Fix T103354: Author extents on UsdGeomMesh #104676

Michael B Johnson · 2023-02-13T02:32:48+01:00

Michael B Johnson commented

2023-02-13 02:32:48 +01:00

A properly authored USD file will have the extent attribute authored on all prims conforming to UsdGeomBoundable.
This cached extent information is useful because it allows the 3D range of prims to be quickly understood without reading potentially large arrays of data. Note that because the shape of prims may change over time, extent attributes are always evaluated for a given timecode.

This patch introduces support for authoring extents on meshes and volumes during export to USD.

Because extents are common to multiple kinds of geometries, the main support for authoring extents has been placed in USDAbstractWriter, whose new author_extent method can operate on any prim conforming to pxr::UsdGeomBoundable. The USD library already provides us the code necessary to compute the bounds for a given prim, in pxr::UsdGeomBBoxCache::ComputeLocalBound.
Note that not all prims that are imageable are boundable, such as transforms and cameras.

For more details on extents, see https://graphics.pixar.com/usd/release/api/class_usd_geom_boundable.html#details.

Note that when new types of geometries are introduced, such as curves in https://developer.blender.org/D16545, we will need to update the USD writer for that geometry such that it calls this->author_extent.

Update on Feb 2: This patch has been updated to include a unit test to ensure authored extents are valid. This test requires new test assets that will need to be submitted via svn. The test assets are attached in the d16837_usd_test_assets.zip file. To use, unzip and merge the contents of this zip into the lib/tests/usd folder.

This unit test also addresses #104269 by validating compliance of exported USD via UsdUtils.ComplianceChecker.

A properly authored USD file will have the extent attribute authored on all prims conforming to UsdGeomBoundable. This cached extent information is useful because it allows the 3D range of prims to be quickly understood without reading potentially large arrays of data. Note that because the shape of prims may change over time, extent attributes are always evaluated for a given timecode. This patch introduces support for authoring extents on meshes and volumes during export to USD. Because extents are common to multiple kinds of geometries, the main support for authoring extents has been placed in USDAbstractWriter, whose new author_extent method can operate on any prim conforming to pxr::UsdGeomBoundable. The USD library already provides us the code necessary to compute the bounds for a given prim, in pxr::UsdGeomBBoxCache::ComputeLocalBound. Note that not all prims that are imageable are boundable, such as transforms and cameras. For more details on extents, see https://graphics.pixar.com/usd/release/api/class_usd_geom_boundable.html#details. Note that when new types of geometries are introduced, such as curves in https://developer.blender.org/D16545, we will need to update the USD writer for that geometry such that it calls this->author_extent. Update on Feb 2: This patch has been updated to include a unit test to ensure authored extents are valid. This test requires new test assets that will need to be submitted via svn. The test assets are attached in the d16837_usd_test_assets.zip file. To use, unzip and merge the contents of this zip into the lib/tests/usd folder. This unit test also addresses #104269 by validating compliance of exported USD via UsdUtils.ComplianceChecker.

d16837_usd_test_assets.zip

142 KiB

Michael B Johnson added 4 commits 2023-02-13 02:34:03 +01:00

67136bfcfe Fix T103354: Author extents on UsdGeomMesh

* Author extent attribute on all meshes
* Move extent authoring to USDAbstractWriter, add support for hair and volumes

Code review changes: use Blender's own bounds cache for meshes

be1c115617 Update to comments as requested by Sybren

a60f0ec2c8 Add USD Export Python Test

Initial test uses USD Compliance Checker to validate an exported USD file. Test includes the ability to skip certain tests if so desired.

Requires https://developer.blender.org/D17041 to be merged before it will succeed.

The test asset used does not cover https://developer.blender.org/D17072 as we'll need to craft a test asset for that, and we need to work through that process first. I don't think that should hold up this CI test being integrated, since it wouldn't change the test itself.

5089928eb0 Add unit test for authoring extent. Also apply additional formatting changes suggested during review.

Requires the following new files:
lib/tests/usd/usd_extent_test.blend
lib/tests/usd/textures/small_cloud.vdb

Michael B Johnson changed title from ~~WIP contribs/T103354_author_extents~~ to Fix T103354: Author extents on UsdGeomMesh

2023-02-13 02:35:43 +01:00

Michael B Johnson requested review from Sybren A. Stüvel 2023-02-13 02:38:54 +01:00

Michael B Johnson requested review from Michael Kowalski 2023-02-13 02:39:00 +01:00

Michael B Johnson requested review from Bastien Montagne 2023-02-13 02:40:49 +01:00

Brecht Van Lommel added this to the USD project 2023-02-13 09:06:47 +01:00

Sybren A. Stüvel added the

 @ -152,0 +162,4 @@
   pxr::GfBBox3d bounds = bboxCache.ComputeLocalBound(prim.GetPrim());
   if (pxr::GfBBox3d() == bounds) {
     /* This will occur, for example, if a mesh does not have any vertices. */
     WM_reportf(RPT_ERROR,

 @ -0,0 +15,4 @@
 args = None
 class Result(str, enum.Enum):

 @ -0,0 +61,4 @@
         )
         checker.CheckCompliance(str(export_path))
         collection = {}

 @ -0,0 +63,4 @@
         collection = {}
         to_skip = ("MissingReferenceChecker",)

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Fix T103354: Author extents on UsdGeomMesh #104676