 30% longer.

	1) Modify top of Makefile to select the correct compiler.
	2) "make smallpt" (This builds both the regular version)
	3) "make smallpt4k" (This builds the 4K version. Requires sstrip, see Makefile.)

	USAGE

	The program takes one argument, the number of samples per pixel. This value
	must be greater than 4 to accommodate the 2x2 subpixel grid. For example,
	the included reference image was generated with:

	time ./smallpt 5000

	This took 124 minutes (2 hours) on a Intel Core 2 Quad Q6600 2.4GHz machine
	running Kubuntu Linux (32-bit Gutsy).

	The tiny version takes no arguments (5000 samples/pixel is hard coded):

	time ./smallpt4k

	Compilation requires gzip and ELFkicker's sstrip command. See the Makefile for
	details. It executes in slightly longer time, and yields a slightly different
	image due to compiler optimizations differences.

	The time command tells you how long the render takes and is optional. You can
	view the image with most any image viewer. For example, if you have ImageMagick
	installed:

	display image.ppm

	MORE INFO

	MINILIGHT - a minimal global illumination renderer, by Harrison Ainsworth
	A similar, earlier project. More general but also larger (100x). The site has
	some good information on Monte Carlo path tracing. Instead of repeating it
	here, the reader is referred to that site:
	http://www.hxa7241.org/minilight/minilight.html

	Realistic Ray Tracing by Peter Shirley
	Almost 100% of smallpt is derived from this book.
	http://www.amazon.com/Realistic-Ray-Tracing-Peter-Shirley/dp/1568811101

	Henrik Wann Jensen's Cornell box images
	The inpiration of the output generated by smallpt.
	http://graphics.ucsd.edu/~henrik/images/cbox.html

	100 lines C++ sphereflake raytracer, by Thierry Berger-Perrin
	Ray sphere intersection code stolen from here. (No full GI.)
	http://ompf.org/ray/sphereflake/

	sf4k, also by Thierry Berger-Perrin
	Idea for 4K-ness. (No full GI.)
	http://ompf.org/stuff/sf4k/

	C++ vs OCaml: Ray tracer comparison, by Jon D. Harrop
	105 line C++ ray tracer. (No full GI.)
	http://www.ffconsultancy.com/languages/ray_tracer/comparison.html

	Introduction to Linux as 4 KB Platform
	Some information regarding shrinking binaries to 4KB on Linux .
	http://in4k.untergrund.net/index.php?title=Linux