Allow previewing vertex lighting from lightmap mod.

This is the beginning of a workflow loop to (hopefully) improve the
performance of exporting Ages with expensive lighting. This commit
allows you to generate the autocolor layer in the Korman UI and rename
it to `col` to prevent needless re-baking.

korman/operators/op_lightmap.py

@@ -44,10 +44,14 @@ class LightmapAutobakePreviewOperator(_LightingOperator, bpy.types.Operator):
                     self.report({"INFO"}, "No valid lights found to bake.")
                     return {"FINISHED"}
 
+        if context.object.plasma_modifiers.lightmap.bake_type == "lightmap":
             tex = bpy.data.textures.get("LIGHTMAPGEN_PREVIEW")
             if tex is None:
                 tex = bpy.data.textures.new("LIGHTMAPGEN_PREVIEW", "IMAGE")
             tex.extension = "CLIP"
             tex.image = bpy.data.images["{}_LIGHTMAPGEN.png".format(context.active_object.name)]
+        else:
+            for i in context.object.data.vertex_colors:
+                i.active = i.name == "autocolor"
 
         return {"FINISHED"}

korman/ui/modifiers/render.py

@@ -202,13 +202,13 @@ def lightmap(modifier, layout, context):
         layout.label("Transparent objects cannot be lightmapped.", icon="ERROR")
     else:
         col = layout.column()
-        col.active = is_texture
-        operator = col.operator("object.plasma_lightmap_preview", "Preview Lightmap", icon="RENDER_STILL")
+        col.operator("object.plasma_lightmap_preview", "Preview Lightmap" if is_texture else "Preview Vertex Colors", icon="RENDER_STILL")
 
         # Kind of clever stuff to show the user a preview...
         # We can't show images, so we make a hidden ImageTexture called LIGHTMAPGEN_PREVIEW. We check
         # the backing image name to see if it's for this lightmap. If so, you have a preview. If not,
         # well... It was nice knowing you!
+        if is_texture:
             tex = bpy.data.textures.get("LIGHTMAPGEN_PREVIEW")
             if tex is not None and tex.image is not None:
                 im_name = "{}_LIGHTMAPGEN.png".format(context.active_object.name)