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Raytracer

Building

This assignment was programmed in C and compiled on Windows using gcc via MinGW64. The standard -std=gnu99 is now enforced by the Makefile. It is verified that this code compiles on the CSELabs computers.

There are no dependencies on external libraries. For compatibility, libm.a is explicitly linked to, but should be part of the C standard library. This project is expected to be compiled with gcc with -std=gnu99 using the given Makefile. To build the project, run make all. This will create raytracer.exe which is the program to run.

Scene files

Input files may be located anywhere and may have any file extension

  • Comments are lines that begin with #. These are ignored.
  • Empty lines are ignored, as are lines containing only whitespace.
  • Lines without the required number of arguments or with too many arguments are errors. Each instruction must begin and end on the same line.
  • Each of the required fields must be present, but may be in any order. Each may only appear once. A file may contain 0 or more shape definitions.
  • All material fields must be defined before any shapes, but may be redefined arbitrarily later.

In this format, <vector> refers to a list of 3 decimals separated by whitespace, which respectively represent the x, y, and z coordinates of a vector. <color> refers to a list of 3 decimals, each of which are between 0.0 and 1.0, which respectively represent the red, green, and blue components of the color. <decimal> and <integer> may be any numbers.

Required fields

  • eye <vector>: The position of the viewing eye. This changes the absolute position of the viewer within the scene.
  • viewdir <vector>: The direction the viewer is looking. Shapes behind the viewer are not rendered. Must be nonzero.
  • updir <vector>: The rotation around the view direction. This changes the apparent "upwards" direction in the image by rotating the scene. Must be nonzero and noncolinear to the viewdir.
  • fovv <decimal>: The vertical field of view in degrees. Decreased field of view correlates with zooming in from the eye.
  • imsize <integer> <integer>: The dimensions of the image. Must be positive integers. Decimals will be rounded down. The proportion of the shapes in the image will not change but increased resolution is acquired at higher sizes.
  • bkgcolor <color>: The background color.
  • parallel: Render the scene using paralell projection.

Material properties

  • mtlcolor <color> <color> ka kd ks n alpha eta: The color of all subsequent shapes. May be redefined arbitrarily, but must be defined before any shapes. The first color is the diffuse color and the second is the specular highlight color. The ka, kd, and ks are respectively the ambient, diffuse, and specular reflectivity of the objects. n is the specular exponent. alpha defines the opacity from 0 to 1, with 0 being transparent and 1 being opaque. eta defines the index of refraction from 1 to infinity. 1.3 is dense and 2.6 is very dense.
  • texture <filename>: This loads the given P3 PPM file as a texture and applies it to all subsequent images. It assumes the filename is rooted at the current directory.

Light definitions

  • light <vector> type <color>: If the type is 0, this creates a directed light in the direction of the vector. If the type is 1 this creates a point light by interpreting the vector as a point. The light has the given color.
  • spotlight <vector> <vector> <decimal> <color>: This creates a spotlight. The two vectors are respectively the position and direction. The decimal is the angle of the light. The light shines the given color.

Shape definitions

  • sphere <vector> <decimal>: A sphere with the given center and radius. Nonpositive radius will cause the sphere to become invisible.
  • ellipsoid <vector> <vector>: An ellipsoid with the given center and dimension vector. Nonpositive dimensions will cause errors.
  • v <vector>: Defines a vertex at the point. Vertexes are referred to by index and begin from 1.
  • vt <x> <y>: Defines a texture coordinate x, y. Texture coordinates are defined by index and begin from 1. These are required if a texture is defined before any vertexes.
  • vn <vector>: Defines a vertex normal. These are optional, and are indexed from 1.
  • f v1/t1/n1 v2/t2/n2 v3/t3/n3: Defines a triangular face using right-hand rule. Texture coordinates and normals may be omitted. If both are omitted, the slash craracters may be removed, otherwise the slash characters / must remain.

Executing

To execute the program, run ./raytracer.exe input.scene where input.scene is a valid text file in the format described above, located anywhere on the file system. This will generate a file with the same base name as the input file and the suffix .ppm which shall be a P3-encoded ASCII PPM image containing the rendered scene. Render time will increase as the image size and number of objects increase.

raytracer.exe is not compiled in debug mode for speed. To enable debug mode, open the Makefile and enable the debug flags as described in comments. It is recommended to pipe stderr to a log file because lots of data are generated; such as ./raytracer.exe input.scene 2> error.log.

In general, any fatal errors will be reported on the terminal and an output image will not be generated.

Documentation

The code is documented using Doxygen-compatible commenting. To create the documentation webpage, run make doc and launch doc/html/index.html in a web browser. You must have doxygen installed.

Doxygen-style documentation is found in header files and the main file. The implementation files also contain comments, but not Doxygen comments.

Cleanup

To delete build files, run make clean. To delete all generated files, run make spotless.