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

requirement (Environment on my computer)：

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

How to Build:

• 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).

Difference from the paper-version code:

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.