Simplifying Your Life as a Blender Modeler with Modifiers
Blender has a feature, called modifiers, that helps tackle the monotony of working with complex models. Despite their rather generic-sounding name, modifiers are an extremely powerful way to save you time and frustration by letting the computer assume the responsibility for grunt work, such as adding smoothing vertices or making your model symmetric.
Another benefit of modifiers is that they’re nondestructive, meaning that you can freely add and remove modifiers to and from your object. As long as you don’t apply the modifier, it won’t actually make any permanent changes to the object itself. You can always return to the original, unmodified mesh.
You can access modifiers for your mesh in the Modifiers section of the Properties editor (its button has an icon of a blue wrench). Left-click the Add Modifier button to see a list of the modifiers that are available. The figure shows the Modifiers section with the list of available modifiers for meshes.
All Blender’s modifiers share some of the same controls between them. The next figure shows the Modifiers section with two modifiers added, Array and Bevel.
The first thing to notice is that the modifiers are stacked one below the other. This stacking is by design. What’s more, the order in which the modifiers appear in the stack is important because one modifier feeds into the next one. So the second modifier — Bevel, in this case — doesn’t operate on the original mesh data. Bevel actually operates on the new mesh data provided by the first modifier, Array, in this example.
The stacking order for modifiers is a little bit counter-intuitive if you think about it in terms of layers, where one builds on top of another. Blender’s modifier stack doesn’t work like that. Instead, you’re better off thinking of Blender’s modifier stack as a snowball rolling down a hill. Each modifier you hit on the way down the hill adds something or changes something about your snowball, modifying it more and more as it comes to the base of the hill.
The topmost modifier is the first modifier and operates on the original mesh data. The modifier immediately below it works on the data that comes from the first modifier, and so on down the line.
In the preceding example, the object is first made into an array. Then the mesh that is created by the Array modifier has its edges beveled so that they’re not as sharp-cornered. You can change the stacking order by using the up/down arrow buttons on the right side of each modifier block. Left-clicking the up arrow raises a modifier in the stack (bringing it closer to being first), whereas the down arrow lowers it.
You can left-click the X at the top right of any block to remove the modifier altogether. The downward triangle that’s to the left of each modifier’s name collapses and expands that modifier block when you left-click it. Collapsing the modifier block is useful for hiding a modifier’s controls after you’ve decided upon the settings you want to use.
Between the modifier name field and the stacking order buttons are three or four additional buttons, depending on whether your selected object is in Edit mode. From left to right, the first three buttons control whether the modifier is enabled for rendering (camera icon), viewing in Object mode (eye icon), and viewing in Edit mode (editing cube icon).
You may be wondering why you’d ever want to disable a modifier after you’ve added it to the stack, instead of just removing it and adding it back in later. The main reason is that many modifiers have an extensive set of options available to them. You may want to see how your object renders with and without the modifier to decide whether you want to use it.
You may want to edit your original mesh without seeing any of the changes made by the modifier. If you have a slow computer (or if you want your fast computer to be as responsive as possible), you want to have the modifier enabled only when rendering so that you can still work effectively without your computer choking on all the data coming from Blender.
Some modifiers, like Array, have an additional fourth button with an inverted triangle icon at the end of the button block. Its tooltip says that enabling this button will Adjust Edit Cage to Modifier Result. The edit cage is the input mesh, prior to any influence by the modifier. Enabling this button means that not only are the effects of the modifier visible in Edit mode, but you can also select and perform limited changes to the geometry created by the modifier.
Only two more buttons are common among all modifiers: the Apply and Copy buttons. Left-clicking the Apply button takes the changes made by the modifier and directly applies them to the original object. Applying actually creates the additional vertices and edges in the original mesh to make the mesh match the results produced by the modifier and then removes the modifier from the stack. While modifiers are nondestructive, meaning that they don’t permanently change the original object, the Apply button is the one exception.
The Apply button works only if the object you’re working on is in Object mode.
The Copy button creates a duplicate version of the modifier and adds it to the stack after the modifier you’re duplicating. You probably won’t be using this function very often, but it’s useful when you need to double up a modifier, such as if you want to use one Subdivision Surface modifier with simple subdivisions to get more raw geometry and then use a second Subdivision Surface modifier to smooth or curve that geometry.