Using the Modifier Stack
After a modifier is applied, its parameters appear in rollouts within the Command Panel. The Modifier Stack rollout, shown in Figure 12.1, lists the base object and all the modifiers that have been applied to an object. Any new modifiers applied to an object are placed at the top of the stack. By selecting a modifier from the list in the Modifier Stack, all the parameters for that specific modifier are displayed in rollouts.
Figure 12.1: The Modifier Stack rollout displays all modifiers applied to an object.
| Tip | You can increase or decrease the size of the Modifier Stack by dragging the horizontal bar that appears beneath the Modifier Stack buttons. |
Beneath the Modifier Stack are five buttons that affect the selected modifier. They are as described in Table 12.1.
| CROSS-REF | For more information on configuring modifier sets, see Chapter 5, "Customizing the Max Interface and Setting Preferences." |
If you right-click on a modifier, a pop-up menu appears. This pop-up menu includes commands to rename the selected modifier, which you might want to do if the same modifier is applied to the same object multiple times. This pop-up menu also includes an option to delete the selected modifier among other commands.
| Button | Name | Description |
|---|---|---|
| | Pin Stack | Makes the parameters for the selected modifier available for editing even if another object is selected (like taking a physical pin and sticking it into the screen so it won't move). |
| | Show End Result On/Off Toggle | Shows the end results of all the modifiers in the entire Stack when enabled and only the modifiers up to the current selected modifier if disabled. |
| | Make Unique | Used to break any instance or reference links to the selected object. After you click this button, an object will no longer be modified along with the other objects for which it was an instance or reference. Works for Base Object and modifiers. |
| | Remove Modifier from the Stack | Used to delete a modifier from the Stack or unbind a Space Warp if one is selected. Deleting a modifier restores it to the same state it was in before the modifier was applied. |
| | Configure Modifier Sets | Opens a pop-up menu where you can select to show a set of modifiers as buttons above the Modifier Stack. You can also select which modifier set appears at the top of the list of modifiers. The pop-up menu also includes an option to configure and define the various sets of modifiers. |
Open table as spreadsheet 
Copying and pasting modifiers
The pop-up menu also includes options to Cut, Copy, Paste, and Paste Instance modifiers. The Cut command deletes the modifier from the current object but makes it available for pasting onto other objects. The Copy command retains the modifier for the current object and makes it available to paste onto another object. After you use the Cut or Copy command, you can use the Paste command to apply the modifier to another object. The Paste Instance command retains a link between the original modifier and the instanced modifier, so that any changes to either modifier affect the other instances.
You can also apply modifiers for the current object onto other objects by dragging the modifier from the Modifier Stack and dropping it on the other object in a viewport. Holding down the Ctrl key while dropping a modifier onto an object in a viewport applies the modifier as an instance (like the Paste Instance command). Holding down the Shift key while dragging and dropping a modifier on an object in the viewport removes the modifier from the current object and applies it to the object on which it is dropped (like the Cut and Paste commands).
| CROSS-REF | You also cut, copy, and paste modifiers using the Schematic View window. See Chapter 11, "Working with the Schematic View," for more details. |
Using instanced modifiers
When you apply a single modifier to several objects at the same time, the modifier shows up in the Modifier Stack for each object. These are instanced modifiers that maintain a connection to each other. If one of these instanced modifiers is changed, the change is propagated to all other instances. This feature is very helpful for modifying large groups of objects.
When a modifier is copied between different objects, you can select to make the copy an instance.
To see all the objects that are linked to a particular modifier, select an object in the viewport and choose Views 
Show Dependencies. All objects with instanced modifiers that are connected to the current selection appear in bright pink. At any time, you can break the link between a particular instanced modifier and the rest of the objects using the Make Unique button in the Modifier Stack rollout.
Identifying instances and references in the Modifier Stack
If you look closely at the Modifier Stack, you will notice that it includes some visual clues that help you identify instances and references. Regular object and modifier copies appear in normal text, but instances appear in bold. This applies to both objects and modifiers. If a modifier is applied to two or more objects, then it appears in italic.
Referenced objects and modifiers can be identified by a Reference Object Bar that splits the Modifier Stack into two categories-ones that are unique to the referenced object (above the bar) and ones that are shared with the other references (below the bar).
Figure 12.2 shows each of these cases in the Modifier Stack.
Figure 12.2: The Modifier Stack changes the text style to identify instances and references.
Disabling and removing modifiers
Clicking the light bulb icon to the left of the modifier name toggles the modifier on and off. The right-click pop-up menu also offers options to turn the modifier off in the viewport or off for the renderer.
To remove a modifier from the Modifier Stack, just select the modifier and press the Remove Modifier button below the stack. This button removes the selected modifier only. You can select multiple modifiers at once by holding down the Ctrl key while clicking individually on the modifiers or by holding down the Shift key and clicking on the first and last modifiers in a range.
Reordering the Stack
Modifiers are listed in the Modifier Stack with the first applied ones on the bottom and the newest applied ones on the top. The Stack order is important and can change the appearance of the object. Max applies the modifiers starting with the lowest one in the Stack first and the topmost modifier last. You can change the order of the modifiers in the Stack by selecting a modifier and dragging it above or below the other modifiers. You cannot drag it below the object type or above any World-Space modifiers or Space Warp bindings.
Tutorial: Creating a molecular chain
Whether you're working with DNA splices or creating an animation to show how molecular chains are formed, you can use the Lattice and Twist modifiers to quickly create a molecular chain. Using these chains shows how reordering the Modifier Stack can change the outcome.
To create a molecular chain using modifiers, follow these steps.
-
Select Create
Standard Primitives 
Plane, and drag in the Top viewport to create a Plane object. Set its Length to 300, its Width to 60, its Length Segments to 11, and its Width Segments to 1. -
With the Plane object selected, select Modifiers
Parametric Deformers 
Lattice to apply the Lattice modifier. Enable the Apply to Entire Object option. Then set the Struts Radius value to 1.0 with 12 sides and the Joints Base Type to Icosa with a Radius of 6.0 and a Segments value of 6. -
Select Modifiers
Parametric Deformers 
Twist, and set the Twist Angle to 360 about the Y-axis. -
Notice that the Sphere objects have been twisted along with the Plane object. You can fix this by switching the modifier order in the Modifier Stack. Select the Lattice modifier, and drag and drop it above the Twist modifier in the stack.
This step corrects the elongated spheres.
Figure 12.3 shows the corrected molecular chain.
Figure 12.3: Changing the order of the modifiers in the Stack can affect the end result.
Holding and fetching a scene
Before going any farther, you need to know about an important feature in Max that allows you to set a stopping point for the current scene. The Hold command saves the scene into a temporary buffer for easy recovery. After a scene is set with the Hold command (Alt+Ctrl+H), you can bring it back instantly with the Fetch command (Alt+Ctrl+F). These commands provide a quick way to backtrack on modifications to a scene or project without your having to save and reload the project. If you use these commands before applying or deleting modifiers, you can avoid some potential headaches.
| Tip | Along with saving your file often, using the Hold command before applying any complex modifier to an object is a good idea. |
Collapsing the Stack
Collapsing the Stack removes all its modifiers by permanently applying them to the object. It also resets the modification history to a baseline. All the individual modifiers in the Stack are combined into one single modification. This feature eliminates the ability to change any modifier parameters, but it simplifies the object. The right-click pop-up menu offers options to Collapse To and Collapse All. You can collapse the entire Stack with the Collapse All command, or you can collapse to the current selected modifier with the Collapse To command. Collapsed objects typically become Editable Mesh objects.
| Tip | Another huge advantage of collapsing the Modifier Stack is that it conserves memory and results in smaller file sizes, which makes larger scenes load much quicker. |
When you apply a collapse command, a warning dialog box appears, shown in Figure 12.4, notifying you that this action will delete all the creation parameters. Click Yes to continue with the collapse.
Figure 12.4: Because the Collapse operation cannot be undone, this warning dialog box offers a chance to Hold the scene.
| Note | In addition to the Yes and No buttons, the warning dialog box includes a Hold/Yes button. This button saves the current state of the object to the Hold buffer and then applies the Collapse All function. If you have any problems, you can retrieve the object's previous state before the collapse was applied by choosing Edit |
Using the Collapse utility
You can also use the Collapse utility found on the Utility panel to collapse the Modifier Stack. This utility enables you to collapse an object or several objects to a Modifier Stack Result or to a Mesh object. Collapsing to a Modifier Stack Result doesn't necessarily produce a mesh but collapses the object to its base object state, which is displayed at the bottom of the Stack hierarchy. Depending on the Stack, this could result in a mesh, patch, spline, or other object type. You can also collapse to a Single Object or to Multiple Objects.
If the Mesh and Single Object options are selected, you can also select to perform a Boolean operation. The Boolean operations are available if you are collapsing several overlapping objects into one. The options are Union (which combines geometries together), Intersection (which combines only the overlapping geometries), and Subtraction (which subtracts one geometry from another).
| CROSS-REF | Boolean operations can also be performed using the Boolean compound object. See Chapter 18, "Working with Compound Objects," for details on this object type. |
If multiple objects are selected, then a Boolean Intersection results in only the sections of the objects that are intersected by all objects; if no objects overlap, all objects disappear.
If you use the Boolean Subtraction option, you can specify which object is the base object from which the other objects are subtracted. To do so, select that object first and then select the other objects by holding down the Ctrl key and clicking them. Figure 12.5 shows an example of each of the Boolean operations.
Figure 12.5: Using the Collapse utility, you can select the following Boolean operations (shown from left to right): Union, Intersection, and Subtraction.
Using gizmo subobjects
As you've worked with modifiers, you've probably noticed the orange wireframe box that surrounds the object in the viewports when you apply the modifier. These boxes are called modifier gizmos, and they provide a visual control for how the modifier changes the geometry. If you want, you can work directly with these gizmos to affect the modifier.
Clicking the plus sign to the left of the modifier name reveals any subobjects associated with the modifier. To select the modifier subobjects, simply click the subobject name. The subobject name is highlighted in yellow when selected. Many modifiers create gizmo subobjects. Gizmos have an icon usually in the shape of a box that can be transformed and controlled like regular objects using the transformation buttons on the main toolbar. Another common modifier subobject is Center, which controls the point about which the gizmo is transformed.
Tutorial: Squeezing a plastic bottle
To get a feel for how the modifier gizmo and its center affect an object, this tutorial applies the Squeeze modifier to a plastic bottle; by moving its center, we can change the shape of the object.
To change a modifier's characteristics by moving its center, follow these steps:
-
Open the
Plastic bottle.max file from the Chap 12 directory on the DVD.This file includes a plastic squirt bottle with all the parts attached into a single mesh object.
-
With the bottle selected, choose the Modifiers
Parametric Deformers 
Squeeze menu command to apply the Squeeze modifier to the bottle. Set the Radial Squeeze Amount value to 1. -
In the Modifier Stack, click the plus sign to the left of the Squeeze modifier to see the modifier's subobjects. Select the Center subobject.
The selected subobject is highlighted in yellow.
-
Click the Select and Move (W) button on the main toolbar, and drag the center point in the Perspective viewport upward.
Notice how the bottle's shape changes.
Figure 12.6 shows several different bottle shapes created by moving the modifier's center point.
Figure 12.6: By changing the modifier's center point, the bottle's shape changes.
Modifying subobjects
In addition to being applied to complete objects, modifiers can also be applied and used to modify subobjects. A subobject is defined as a collection of object parts, such as vertices, edges, faces, or elements.
| CROSS-REF | To learn more about applying modifiers to subobject selections, see Chapter 13, "Learning Modeling Basics and Working with Subobjects." |
To work in subobject selection mode, click the plus sign to the left of the object name to see the subobjects. Several modifiers, including Mesh Select, Spline Select, and Volume Select, can select subobject areas for passing these selections up to the next modifier in the Stack. For example, you can use the Mesh Select modifier to select several faces on the front of a sphere and then apply the Face Extrude modifier to extrude just those faces.
Topology dependency
When you attempt to modify the parameters of a Base Object that has a modifier applied, you sometimes get a warning dialog box that tells you that the modifier depends on topology that may change. You can eliminate this problem by collapsing the Modifier Stack.
You can disable the warning by selecting the "Do not show this message again" option on the dialog box or by opening the Preference Settings dialog box and turning off the Display Topology-Dependence Warning option in the General panel of the Preference Settings dialog box. Disabling the warning does not make the potential problem go away; it only prevents the warning dialog box from appearing.
