How to Use the Build Modifier in Blender 3D

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How to Add the Build Modifier in Blender

To use the Build Modifier in Blender, select the object we want to have built (or un-built) and go to the modifiers tab in the Preferences Panel. Press “Add Modifier” and find the “Build” modifier under the generate column.

We may notice the object disappear. Don’t panic, it’s supposed to do that. It defaults to building the object (rather than deconstructing it). So if we are on frame #1 of our animation, the object hasn’t been built yet.

The Build Modifier works with the faces of an object. It builds or deconstructs the object face-by-face. So we may need more (or fewer) faces in our geometry to get the effect we are looking for. Too little geometry won’t give Blender much to build with.

Blender Build Modifier Settings

The Build Modifier is fairly simple. There are really only four settings for it.

Reversed

Next we have a check box option titled “reversed.” When we check this box, it causes the Build Modifier to deconstruct the object rather than build it. So it’ll start fully constructed and at the end, it will be gone.

Without the box checked, the object will begin unbuilt and end fully constructed.

Randomize

The final check box is to randomize the order in which the Build Modifier animates the construction of the faces of the object. The faces will generate (or de-generate) in a random order. Below the randomize check box is a “seed” option.

Any time we see a “seed” value, it is a way to choose a different randomization. So, if we don’t like the random selection, we can change the seed value until we do. Each value gives us a different randomization.

So that’s really all the options for the Build Modifier, but there is one thing that is commonly asked by Blender users. How do we change the order in which the object is built?

How to Change the Build Modifier Sort Order

Behind the scenes in Blender, every object’s elements are sorted and given an order. So one of the faces is “face #1.” Another is “face #2” and so on.

This hidden list doesn’t usually matter except that the Build Modifier generates an object’s faces in the order they are on this hidden list.

(Once we choose a sort option, go back into object mode and play the animation to see how it works)

View Z Axis

This sorts the faces (based on the current viewport view) from farthest to nearest. We can sort by nearest to farthest by selecting this option and then selecting the “reverse” option below.

View X Axis

This sorts the faces (based on the current viewport view) from left to right. We can select this option and then select “reverse” to sort from right to left.

Cursor Distance

This may be the most useful. Place the cursor somewhere in the scene and choose this option to build the object based on cursor distance. The faces closest to the cursor will build first. The ones farthest away will be built last. Select this and then select “reverse” to do the opposite.

Material

This option will sort the faces by material index. With this option, the materials will be built in the order they appear in the materials panel. We can re-order the materials in the material panels and sort again for a different order.

Selected

This will take whichever faces we have selected and move them to the top of the sort order. This will result in the selected faces being built before the unselected faces.

Randomize

This option randomizes the order of whichever faces we have selected. The reason we would do this rather than use the “randomize” check box in the modifier panel is that we can limit it to the selected faces.

We could select one portion of our mesh, randomize it, and then randomize a different portion of the mesh. Mixing and matching can create interesting build orders.

Reverse

The reverse option reverses the order of any order we currently have for the selected faces.

If you want to visualize the Build Modifier, here’s a detailed video explanation:

Conclusion

Any time we re-sort our mesh’s elements, the previous sort order acts as a tiebreaker or secondary sort order. For example, if we sorted them from top to bottom and then sorted them by material, it’d build the first material from top to bottom and then the second material from top to bottom.

For more, see the Blender Manual’s page about the Build Modifier.

Play around with the order and create some interesting builds. Stay creative!