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C++ Raytracer

A very simple raytracer written in C++ as a final project for an introductory 3D graphics course.

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Features

Renders to a ppm a scene with the following characteristics:

  • Up to 15 spherical objects (sphere or ellipsoid)
  • Up to 10 lights
  • Background colour
  • Ambient colour
  • Multithreading support

The algorithm is a very similar but different application of the Phong reflection model (more can be read here). The number of reflection rays per pixel is no more than 3.

Planned Features

  • CUDA accelerated rendering
  • Render to a more web friendly image format
  • More shapes
  • More unit tests

Changelog (2019-08-19)

  • Improved multithreading performance (~25%)
  • Cleaned up redundant code
  • View fustrum parameters were deprecated. Aspect ratio is automatically calculated

Compilation

Clone repository and build in debug or release (x86 or x64) using Visual Studio 2017. Compiling in debug mode will also build the test project. Note: Currently the test inputs are copied to the output directory regardless of debug/release.

Usage

raytracer.exe <filename> -multi

filename must be a .txt file, contain the following, and the parameters are case sensitive. Order of each parameter does not matter. If a parameter is repeated, the most recent occurence takes precedence:

-multi Optional. Enables multithreading support and allocates threads relative to the number of hardware threads on your computer. Average performance gains of between 3x-5x. Scales best for larger images.

NEAR <n**>
~~LEFT <l**>~~
~~RIGHT <r**>~~
~~BOTTOM <b**>~~
~~TOP <t**>~~

RES <x*> <y*>

SPHERE <name^> <x**> <y**> <z**> <scl x**> <scl y**> <scl z**> <r***> <g***> <b***> <ka***> <kd***> <ks***> <kr***> <n*>

LIGHT <name^> <x**> <y**> <z**> <r***> <g***> <b***>

BACK <r***> <g***> <b***>
AMBIENT <r***> <g***> <b***>
OUTPUT <name^>

* int | ** float | *** float between 0 and 1 | ^ string

Examples can be seen in RaytracerTest/input/

Explanation for parameters

The near plane is defined as:

  • The absolute distance along the negative z-axis n
  • The view frustrum left, right, top, bottom
  • The render resolution in x columns, y rows

The sphere has the following parameters (In order):

  • An identifiable name for the object name
  • Position (in 3d space) x, y, z
  • Scale (in 3d space) scl x, scl y, scl z
  • The colour of the object r, g, b
  • The ambient reflection constant Ka
  • The diffuse reflection constant Kd
  • The specular reflection constant Ks
  • The reflection constant Kr
  • The specular exponent n

The light has the following parameters (In order):

  • An identifiable name for the object name
  • Position (in 3d space) x, y, z
  • Light Intensity r, g, b

The background colour r, g, b
The ambient intensity r, g, b
The name of the output file name

names are limited to 20 characters, with no spaces. All parameters are separated by spaces. There are no brackets in the input file (they are to clarify what each type is each parameter).

The application will not render if:

  • You do not specify a near plane, resolution, or frustrum
  • You do not specify a background colour
  • You do not specify an ambient light intensity

The executable is compiled for Windows with Visual C++17 as specified in the requirements of the assignment.

** The Windows target platform was changed to 10.0.18362.0 and may or may not work with VS 17**

Licenses

The project itself is licensed under GPLv3 and makes use of: