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RayEngine is a C++ rendering engine for CPU/GPU accelerated ray tracing utilizing Embree and OptiX. It was created for a Bachelor's Thesis in Computer Science, described here.

Running the program

RayEngine is for Windows only (64-bit) and requires a NVIDIA GPU to be able to launch. Click the green "Clone or download" button and "Download ZIP". The executable can be found in the "RayEngine" folder as "RayEngine.exe" after extracting. The following must also be installed:

Controls and settings

The camera is oriented by left clicking and moving the mouse around. While the left button is pressed, the following key commands become active:

  • W/S/A/D Move forward/back/left/right.
  • Q/E Roll the camera.
  • Space/Shift Speed up/Slow down movement.
  • T/G Increase/Decrease FOV (Field of View). The following key commands are also available:
  • F1 Show/Hide GUI.
  • F2 Start/Stop benchmarking.
  • F3 Save a HD screenshot into the renders/ folder.

The up/down arrow keys are used to navigate through the settings menu, while right/left will change the selected value. Here are short descriptions of the settings:

  • Scene Changes the current scene from the ones pre-loaded into memory.
  • Render mode Switches the render mode between OpenGL, Embree, OptiX and Hybrid.
  • Resolution Switches the window resolution between 800x600, 1280x720 and 1980x1080.
  • Camera path Sets the camera to follow a predetermined path, used for benchmarking.
  • Reflections Enables/Disables reflections in the scene.
  • Max reflections Sets the maximum number of recursive calls for reflections.
  • Refractions Enables/Disables refractions/transparent surfaces in the scene.
  • Max refractions Sets the maximum number of recursive calls for refractions/transparent surfaces.
  • Ambient Occlusion Enables/Disables ambient occlusion in the scene.
  • AO samples The amount of rays to send in a hemisphere around the intersection point. A larger value will give softer (less noisy) shades, but require more processing.
  • AO radius The radius of the sampling hemisphere.
  • AO power The power/strength of the ambient occlusion effect.
  • AO noise scale Determines the scale of the noise texture used when randomly sampling.
  • Embree threads Tells OpenMP how many threads to use when Embree is rendering, this value is used with omp_set_num_threads.
  • Embree tiles Enables/Disables tiles when Embree is rendering. If disabled, a single loop will be used.
  • Width/Height Determines the dimensions of the tiles. A value larger or equal to the packet size (8) is recommended to assure coherency.
  • Embree primary packets Packets (RTCRay8) will be used for all the primary rays.
  • Embree secondary packets Packets will be used for all the secondary rays (shadows, reflections, refractions, ambient occlusion). This setting has shown to give a slowdown.
  • OptiX progressive render If enabled, progressive rendering will be used by OptiX, i.e. the program will use a non-blocking launch call.
  • OptiX stack size Sets the size of the GPU stack. A small value will lead to distorted reflections and refractions.
  • Hybrid threaded The hybrid mode will use a threaded approach, where the master approach runs OptiX while the other runs Embree. After both threads have finished, the result will be fetched and rendered on the screen.
  • Hybrid balance mode Changes the Hybrid balancing mode, either manual or based on the render time.
  • Partition When the balance mode is manual, this setting will determine the amount of the screen to give to Embree and OptiX, respectively.
  • Hybrid Display Partition When enabled, the Embree and OptiX images will be highlighted blue and red.
  • Hybrid Enable Embree Enables/Disables Embree. Used for debugging purposes.
  • Hybrid Enable OptiX Enables/Disables OptiX. Used for debugging purposes.

Building the program

Currently only the Glass Scene is loaded, but other scenes can be enabled or built by editing the main.cpp file and recompiling. This requires C++ library knowledge. To build from source (Visual Studio), the following are needed:

After installing these requirements, make sure the Include and Library directories are correct in Project Properties of the Visual Studio solution and that the .exe can access the correct .dll files.


Rendering engine for CPU/GPU accelerated ray tracing






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