12.1 Introduction to Modifiers 12.2 Modifier Stacks
12.3 Modifiers for Generating 12.4 Modifiers for Deforming 12.5 Modifiers for Simulating
12.1 Introduction to Modifiers
A modifier in Blender is the application of a process or algorithm upon an object. In other words, once you have created an object in the scene you can apply a neat set of data that will change the shape or way the objects behave. The modifiers are designed to take some of the hard work out of shaping an object. Be warned, though, that applying some of Blender’s modifiers is not straightforward and has to be performed in conjunction with other pro-cesses. Without some instruction on how to apply the modifiers, a lot of trial and error can be involved. To save you all that trouble, the following chapter on modifiers is offered as a guide. You will still have to experiment and record your findings to become proficient in the application of modifiers.
Modifiers are found in the properties window – “Object Modifiers” button (Figure 12.1).
The “Object Modifiers” button is only displayed when an object to which a modifier can be applied is in the 3D window. Some objects cannot have modifiers applied. Note that if there are objects in the 3D window to which modifiers may be applied (not necessarily selected), clicking the “Add Modifier” button and selecting a modifier will apply a modifier to the last object that was selected. This occurs even though that object is not selected at the time.
Figure 12.1 Properties window
“Object Modifiers” button
Start with the default Blender scene with the default cube object. Select the cube, go to the properties window – “Object Modifiers” button, and click on “Add Modifier” to display the modifier drop down selection menu (Figure 12.2). Adjust the values to produce the desired effect then apply the modifier.
Applying the modifier permanently sets the action.
12.2 Modifier Stacks
Before explaining the individual modifiers, I should note that in some cases it is appropriate to apply more than one modifier to an object. When this is done the modifiers are placed in a stack in order of priority. The priority can be changed by moving a modifier up or down in the stack. Also note that although modifiers are generally applied in object mode, some may be used in edit mode. Figure 12.3 shows an array modifier and a bevel modifier applied.
The following pages will give a basic insight into how some of the modifiers are em-ployed. The full listing of modifiers available are shown in the modifier selection drop down menu in Figure 12.4. The circled modifiers will also be covered in later chapters related to armatures (Chapter 15), particle systems (Chapter 13), and fluid simulation (Chapter 17).
Figure 12.2
Displayed modifiers panel Drop down
selection menu
Note: New modifiers are continually being added to the program and the drop down menu changes accordingly.
193 12.3. Modifi ers for Generating
12.3 Modifiers for Generating 12.3.1 Array Modifiers
Th e array modifi er creates an array of copies of the base object, with each copy off set in a number of possible ways. Figure 12.5 shows a UV sphere object with an array modifi er applied to it with “Count: 3” (the base object plus two copies equals an array of 3) and x and y off sets (“X: 1.500” and “Y: 1.000”). Th ere are three types of off set functions available:
relative, constant, and object. Note that Figure 12.5 is using the relative off set function.
With “Count: 2” and an off set along the x-axis of “X: 1,” the diff erence between relative and constant is shown in Figure 12.6. Th e object off set function is shown in Figure 12.7 and is combined with a second array modifi er.
Click to enable the modifier settings to be applied in edit mode.
Click to move the modifier up in the stack.
Click to move the modifier down in the stack.
Figure 12.3
Figure 12.4
Array Modifier Learning Unit 6
12.3.2 Object Offset Using Array Modifiers
In Figure 12.7, the vertices of the sphere object have been moved +3 Blender units along the x-axis (tab to edit mode and drag the vertices to the right). Th is leaves the center of the sphere at the center of the scene coinciding with the 3D cursor. Relocating the sphere’s vertices is merely done for clarity to move the fi nal result away from the cube. An array modifi er is applied to the sphere; the “Count” value is 2 and there is a “Constant Off set: X”
value of 6.000 (Figure 12.8). Th is creates an array with two spheres, with the second sphere displaced +6 Blender units from the fi rst.
A second array modifi er is added, but this time the modifi er is applied to the array that was created by the fi rst modifi er. Th is second array modifi er also has a “Count” value of 2, which produces an array consisting of the fi rst array plus an instance of the fi rst array. Th e second array modifi er uses an “Object Off set: Cube,” which tells the modifi er to use the lo-Figure 12.5
Figure 12.6
“Object Modifiers” button Properties window
Y = 1.000
Relative Constant X = 1.500
Multiple Modifiers
Learning Unit 6
195 12.3. Modifi ers for Generating
cation coordinates of the cube in the scene as the displacement values for the second array. Th e cube is located at x = –1.5 and y = –1.5. Accordingly, the second array of spheres is displaced from the fi rst array by these values.
12.3.3 Bevel Modifiers
Th e bevel modifi er simply adds a bevel to the corners of an object; the size of the bevel is controlled by the “Width” button (Figure 12.9).
Figure 12.7
Figure 12.9
Default cube with a bevel modifier applied
Extruded cube with a bevel modifier applied
Bevel Modifier Learning Unit 6
Figure 12.8
Center
First array
Second array
+3 +6
12.3.4 Boolean Modifiers
Boolean modifi ers are used to create shapes by using a dif-ference, intersection, or union operation between objects. To demonstrate this, we will use the default cube and a cylinder object. Be warned that, unless you have a super fast computer, some calculations can take several seconds.
Start with the cube and cylinder and position them as shown in Figure 12.10 (this will be the same setup for all three operation types). Begin with the Boolean type “Intersect.” To make sure the procedure works, set the vertices count for the cylinder to 16 (add the cylinder, then change the number of vertices in the tool shelf).
Intersect. Intersecting objects creates an object that is the shape of the overlap of two ob-jects. Th e cube will be the object that is modifi ed, so you must fi rst select the cube. Click the properties window – “Object Modifi ers” button – “Add Modifi er” and select type “Boolean.”
Th e operation type by default is “Intersect.” In the “Object” panel click on the little cube icon and select “Cylinder” in the drop down menu (Figure 12.11). Note that this panel always shows a little cube icon despite the shape of the actual object being selected.
In the “Display” tab click on “Apply” and the modifi er panel disappears. In the 3D win-dow move the selected object to reveal the new object, which is now the shape of the overlap (Figure 12.12). Th e cylinder object remains in the scene.
Figure 12.10
Figure 12.11
Figure 12.12
Start position for the cube and cylinder
Click the cube icon and add the cylinder.
Boolean
Separate the objects to see the intersection.
197 12.3. Modifiers for Generating
Union. Uniting objects creates a shape that is a union of the two objects. Add a Boolean modifier to the cube and select operation type “Union.” In the “Object” panel click the little cube icon again and select “Cylinder.” Click “Apply” and move the selected object in the 3D window; the two objects are now fused together (Figure 12.13).
Difference. Differentiating objects creates a shape that is the difference of the two objects. In other words, it subtracts the overlap of the objects from the object being modified. Follow the same procedure as the foregoing examples, but this time select the oper-ation type “Difference” and see the result (Figure 12.14).
12.3.5 Build Modifiers
The build modifier creates the effect of something building linearly over a period of time. For example, text can be animated to build across the screen. Any object can have a build modifier, but to see a nice effect, a high vertex count is required.
Add some text to the scene, select the text in the 3D window, and add a build modifier (Figure 12.15). As soon as you add the modifier, the text disappears from the screen (Figure 12.16). Press Alt + the A key to see the animation of the text building (Figure 12.17).
Figure 12.13
Figure 12.14
Figure 12.15
Figure 12.16
Figure 12.17 Text in the 3D window selected in object mode
Part of the text is showing.
Text with the build modifier added
Text building while playing the animation
Build direction
12.3.6 Decimate Modifiers
Th e decimate modifi er allows a reduction in vertex count without too much alteration to the object’s shape. Select the default cylinder in object mode and click “Add Modifi er” –
“Decimate” (Figure 12.18). Change the ratio from 1 to 0.600—notice that there isn’t much change to the appearance of the cylinder in object mode. Tab to edit mode to see the reduc-tion in the number of vertices.
12.3.7 Edge Split Modifiers
Th e edge split modifi er allows you to split an object apart by selecting vertices, edges, or faces. As an example start with the default scene with the default cube object. In object
Decimate Modifier
Learning Unit 8
Figure 12.18
Default cylinder before the modifier is applied
Default cylinder in edit mode showing the vertices before the
modifier is applied
Default cylinder after the modifier is applied with a ratio of 0.600; not too
much has changed
Tabbing back to edit mode shows the reduction in the
number of vertices.