The sticky posts on this sub-forum contain links to more OptiX 7 examples than inside the SDK alone.
I’m not aware of an example showing custom intersection programs on any kind of higher order surfaces.
The OptiX 7 SDKs contain an example showing how to implement a custom intersection program for a sphere primitive. The older SDKs also showed that for triangles.
Be aware of your coordinate spaces! https://forums.developer.nvidia.com/t/objects-appearing-in-the-wrong-order-after-scaling/83884/7
I’m not sure what you mean with sphere tracing system. If you mean tracing rays through a signed distance field for example, like you normally do for ray marching, that would not actually require a ray tracer which is optimized for ray-surface intersections if there aren’t any geometric primitives inside your volume data as well.
Means since there are no real intersection results with geometric primitives when only ray marching through some volume, that could also be done more efficiently with native CUDA kernels instead of actually shooting rays with OptiX.
Please find similar discussions here:
https://forums.developer.nvidia.com/t/keeping-track-of-multiple-materials-at-a-time/78066
https://forums.developer.nvidia.com/t/best-practice-voxels-use-triangles-or-custom-geometry-for-calculations-not-rendering/115230
https://forums.developer.nvidia.com/t/optix-6-0-process-each-object-one-by-one/119698
https://forums.developer.nvidia.com/t/using-optix-to-determine-travel-time-for-a-ray-travelling-through-a-material/112772