InteractiveRender : Fix source of globals for resolvedRenderer

We were pulling on the adapted globals, which themselves could depend on `resolvedRenderer` via the `renderer` input to the adaptor.

Changes.md

@@ -30,6 +30,9 @@ Fixes
   - Fixed errors when the input image didn't contain the main `RGBA` channels.
   - Fixed inaccurate hash.
 - SceneAlgo : Fixed exception handling for Python render adaptors. Previously an exception during adaptor construction caused a `SystemError`.
+- InteractiveRender :
+  - Fixed crash triggered by a render adaptor depending on its `renderer` input to adapt the scene globals.
+  - Removed unintentional ability for render adaptors to change the renderer being used.
 
 API
 ---

python/GafferSceneTest/InteractiveRenderTest.py

@@ -2252,6 +2252,52 @@ def testResolvedRenderer( self ) :
 		render["renderer"].setValue( "Other" )
 		self.assertEqual( render["resolvedRenderer"].getValue(), "Other" )
 
+	def testAdaptorsCantChangeRenderer( self ) :
+
+		def adaptor() :
+
+			result = GafferScene.StandardOptions()
+			result["options"]["defaultRenderer"]["enabled"].setValue( True )
+			result["options"]["defaultRenderer"]["value"].setValue( "IAmNotAllowed" )
+			return result
+
+		GafferScene.SceneAlgo.registerRenderAdaptor( "Test", adaptor )
+
+		standardOptions = GafferScene.StandardOptions()
+		standardOptions["options"]["defaultRenderer"]["enabled"].setValue( True )
+		standardOptions["options"]["defaultRenderer"]["value"].setValue( self.renderer )
+
+		interactiveRender = GafferScene.InteractiveRender()
+		interactiveRender["in"].setInput( standardOptions["out"] )
+
+		self.assertEqual( interactiveRender["resolvedRenderer"].getValue(), self.renderer )
+
+	def testAdaptorGlobalsDependingOnRenderer( self ) :
+
+		def adaptor() :
+
+			result = GafferScene.SceneProcessor()
+			result["renderer"] = Gaffer.StringPlug()
+
+			result["__customOptions"] = GafferScene.CustomOptions()
+			result["__customOptions"]["options"].addChild( Gaffer.NameValuePlug( "test", Gaffer.StringPlug() ) )
+			result["__customOptions"]["options"][0]["value"].setInput( result["renderer"] )
+
+			result["out"].setInput( result["__customOptions"]["out"] )
+			return result
+
+		GafferScene.SceneAlgo.registerRenderAdaptor( "Test", adaptor )
+
+		standardOptions = GafferScene.StandardOptions()
+		standardOptions["options"]["defaultRenderer"]["enabled"].setValue( True )
+		standardOptions["options"]["defaultRenderer"]["value"].setValue( self.renderer )
+
+		interactiveRender = GafferScene.InteractiveRender()
+		interactiveRender["in"].setInput( standardOptions["out"] )
+
+		self.assertEqual( interactiveRender["resolvedRenderer"].getValue(), self.renderer )
+		self.assertEqual( interactiveRender["__adaptedIn"].globals()["option:test"], IECore.StringData( self.renderer ) )
+
 	def tearDown( self ) :
 
 		GafferSceneTest.SceneTestCase.tearDown( self )

src/GafferScene/InteractiveRender.cpp

@@ -516,7 +516,7 @@ void InteractiveRender::compute( Gaffer::ValuePlug *output, const Gaffer::Contex
 		std::string renderer = rendererPlug()->getValue();
 		if( renderer.empty() )
 		{
-			ConstCompoundObjectPtr globals = adaptedInPlug()->globals();
+			ConstCompoundObjectPtr globals = inPlug()->globals();
 			if( auto rendererData = globals->member<const StringData>( g_rendererOptionName ) )
 			{
 				renderer = rendererData->readable();