Good afternoon, I am a newbie with OptiX but trying to learn. Please forgive if this is a dumb question. Is there a way to control the total number of rays generated by OptiX during rendering programmatically? I would like to run some low-level performance studies for rendering by increasing/decre…

Hey there @rhaney , with OptiX you always have complete control over exactly how many rays you trace, and what the rays do when you trace them. With OptiX 7, for example, you always trace a ray explicitly using a call to the function optixTrace(). If you call optixTrace exactly once in your raygen pr…

Thank you @dhart and @droettger . Good information for a newbie to OptiX.

Another newbie question, different subject, if that is okay. I ran the Siggraph OptiX 7 example2_pipelineAndRayGen on a RT and non-RT card separately to get an idea of performance for different cards. I noticed that for smaller frame sizes the non-RT card outperformed the RT card but once the frame…

That would need some more details about the system configurations you’ve been comparing. That example2_pipelineAndRayGen is just filling the output buffer without shooting a single ray. https://gitlab.com/ingowald/optix7course/-/blob/master/example02_pipelineAndRayGen/devicePrograms.cu#L64 That’s…

Thank you @droettger for information. Dumb question but are there any example(s) with OptiX 7 that render a single frame using ray tracing? Something that is fairly straightforward for a newbie? Thanks again.

Sure, just work through the OptIX SDK 7.0.0 or 7.1.0 examples and you’ll see. Look at the optixTriangle code which does everything in the main() function and either renders the image to the screen or writes it to disk. The only simpler example is optixHello which doesn’t even shoot a ray. This bl…

Thank you again @droettger . The links and information is very helpful. I will set the output file to some value (e.g. ‘triangle.ppm’) so a single image is written to disk and put a timer around the optixLaunch call in the main() function to get a execution time of ray tracing.

Actually since the optixLaunch() calls are asynchronous, you need to include the following cudaDeviceSynchronize() call as well (inside the CUDA_SYNC_CHECK macro) or you get only the time to submit the launch to CUDA, not the actual ray tracing performance. That example is not going to give you a …

@droettger got it. Thanks again.

Newbie OptiX question(s)

Gaming and Visualization Technologies Visualization OptiX

droettger July 17, 2020, 9:18am 3

Also answered here:
https://forums.developer.nvidia.com/t/optix-7-and-msvs-2017-hello-world-on-windows-10/141711/9

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