Support for matte in RenderPass

[cpichard]

Changes proposed in this pull request

• In hydra2, use the active render pass to filter matted objects
• Add kick -sceneload_arg render_pass /My/RenderPass/Path to pass the RenderPass prim path to use when rendering with kick

Issues fixed in this pull request
Fixes #2549

[Copilot]

Pull request overview

Adds hydra2 RenderPass matte support by propagating RenderPass “matte” membership into Arnold primvars, and introduces a kick sceneload argument to select the active RenderPass prim to use during rendering.

Changes:

• Apply RenderPass matte overrides in the render pass scene index (authoring arnold:matte primvar overrides).
• Add render_pass sceneload arg support (plumbed to hydra2 via HdsiSceneGlobalsSceneIndex).
• Add regression test coverage for matte in hydra2 render passes (#2549).

Reviewed changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
testsuite/test_2549/ref/reference.tif	New reference image for #2549 regression.
testsuite/test_2549/data/test.usda	New USD scene defining a RenderPass with a matte collection.
testsuite/test_2549/README	New test definition invoking kick with -scenoload_arg render_pass ....
plugins/scene_index/renderPassSIP.cpp	Implements matte override as arnold:matte primvar when active RenderPass says so.
plugins/procedural/main.cpp	Reads render_pass sceneload arg and forwards to the active reader.
libs/translator/reader/reader.h	Adds SetRenderPass override (currently a no-op) to satisfy new interface.
libs/render_delegate/reader.h	Declares SetRenderPass in hydra reader and adds SceneGlobals scene index member/include.
libs/render_delegate/reader.cpp	Implements SetRenderPass and inserts HdsiSceneGlobalsSceneIndex in scene index chain.
libs/common/procedural_reader.h	Extends ProceduralReader interface with SetRenderPass.
libs/common/constant_strings.h	Adds arnold:matte and render_pass string tokens.
CHANGELOG.md	Records the bug fix entry for #2549.

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[Copilot]

HdsiSceneGlobalsSceneIndexRefPtr appears to be a new type used here, but this header doesn’t declare it via TF_DECLARE_REF_PTRS(HdsiSceneGlobalsSceneIndex) (unlike other Hdsi types above). If the USD header doesn’t provide the typedef (and especially when ENABLE_SCENE_INDEX is off and the header isn’t included), this will be a compile error. Please add the corresponding TF_DECLARE_REF_PTRS declaration (or avoid the RefPtr typedef in this member).

[Copilot]

This test is configured with a single ref/reference.tif, but the testsuite runner executes every test in all enabled passes (usd/hydra/hydra2) and will diff each pass output against the reference unless you provide pass-specific references. Since the README states this only works in hydra2, consider adding pass-specific reference images (e.g. reference.hydra2.tif, plus a non-hydra2 reference if needed) or otherwise adjusting the test so it won’t fail in the usd/hydra passes.

Suggested change

	PARAMS: {'scene':'test.usda', 'kick_params': '-sceneload_arg render_pass /Render/Passes/renderpass2'}
	PARAMS: {'scene':'test.usda', 'kick_params': '-sceneload_arg render_pass /Render/Passes/renderpass2'}
	PASSES: hydra2

[Copilot]

HydraArnoldReader::SetRenderPass calls HdsiSceneGlobalsSceneIndex::SetActiveRenderPassPrimPath, but this function is not guarded by #ifdef ARNOLD_SCENE_INDEX. In SCons builds where BUILD_SCENE_INDEX_PLUGIN is false, ENABLE_SCENE_INDEX (and thus the Hdsi headers) aren’t available, so this will fail to compile. Consider wrapping the implementation in #ifdef ARNOLD_SCENE_INDEX (and TF_UNUSED(renderPass) in the #else) or including the required Hdsi header unconditionally when this method is compiled.

Suggested change

	void HydraArnoldReader::SetRenderPass(const std::string &renderPass) {
	if (_sceneGlobalsSceneIndex) {
	SdfPath renderPassPrimPath(renderPass);
	if (!renderPassPrimPath.IsEmpty()) {
	_sceneGlobalsSceneIndex->SetActiveRenderPassPrimPath(renderPassPrimPath);
	}
	}
	void HydraArnoldReader::SetRenderPass(const std::string &renderPass) {
	#ifdef ARNOLD_SCENE_INDEX
	if (_sceneGlobalsSceneIndex) {
	SdfPath renderPassPrimPath(renderPass);
	if (!renderPassPrimPath.IsEmpty()) {
	_sceneGlobalsSceneIndex->SetActiveRenderPassPrimPath(renderPassPrimPath);
	}
	}
	#else
	TF_UNUSED(renderPass);
	#endif