Cycles: Add OptiX AI denoiser support

This patch adds support for the OptiX denoiser as an alternative to the existing NLM denoiser in Cycles. It's re-using the same denoising architecture based on tiles and therefore implicitly also works with multiple GPUs.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D6395

intern/cycles/render/session.cpp

@@ -285,9 +285,7 @@ void Session::run_gpu()
 
       if (progress.get_cancel())
         break;
-    }
 
-    if (!no_tiles) {
       /* buffers mutex is locked entirely while rendering each
        * sample, and released/reacquired on each iteration to allow
        * reset and draw in between */
@@ -978,7 +976,7 @@ void Session::update_status_time(bool show_pause, bool show_done)
        */
       substatus += string_printf(", Sample %d/%d", progress.get_current_sample(), num_samples);
     }
-    if (params.full_denoising) {
+    if (params.full_denoising || params.optix_denoising) {
       substatus += string_printf(", Denoised %d tiles", progress.get_denoised_tiles());
     }
     else if (params.run_denoising) {
@@ -1038,6 +1036,7 @@ void Session::render()
 
     task.denoising_from_render = true;
     task.denoising_do_filter = params.full_denoising;
+    task.denoising_use_optix = params.optix_denoising;
     task.denoising_write_passes = params.write_denoising_passes;
   }