An OptiX 7 implementation of [SPCBPT: Subspace-based Probabilistic Connections for Bidirectional Path Tracing](SPCBPT (ssufujia.github.io)).

• OptiX 7.5.0
• Cuda 11.7
• Visual Studio 2019
• Cmake 3.24.2

• Start up cmake-gui from the Start Menu.
• Select the "src" directory and the source code
• Create a build directory that isn't the same as the source directory.
• Press "Configure" button and select the version of Visual Studio 2019.
• Select "x64" as the platform
• Press "OK".
• Set OptiX_INSTALL_DIR to wherever you installed OptiX, e.g., C:\ProgramData\NVIDIA Corporation\OptiX SDK 7.5.0
• Press "Configure" button again.
• Press "generate" and then "open Project"
• Right click the optixPathTracer project and set it as Startup project and run the renderer program (in Release).

Due to various reasons, some details of this implementation are slightly different from the paper-version code.

• This implementation disables the t = 1 strategy, i.e., the strategy of light sub-path connecting to the eye sub-path directly, because it is usually of low efficiency.
• The parts of cross-iteration reuse of light sub-path, environment map, and transparent material are not yet completed, I plan to implement them in the future update.
• Direction is ignored in the classification. Position and normal are more important in most cases.
• Subspace Sampling Matrix is trained from an initial matrix built from the full contribution integral of the paths in the corresponding subspace pair to speed up the training.
• Paths for training are traced by a simple unidirectional path tracer with NEE implementation.
• The over-bright fireflies are slightly more than my paper-version code, I would try to figure out and solve this problem in the future.