Is there a way to have both OpenGL viewport and Vulcan viewport open in one session or at least switch between them without restarting and changing env variables?

Thank you

Is there any difference between using Vulcan and OpenGL? I compared them and didn't notice significant differences in both appearance and performance; they both seem very similar to OpenGL.

EP nineteenma
Is there any difference between using Vulcan and OpenGL? I compared them and didn't notice significant differences in both appearance and performance; they both seem very similar to OpenGL.

They're supposed to look same, otherwise te Vulcan has failed. I believe Vulcan viewport at its current state is just SideFX trying to make a more robust, future-proof fundation for more advanced viewport features in later versions, but not something that you can just switch to and magically gain 200% performance.

I don't recall what are the visible differences, but try lots of (condensed) feathers.

How does Nvidia Studio drivers affect Vulkan?

OpenGL vs. Vulkan: What are the Key Differences? [history-computer.com]

LukeP
Is there a way to have both OpenGL viewport and Vulcan viewport open in one session or at least switch between them without restarting and changing env variables?

No, Houdini is either entirely in Vulkan or OpenGL mode. You can have two separate Houdini sessions running OpenGL and Vulkan from different shells, though.

EP nineteenma
Is there any difference between using Vulcan and OpenGL? I compared them and didn't notice significant differences in both appearance and performance; they both seem very similar to OpenGL.

There are some incremental improvements in rendering look, but that wasn't the focus for H20. Our primary goal was feature parity with OpenGL. The main reasons that Vulkan isn't exposed by default in H20 is that performance is not where we want it to be, and there are still a few missing pieces (mostly minor, but shadows are one of the more glaring missing features).

Anyway, the few imaging improvements we have are:

• Heightfields now draw in wireframe mode
  
• Lit Spheres particle mode is now perspective correct (also fixed in GL)
  
• Subdivision ribbons (aka hair) no longer has cracks between subd segments (also fixed in GL)
  
• Feathers look much nicer and render faster in Vulkan
  
• Lighting is always done with the deferred renderer now, which is generally more accurate (HQ Lighting in GL). This is still very much a work-in-progress in H20.
  

raincole
They're supposed to look same, otherwise te Vulcan has failed. I believe Vulcan viewport at its current state is just SideFX trying to make a more robust, future-proof fundation for more advanced viewport features in later versions, but not something that you can just switch to and magically gain 200% performance.

Well said, that's very much how we see it. Vulkan really helps in cases where there is a lot of unique geometry to be displayed, like a very large scene without much instancing use. It's much less CPU-intensive that OpenGL when issuing draw calls, and once we thread the viewport updates and renders, these scenes should see a decent performance boost. We are also taking the opportunity to reevaluate some of the ways we've been rendering certain elements and improving the shaders for those, which is independent of the API. There's still some outstanding work to be done there, especially for polysurfaces, so Vulkan will gradually overtake GL as that work is completed.

At the end of the day, your GPU hardware hasn't changed, so anything that was GPU bound before (instancing millions of cubes, for example) will remain GPU bound in Vulkan.

Werner Ziemerink
How does Nvidia Studio drivers affect Vulkan?

You need at least Nvidia 470 on Linux or 473 on Windows, both of which are far below our recommended version of 535 (for Karma XPU). Later versions add more Vulkan extensions, but unlike OpenGL and DirectX drivers, the Vulkan driver is very thin. Optimization is the developer's problem, not the driver's. So there's very little improvement, performance-wise, in different driver versions. The exception might be a Vulkan extension that enables us to use a more performant approach to rendering.