There are a few other ways to select polygons that can be very useful at times:

• "Include Group..." can be used to add the selection in another group to the current group.
• "Remove Group..." can be used to subtract the selection in another group from the current group (as was illustrated on Page 9).
• "Include Material..." can be used to add the polygons in a particular material to the current group.

Since we have already seen how "Remove Group..." works, I will not cover it again here. "Include Group..." and "Include Material..." are very similar, the main difference being the source of the polygons to be added. For that reason, I will only cover "Include Material...":

1. Re-open the Group Edit window and click "New Group" to create an empty group. Name the group "material_2" (or something else if you like). If you need a refresher on how to do this part, see Page 4.
2. Click "Include Material...". A dialog will appear with a popup menu of all the materials assigned to the ball. Select the material you created on Page 13. In my case, the material is also named "material_2" (but the names do not have to be the same).
3. Click "OK". You should now have the group "material_2" selected as your current group, and it will include all of the polygons assigned to the material named "material_2".
4. For the purposes of this tutorial, once you are finished having fun observing this phenomenon, make sure material_2 is selected as the current group and click "Delete Group". Having this extra group around would mess up some of the following steps.