Hooks modifier - Deforming objects proportionally in Blender

Is it possible to deform objects proportionally but still remain editable? Yes, you can use the hook modifier. The idea is that you can hook a set of vertices on the first object to a second separate object and then move or rotate that second object around. That makes the position of the second object control the vertices of the first. It’s like grabbing your vertices and moving them using a modifier – a non-destructive operation.

Let’s see how that works in practice.

Our first object is our trusty Cube. Then we’ll create the second object. This can be any object – another cube, a sphere, an existing object that you have already built. For simplicity’s sake, we’ll just create a humble Empty. brings up the Add Object menu:

Add Object Empty — *Add an Empty with lines representing axes*

Change to front ortho view and move the Empty above the cube:

Switch to perspective view [middle mouse button drag]

Change to wireframe transparent mode .

Select the Cube and toggle to Edit mode :

Change to Vertex select mode

Select the top four vertices

While the four vertices are selected, select the Empty object as well with [Left Click]:

*The 4 vertices and the Empty are now selected*

Now we designate the 4 vertices as hooks on the cube with

This image has an empty alt attribute; its file name is Hook-to-Selected.jpg

Immediately a Hook modifier is added to the Cube:

Notice that the hook icon displays the words Hook-Empty which mean that the hooks (the 4 previously-selected vertices) are now connected to the Empty.

Now let’s see how this works. Go to Object mode and Solid View with transparency

Move the Empty around :

As the Empty moves, so do the 4 vertices

Well, “big deal” you might say sarcastically, “I can just go into Edit mode, select the 4 vertices and simply move them”. But think about this for a moment. If the second were not an Empty, but another object. As you moved that object into position, the 4 vertices forming the top surface would also move the same distance. That would save a tremendous amount of tricky fiddling!

But you can do more with Hooks

Try this…

Start off with the cube again in a new drawing, and add the empty as we did above.

Select the cube and change to Edit mode

Then create 10 Loop-Cuts on each three faces:

Change to Front View ,

Switch back to Transparent Wireframe view ,

Set Vertex Select mode .

Now select the 100 vertices on the top surface. Then select the Empty object as well with [Left Click]: :

*The top 100 vertices selected as well as the Empty*

Now we designate all 100 vertices as hooks on the cube with :

Switch back to Object mode and move the empty up:

Now comes the magic:

Select the cube and increase the Falloff Radius in the modifier panel:

*The top surface of the cube begins to bend*

This deformation can now be accurately controlled by:

Selecting the Empty and moving it
Adjusting the Radius value in the Modifier panel. This can be quite critical and appears not to work if the radius is too large or too small.
Changing the Type of deformation in the Modifier panel

For accurate control, work in an Ortho view. To see the effect, look in Perspective view:

We can pretty this up further by setting Auto Smooth to a suitable angle. To smooth the faces making up the curved shape but not the vertical cube edges we would set the Auto Smooth angle to a value greater than 60 and less than 90. Then Right-Click in the viewport and choose Shade Smooth: