jtracer is a C++ path tracer capable of running either on the CPU (multithreaded or non-multithreaded) or as an Apple Metal compute kernel.
The path tracer was originally based on the implementation guide given by Peter Shirley's excellent ebook Ray Tracing In One Weekend. The algorithms were modified to make the them non-allocating (i.e. non stack based) by using color/light accumulators with a single ray object to trace through the scene.
The implementation found in jtracer/Trace is designed to be extremely portable. It is a header-only implementation of a general GPU-compute compatible tracer from a per-pixel standpoint given a set of scene parameters (in this case, a bunch of spheres). In theory, it should work in an OpenCL C++ or CUDA environment with little modification - likely just some system-specific definitions in JTTypes.h.
The frontend is written in Objective-C++. It is tested with Xcode 9.3 under macOS 10.13.4. The UI is extremely simple - all options are hardcoded within the app. On startup the main window will display two views: the top is a GPU-compute render via Metal, and the bottom is a multicore CPU render scheduled by libdispatch (Grand Central Dispatch). Below is a screenshot:
As with all hobby projects, jtracer is an ongoing effort and the main limitation is time. There is still an incredible amount of work to be done to make it useful for something more than a toy for myself, for example:
- Add refractions for objects with translucent materials.
- Add definitions for common materials (i.e. metal types) to allow physically-modeled IOR based on scientific measurements (i.e. for materials with nonlinear reflection response based on light intensity, which are most materials.)
- Model fresnel using the above material-based IOR.
- Allow for shapes other than spheres, i.e. polygons.
- Allow texturing of the above shapes.
- Add camera controls and effects such as motion blur, DOF, mouse interaction, etc.