ShaderUI, ArnoldShaderUI : Allow nodeGadget:color to be specified

This allows the colour of the node in the GraphEditor to be customised on a per-shader basis.

Changes.md

@@ -20,6 +20,8 @@ Fixes
 API
 ---
 
+- ShaderUI : Added support for `nodeGadget:color` metadata registered against `{shaderType}:{shaderName}`, to specify per-shader colouring of nodes in the GraphEditor.
+- ArnoldShaderUI : Added support for `gaffer.nodeGadget.color` RGB metadata in `.mtd` files, to specify per-shader colouring of nodes in the GraphEditor.
 - Loop : Added `nextIterationContext()` method.
 
 API

python/GafferArnoldUI/ArnoldShaderUI.py

@@ -231,6 +231,15 @@ def __translateNodeMetadata( nodeEntry ) :
 	if iconScale is not None :
 		__metadata[nodeName]["iconScale"] = iconScale
 
+	# Node color.
+
+	color = __aiMetadataGetRGB( nodeEntry, None, "gaffer.nodeGadget.color" )
+	if color is not None :
+		Gaffer.Metadata.registerValue( "ai:surface:{}".format( nodeName ), "nodeGadget:color", color )
+
+	# Parameters
+	# ----------
+
 	paramIt = arnold.AiNodeEntryGetParamIterator( nodeEntry )
 	while not arnold.AiParamIteratorFinished( paramIt ) :
 

python/GafferSceneUI/ShaderUI.py

@@ -56,6 +56,12 @@
 # Metadata
 ##########################################################################
 
+def __shaderMetadata( node, key ) :
+
+	return Gaffer.Metadata.value(
+		node["type"].getValue() + ":" + node["name"].getValue(), key
+	)
+
 def __parameterUserDefault( plug ) :
 
 	shader = plug.node()
@@ -75,6 +81,7 @@ def __parameterUserDefault( plug ) :
 	""",
 
 	"nodeGadget:minWidth", 0.0,
+	"nodeGadget:color", functools.partial( __shaderMetadata, key = "nodeGadget:color" ),
 
 	plugs = {