From c21709bf619de25b0efd9dfd6da4b00f33f26199 Mon Sep 17 00:00:00 2001
From: Eric Mehl <eric@thinkhypothetical.com>
Date: Thu, 10 Aug 2023 11:50:06 -0400
Subject: [PATCH] LightFilterVisualiser : Support USD lights

---
 Changes.md                                            | 10 ++++++++++
 .../IECoreGLPreview/LightFilterVisualiser.cpp         | 11 +++++++++++
 2 files changed, 21 insertions(+)

diff --git a/Changes.md b/Changes.md
index e198a3adffd..fda94fccdfc 100644
--- a/Changes.md
+++ b/Changes.md
@@ -1,6 +1,16 @@
 1.3.x.x (relative to 1.3.1.0)
 =======
 
+Improvements
+------------
+
+- Viewer : Added visualisation of light filters for USD lights.
+
+Fixes
+-----
+
+- Viewer : Fixed crash when visualising lights with a light filter intended for a different renderer.
+
 
 1.3.1.0 (relative to 1.3.0.0)
 =======
diff --git a/src/GafferScene/IECoreGLPreview/LightFilterVisualiser.cpp b/src/GafferScene/IECoreGLPreview/LightFilterVisualiser.cpp
index 14ac8e438b5..e048251b0e0 100644
--- a/src/GafferScene/IECoreGLPreview/LightFilterVisualiser.cpp
+++ b/src/GafferScene/IECoreGLPreview/LightFilterVisualiser.cpp
@@ -132,6 +132,17 @@ Visualisations LightFilterVisualiser::allVisualisations( const IECore::CompoundO
 		boost::split( tokens, attributeName, boost::is_any_of(":") );
 		const IECoreScene::ShaderNetwork *lightShaderNetwork = attributes->member<IECoreScene::ShaderNetwork>( tokens.front() + ":light" );
 
+		// If the light is a USD light, the renderer-specific `lightShaderNetwork` won't be valid
+		if( !lightShaderNetwork )
+		{
+			lightShaderNetwork = attributes->member<IECoreScene::ShaderNetwork>( "light" );
+		}
+
+		if( !lightShaderNetwork )
+		{
+			continue;
+		}
+
 		// It's possible that we found a light filter defined in world space
 		// that isn't assigned to a light just yet. If we found a filter in
 		// light space it must have a valid light shader, though.