Pablo Delgado

Implemented some basic 'primvar analysis' in Gatling. The idea is to detect patterns in secondary primvars (not part of vertex layout) and modify data & interpolation. For now, just checking for constant values, which is surprisingly effective for some assets.

Currently implementing Gaussian splatting in guc (glTF to USD converter) so that it can be released as soon as the extension comes out of RC status.

This weekend I added support for the MaterialX <time> and <frame> nodes to Gatling. Procedural materials can now be animated over time, such as this clock authored by Roberto Ziche:

Finally finished Gatling's Metal backend! Here's a teaser of NVIDIA's USD / MDL sample scene 'Attic' running on macOS. What's special about the backend is probably that it uses the same GLSL code as the Vulkan backend, complete with hardware ray tracing. How does that work?

As these functions don't have access to intrinsics, we need to pass them along as part of their signature. Which the function tables are parameterized with. Here's an example of how the ray generation shader signature ends up looking with two ray payloads:

Finally finished Gatling's Metal backend! Here's a teaser of NVIDIA's USD / MDL sample scene 'Attic' running on macOS. What's special about the backend is probably that it uses the same GLSL code as the Vulkan backend, complete with hardware ray tracing. How does that work?

An important difference between the graphics APIs is that Metal only has 'intersection' shaders that are invoked for non-opaque geometry. This is what I map any-hit shaders to. Their function addresses are stored in an intersection function table (IFT), similar to an SBT.

Finally finished Gatling's Metal backend! Here's a teaser of NVIDIA's USD / MDL sample scene 'Attic' running on macOS. What's special about the backend is probably that it uses the same GLSL code as the Vulkan backend, complete with hardware ray tracing. How does that work?

Spent some time this weekend updating Gatling’s Blender integration to the latest 5.0 release.

There are still some minor issues to resolve, including getting rid of static state (for multiple viewports) and implementing support for orthographic cameras.

Btw, a few weeks ago I released a small plugin for usdview. It allows inspection of UsdShade networks using a custom Qt node graph. It’s open source, lightweight and simple to install.

Small weekend experiment: ported an LCD shader from Blender to #MaterialX (originally authored by PixlFX)

Implemented USD point instancer primvar support in my toy renderer the last few days. Can now render this 2D Gaussian Splatting (2DGS) scene with a single mesh & MaterialX material. (Created by Oliver Markowski with Houdini, link see below ⬇️)

Made good progress with gatling lately, and one of the new features is graphical tests. They primarily run on GitHub Actions using Mesa lavapipe (supports ray tracing). Thresholds are specified as USD render settings, diff images are uploaded as artifacts (1/4)

To reduce the memory footprint, I first run the geometry through meshoptimizer which culls and deduplicates vertices. Next, the data is compressed with blosc. The results are quite good. Decompression only happens when a BLAS is rebuilt. (3/4)

Made good progress with gatling lately, and one of the new features is graphical tests. They primarily run on GitHub Actions using Mesa lavapipe (supports ray tracing). Thresholds are specified as USD render settings, diff images are uploaded as artifacts (1/4)