added single shader validation

colorbleed/plugins/maya/publish/validate_look_single_shader.py

@@ -0,0 +1,61 @@
+from maya import cmds
+
+import pyblish.api
+import colorbleed.api
+
+
+class ValidateSingleShader(pyblish.api.InstancePlugin):
+    """Validate default shaders in the scene have their default connections.
+
+    For example the lambert1 could potentially be disconnected from the
+    initialShadingGroup. As such it's not lambert1 that will be identified
+    as the default shader which can have unpredictable results.
+
+    To fix the default connections need to be made again. See the logs for
+    more details on which connections are missing.
+
+    """
+
+    order = colorbleed.api.ValidateContentsOrder
+    families = ['colorbleed.lookdev']
+    hosts = ['maya']
+    label = 'Look Single Shader Per Shape'
+
+    # The default connections to check
+    def process(self, instance):
+
+        invalid = self.get_invalid(instance)
+        if invalid:
+            raise RuntimeError("Found shapes which have multiple "
+                               "shadingEngines connected."
+                               "\n{}".format(invalid))
+
+    @classmethod
+    def get_invalid(cls, instance):
+        invalid = []
+        shape_types = ["numrbsCurve", "nurbsSurface", "mesh"]
+
+        # Get all shapes from the instance
+        shapes = set()
+        for node in instance[:]:
+
+            nodetype = cmds.nodeType(node)
+            if nodetype in shape_types:
+                shapes.add(node)
+
+            elif nodetype == "transform":
+                shape = cmds.listRelatives(node, children=True,
+                                           type="shape", fullPath=True)
+                if not shape:
+                    continue
+                shapes.add(shape[0])
+
+        # Check the number of connected shadingEngines per shape
+        for shape in shapes:
+            shading_engines = cmds.listConnections(shape,
+                                                   destination=True,
+                                                   type="shadingEngine")
+            if len(shading_engines) > 1:
+                invalid.append(shape)
+
+        return invalid