Phongo Clap RT

... see documentation: http://ramonblanquer.com/doc/phongo/index.html

Brief

My project consists on a raytracing offline renderer. This is what I handed in but I will be extending it to features like path tracing. A full list about the further things I would like to do are listed after the usage section. My raytracer features:

• Sphere-Ray Intersections
• Plane-Ray Intersections
• Lighting decay
• Raytraced Shadows
• Reflection
• Refraction
• Phong Shading Model
• Antialiasing
• File parsing

Usage

Its usage is fairly simple. You just have to run the binary followed by the path where the scene file is located. Read carefully how the syntax works on the next section because it is not particulary straight-forward due to my lack of knowledge with parsing frameworks.

./clap [path to scene text file]

I recommend building your binary from source code to make sure that it will work on your system. For that you will need qmake and git. If you want to try Phongo Clap on your computer run these commands. However I also include a previously built binary just in case.

git clone https://github.com/NCCA/docwhite-CA1
cd docwhite-CA1/FinalSubmission
qmake
make
./clap scene_file.txt

Scene File Syntax

Please read this section carefully. I would first suggest you to take a look at a sample image file that I included with the project. Scene files consist on three parts: a header, the lights interface and the objects interface.

Scene File Sample [scene_file.txt]

NAME "colorful" DIMENSIONS ["500" "500"]
CAMERA ["0", "1", "-2"] ["0", "0", "6"]
DEPTH "4" ANTI-ALIASING "4"

Lights
{
    +light1 [ 5 5 3 ] [ 0.347 0.89 0.78 ] [ 0.347 0.89 0.78 ] 2 2 1
    +light2 [ -5 5 4.2 ] [ 1 1 1 ] [ 1 1 1 ] 2 2 1
    +light3 [ 0.9 2 -1 ] [ 1 1 1 ] [ 1 1 1 ] 0.2 0.2 1

+}

Objects
{
    $Plane plane1 -1 [ 0 1 0 ] @checker [ 0 0 0 ] [ 1 1 1 ] @specularHardness 4

    $Plane plane2 -4.90 [ 0 1 -1 ] [ 1 1 0 ] /

    $Sphere sphere1 [ 0 0 2 ] 0.8 [ 1 0 1 ] @specularHardness 5

    $Sphere sphere2 [ -1 1.2 0.2 ] 0.5 [ 0.1 0.4 0.95 ] @reflective 70

    $Sphere sphere4 [ 1.1 0.5 2.0 ] 0.1 [ 0 1 0 ] @refractive 1.2 100

    $Sphere sphere5 [ 0.7 0.95 0.3 ] 0.15 [ 1 1 0 ] @specularHardness 100

    $Sphere sphere6 [ 1.1 0 4.0 ] 0.1 [ 0.2 1 0.14 ] @specularHardness 100

    $Sphere sphere7 [ -0.9 0.15 0.8 ] 0.3 [ 1 0 0 ] @refractive 1.2 100

    $Sphere sphere8 [ 0.5 0.3 0.2 ] 0.2 [ 0 0.8 1 ] @refractive 1.2 100

    $Sphere sphere9 [ 0.3 1.4 3.2 ] 0.53 [ 1 0.4 0.2 ] @reflective 60
$}

Header

The header part contains the information about what the name of the project is, the dimensions, camera, depth and antialiasing. Each property consists of VARIABLE "VALUE" or VARIABLE ["VALUE" "VALUE"]. And they need to be declared as follows. Please copy and paste this to your text file to avoid problems and simply change the values.

NAME "fileName" DIMENSIONS ["width" "height"]
CAMERA ["posX", "posY", "posZ"] ["aimX", "aimY", "aimZ"]
DEPTH "recursive_depth" ANTI-ALIASING "aa"

• replace the lowercase words with values, leaving the quotes " "

For the lights interface each light declaration and definition should be started by +, and everything should be wrapped as Lights { [all the lights] +} (do't forget the + before the closing brace). The definition follows this pattern:

+light_name [ posX posY posZ ] [ diffR diffG diffB ] [ specR specG specB ] diffInt specInt falloff

PLEASE note that the first and last values of each tuple are seppared using a SPACE, if you do it like [posX posY posZ] it will break, same if you do it like [ posX posY posZ].

Where

• light_name is self-explanatory
• posX, posY, and posZ refer to the light's position.
• diffR, diffG, diffB [0-1] value refer to the diffuse colour.
• specR, specG, specB [0-1] value refer to the specular colour.
• diffInt the amount of diffuse contribution emmited by the light.
• specInt amount of specular the light emits.
• falloff decay amount.

Here there is an example:

Lights
{
    +light1 [ 5 5 3 ] [ 0.347 0.89 0.78 ] [ 0.347 0.89 0.78 ] 2 2 1
    +light2 [ -5 5 4.2 ] [ 1 1 1 ] [ 1 1 1 ] 2 2 1
    +light3 [ 0.9 2 -1 ] [ 1 1 1 ] [ 1 1 1 ] 0.2 0.2 1
+}

The object interface is similar. Everything is between Objects { [...] $} (do not forget dollar sign before closing brace). We can declare either planes or spheres.

Planes

A plane can be of two types, a checkerboard plane or a regular plane. To define a regular plane do it as follows:

$Plane plane_name dist [ nX nY nZ ] [ cR cG cB ]

PLEASE note that the first and last values of each tuple are seppared using a SPACE, if you do it like [nX nY nZ] it will break, same if you do it like [ nX nY nZ].

Where

• plane_name is self explanatory.
• dist is the distance from the origin.
• nX, nY, nZ (no need to normalize, it's done for you) are the normal components of the plane.
• cR, cG, cB [0-1] values are the colour components of the plane.

For a checkerboard plane the definition is a bit different:

$Plane plane_name dist [ nX nY nZ ] @checker [ col1R col1G col1B ] [ col2R col2G col2B ]

Take a look at the @checker token. after the checker token the parser will be expecting two tuples of colours, do it as above, putting spaces even before the first element of the tuple.

You can set the plane to have certain specular hardness by the keyword @specularHardness [value]. Find some examples above.

Spheres

Spheres are pretty simple.

$Sphere sphere_name [ cX cY cZ ] rad [ colR colG colB ]

Where

• cX, cY, cZ are the world space coordinates of the sphere centres.
• rad is the radius of the sphere.
• colR, colG, colB are the colour values of the sphere.

Reflection

You can set reflection options using the keyword @reflective percentage where the percentage will determine how reflective the sphere is.

Refraction

Refraction settings are set @refraction index_of_refraction transparency where transparency is in %.

Sphecular hardness

Also you can set specular hardness for the objects that are not reflective or refractive. I did it that way because I did a trick to make the transparent/reflective objects look glossy. So if you use specular hardness you cannot use reflection or refraction.

You have to stick to this structure.

Documentation

http://ramonblanquer.com/doc/phongo/index.html

TO DO

• BRDF
• Implement SpotLight
• Ambient Occlusion
• Load OBJs
• Fresnel
• Depth of Field
• Implement OpenSubDiv
• Implement OpenEXR (just for fun)
• Stochastic Sampling to break aliasing a bit more
• Improve AA on refractions and reflections
• Make it multi-threaded
• Implement more light decays
• Implement Triangle-Ray intersection
• Improve shadows
• Implement more shapes
• Make specular compatible with refraction/reflection

Some Renders

... rendering with anti-aliasing value of 1

... rendering with anti-aliasing value of 16

... this happens if I don't clamp the light contributions to [0-1]

... same here. Not clamping the values produces interesting results!

... first tests when I implemented the Phong shader and tweaked it.

... my favourite render. The scene_file I include renders this.

Bibliography

Pharr, M. and Humphreys, G., 2010. Physically Based Rendering. Burlington: Morgan Kaufmann Publishers Haines E.

Glassner, A., 1989. An Overview of Ray Tracing In: Glassner, A., ed. An Introduction To Ray Tracing California: Academic Press, 1-31

Haines, E., 1989. Essential Ray Tracing Algorithms In: Glassner, A., ed. An Introduction To Ray Tracing California: Academic Press, 33-77

Hanrahan, P., 1989 A Survey of Ray-Surface Intersection Algorithms In: Glassner, A., ed. An Introduction To Ray Tracing California: Academic Press, 79-119

Glassner, A., 1989 Surface Physics for Ray Tracing In: Glassner, A., ed. An Introduction To Ray Tracing California: Academic Press, 121-160

Newman, W. 1975 Illumination for Computer Generated Pictures [online] [checked 2015] [http://www.cs.northwestern.edu/~ago820/cs395/Papers/Phong_1975.pdf]

Scratchapixel (no date) Introduction to Ray Tracing: a Simple Method for Creating 3D Images. Scratchpixel [online] [checked 2015] Available from: http://www.scratchapixel.com/lessons/3d-basic-rendering/introduction-to-ray-tracing

Scratchapixel (no date) Introduction to Ray Tracing: a Simple Method for Creating 3D Images. Scratchpixel [online] [checked 2015] Available from: http://www.scratchapixel.com/lessons/3d-basic-rendering/introduction-to-ray-tracing

Delphi3D (no date) Delphi3D [Archive]- Rapid OpenGL Development Delphi3D [online] [checked 2015] Available from: http://www.gameprogrammer.net/delphi3dArchive/phongfordummies.htm

**Phong, B. T.**r, 1975. Illumination for computer generated pictures [online] [checked 2015] Utah: Communications of ACM, 18. Available from: http://www.cs.northwestern.edu/~ago820/cs395/Papers/Phong_1975.pdf

cplusplus.com (no date) Input/output with files - C++ Tutorials cplusplus.com [online] [checked 2015] Available from: http://www.cplusplus.com/doc/tutorial/files/

Boris Schäling (2008-2015) Chapter 10. Boost.Tokenizer The Boost C++ Libraries [online] [checked 2015] Available from: http://theboostcpplibraries.com/boost.tokenizer

Siek, J. and Bandela J. R. (2000-2001) Boost Tokenizer Overview - 1.58.0 Boost C++ Libraries [online] [checked 2015] Available from: http://www.boost.org/doc/libs/1_58_0/libs/tokenizer/