About using filters and masks with shapes
You can apply filters to individual shapes or to a group that contains a number of shapes. You can use filters to stylize shapes far beyond the options available in the Shape Inspector. When you apply a filter to a shape, the shape remains editable. For more information, see Filters overview.
Important: After you apply a filter to a shape, you can no longer smoothly increase the size of that shape using the object’s transform controls. This is because filters change shapes from vector objects to bitmapped objects. As a result, they scale like other bitmapped objects, which display artifacts if they’re enlarged too much.
Use the mask-drawing tools in the toolbar to create masks that punch holes inside shapes. You can also apply an image mask to a shape, using another layer in Motion to define areas of transparency. For more information on using masks and image masks, see Masks and transparency overview.
Important: Some operations, as well the application of some filters or a mask, cause a group to be rasterized. When a group is rasterized, it’s converted into a bitmap image. Because all shape layers (masks, shapes, and paint strokes) are contained in groups, this affects how shapes interact with other objects in your project. For more information, see Shapes and rasterization.