Added poll() function to fix crash with no selected objects. Grouped registration functions.

object_cloud_gen.py

@@ -20,7 +20,7 @@
 bl_addon_info = {
     'name': 'Object: Cloud Generator',
     'author': 'Nick Keeline(nrk)',
-    'version': '0.5',
+    'version': '0.6',
     'blender': (2, 5, 3),
     'location': 'Tool Shelf ',
     'description': 'Creates Volumetric Clouds',
@@ -41,6 +41,7 @@ Rev 0.2 Added Point Density turbulence and fixed degenerate
 Rev 0.3 Fixed bug in degenerate
 Rev 0.4 updated for api change/changed to new apply modifier technique
 Rev 0.5 made particle count equation with radius so radius increases with cloud volume
+Rev 0.6 added poll function to operator, fixing crash with no selected objects
 """
 
 import bpy
@@ -48,9 +49,6 @@ import mathutils
 from math import *
 from bpy.props import *
 
-# Deselect All
-bpy.ops.object.select_all(action='DESELECT')
-
 
 # This routine takes an object and deletes all of the geometry in it
 # and adds a bounding box to it.
@@ -281,23 +279,6 @@ class VIEW3D_PT_tools_cloud(View3DPanel):
             col.label(text="a cloud.")
         # col.label(active_obj["CloudMember"])
 
-classes = [VIEW3D_PT_tools_cloud]
-
-
-def register():
-    register = bpy.types.register
-    for cls in classes:
-        register(cls)
-
-
-def unregister():
-    unregister = bpy.types.unregister
-    for cls in classes:
-        unregister(cls)
-
-if __name__ == "__main__":
-    register()
-
 
 class GenerateCloud(bpy.types.Operator):
     bl_idname = "cloud.generate_cloud"
@@ -306,6 +287,12 @@ class GenerateCloud(bpy.types.Operator):
     bl_register = True
     bl_undo = True
 
+    def poll(self, context):
+        if not context.active_object:
+            return False
+        else:
+            return (context.active_object.type=='MESH')
+
     def execute(self, context):
         # Make variable that is the current .blend file main data blocks
         main = context.main
@@ -316,7 +303,6 @@ class GenerateCloud(bpy.types.Operator):
         # Make variable scene that is current scene
         scene = context.scene
 
-        if active_object and active_object.type == 'MESH':
         # Parameters the user may want to change:
         # Number of points this number is multiplied by the volume to get
         # the number of points the scripts will put in the volume.
@@ -330,7 +316,6 @@ class GenerateCloud(bpy.types.Operator):
         degenerate = degenerateCloud(active_object)
 
         if degenerate:
-                if active_object is not None:
            # Degenerate Cloud
            mainObj = active_object
 
@@ -390,14 +375,10 @@ class GenerateCloud(bpy.types.Operator):
             ###############Create Combined Object bounds##################
             # Make a list of all Selected objects.
             selectedObjects = bpy.context.selected_objects
+            if not selectedObjects:
+                selectedObjects = [bpy.context.active_object]
 
             # Create a new object bounds
-                if selectedObjects is None:
-                    bounds = addNewObject(scene,
-                        "CloudBounds",
-                        [])
-
-                else:
             bounds = addNewObject(scene,
                     "CloudBounds",
                     selectedObjects[0])
@@ -628,11 +609,25 @@ class GenerateCloud(bpy.types.Operator):
             #    scene.update()
             #bpy.ops.ptcache.bake_all(bake=False)
 
-            #self.report({'WARNING'}, "Generating Cloud")
 
         return {'FINISHED'}
 
-bpy.types.register(GenerateCloud)
+
+classes = [VIEW3D_PT_tools_cloud,
+        GenerateCloud]
+
+
+def register():
+    register = bpy.types.register
+    for cls in classes:
+        register(cls)
+
+
+def unregister():
+    unregister = bpy.types.unregister
+    for cls in classes:
+        unregister(cls)
+
 
 if __name__ == "__main__":
-    bpy.ops.cloud.generate_cloud()
+    register()