Modifiers

Like it sounds, modifiers modify the properties of the object they are used upon. But where are these modifiers, and what exactly do they do? Well first, start by increasing the size of your properties pane (it’s the one with ), and click on the wrench symbol (signifies modifiers).

Like it sounds, modifiers modify the properties of the object they are used upon. But where are these modifiers, and what exactly do they do? Well first, start by increasing the size of your properties pane (it’s the one with ), and click on the wrench symbol (signifies modifiers).

Then, click ‘Add Modifier’, and select any option to add a modifier. Now notice, apart from the visual distinction (or perhaps not depending on modifier), there is a cross to the right of the modifier tab. 

Note, that Blender’s modifier workflow is non-destructive, i.e. regardless of how many modifiers are added, or however much change it has brought, if it hasn’t been applied to the object data, the changes are reversible. This, and the stacking of modifiers when needed make them an extremely powerful tool. 

Taking the bevel modifier as an example, notice the top bar. It starts with a downward-facing triangle, which is used to minimize its appearance so only the top bar is left, and its options are hidden. Next, are the icon and name of the modifier, after which are 5 icons. These are:

  • Visibility in render view (camera): Since it is beyond the scope of this course, it will be ignored
  • Visibility in viewport (eye): Toggling this on and off by clicking on it, toggles the visibility of the effect of the modifier on the object.
  • Visibility in edit mode (4 vertices selected): Toggling this icon, toggles the visibility of the effect in edit mode. 
  • Upwards/downwards facing arrow: Selecting the former option sends the modifier above in the modifier stack, whereas the latter sends it up.

Below those, you will find 2 buttons, “Apply” and “Copy”. While copy merely duplicates the modifier into another with similar properties, the function of the “Apply” button is slightly more complicated. The “Apply” button applies the properties given by the modifiers, i.e. changes the object data itself, making it a destructive, and almost-irreversible action, which you should caution against before using.

Subdivision Surface

Subdivision refers to increasing the number of pieces a surface is made of, and often smoothing of those extra generated piece. It is probably more intuitive to try it out, and fiddle with the settings. 

To use this modifier, add the modifier through the method specified above. You will be greeted with this:

Let’s break this down, so upon immediately adding the modifier in the modifier stack (the space for modifiers in the properties pane), you may have noticed the shape of your object has changed in a rather odd manner. 

This is what will happen to a cube, by default. There is a radio toggle above the subdivision options, allowing you to switch between ‘Catmull-Clark’ and ‘Simple’. The former smoothes out the vertices after dividing them, whereas the former only divides them. You can notice the effect of the latter better by entering the wireframe mode, by pressing Z. Now, if the effect of ‘Simple’ subdivision isn’t visible, why would it ever be used? Well, it is used when the pre-existing mesh geometry doesn’t have the sufficient number of vertices.

Below the heading ‘Subdivisions’ there are 2 numeric fields, ‘View’ and ‘Render’, of this only ‘View’ is of concern to us and it specifies the ‘level’ of subdivision visible, which is how segmented do you want the divided surface to be. Click on the right-arrow, to notice the effects it has. You can ignore the options under ‘Options’.

This is a cube with a subdivision level of 6, with ‘Catmull-Clark’. The subdivision surface can also be added more conveniently, by placing the cursor in the viewport and then pressing CTRL+<LEVEL OF SUBDIVISION>.

Array Modifier

Although it may not seem so, the array modifier is much simpler to understand. Once you add it initially, if you apply on the default cube, you will get something like this:

Well, this isn’t very descriptive of its actual function.

The parts in blue are the main relevant parts, which we will focus on. First, try increasing the count, and you’ll notice the length of the cube increasing. Under the ‘Relative Offset’ checkbox, in the first numeric field, increase and decrease the field, helping you realize how the ‘Array’ modifier simply makes copies of the base object, and places them a ‘relative offset’ away.

The numeric fields are listed as X, Y and then Z vertically. The relative offset refers to the dimensions of the object, i.e, if you set it to 1 in the X field, it will appear exactly the X dimension of the object away. Likewise, the ‘Constant Offset’ setting, if you enable, works on global units, instead of depending on the objects dimensions.

Boolean Modifier

We will be going over the basics of this modifier, which is often quite useful. This modifier requires 2 objects, so 

  1. Apart from the default cube, add another cube, or other mesh. 
  2. Change its position to overlap with the initial cube mesh

Then, go ahead and add a ‘Boolean’ modifier to the initial mesh. Click on the eyedropper, and select the other object. You may notice a change like this, from left to right, so what’s happening?

Well, basically, due to ‘Intersect’ being chosen as the operation, only which sections which intersect both objects remain in the first object. This modifier dynamically changes the intersect volume as you move it around. Its best to hide the second object to notice its effect.

The image on the far-left shows the intersect, with the 2nd object hidden. The middle image shows the object with the ‘Union’ operation, which basically combines both the meshes data. Lastly, the image on the far-right shows the initial cube with the ‘Difference’ operation, which subtracts the volume covered by the 2nd cube from the 1st.

Edit Mode Contd.

Proportional Editing

This looks difficult to edit vertex by vertex, if you wanted to make a change which affected different vertices, in slightly different ways. Sure, you could choose multiple vertices and change them simultaneously, but that would only reduce the effort slightly/negligibly. A far better method, is the proportional editing tool. 

Enable it by pressing O. The icon which changes signifies the proportional editing tool. We’ll discuss the falloff options later, first try it out.

Select a single vertex, and attempt to move it, you would notice that many other vertices are also moving along with the selected vertices, and you would notice the similar if you selected multiple vertices. The white circle surrounding your cursor when you perform any operation, is the ‘circle of influence’, and decides vertices how far can be under the influence of the initial vertex(/ices)/face(s)/edge(s). You can increase or reduce this, by middle-mouse scrolling.

Now, the falloff comes into play. The falloff specifies how the other nearby vertices in the circle of influence will be affected by the operations performed on the selected elements. For displaying this, a subdivided plane is quite useful (you can create one by creating a plane, applying subdivision, setting type to ‘Simple’, increasing the number of subdivisions and then applying). The falloff options are described in terms of the effect they have to vertices as the distance from the selected element increases, and are demonstrative visually, although some explanation doesn’t hurt:

On the left, is random offset, which, you guessed it, displaces vertices randomly. On the right, is the constant offset, which offers the same capability as if you selected the elements in the sphere of influence and operated on them directly.

The one on the left is ‘linear’ offset, hence resembles a pyramid. The one on the right is ‘sharp’.

The one on the left is ‘inverse square’, the one on the right is ‘root’.

The former is ‘sphere’, approximating a sphere, whereas the latter is ‘smooth’.

Mean Creases

Suppose you have a figure like this, where you want a subdivision surface modifier added, however still want the shape to stick to the original faces, what do you do? Well, one common method is to simply add loop cuts, however there is a much cleaner and effective method: mean creases.

You must be wondering now, what are mean creases, and how do you use them?  

Start by toggling the toolbar on the right of the viewport, by pressing T. Next, under ‘Edge Data’, drag the numerical slider of ‘Mean Crease’, and see the magic happen.

The image on the left and right show the before and after of mean crease applied, respectively. You can enter any value between 0 and 1, and the element will stick closer accordingly. The shortcut for it, which is easier to use, and usually more useful, is SHIFT+E.

Assignment

Your final assignment for this course is to model the Saturn V rocket, used for transporting the Apollo missions, and most powerful rocket ever launched, although it is currently retired. Although the material in the course is sufficient, feel free to search up more resources online. 

Tip: Search for blueprints, they help you get precise details.

Submit the appropriate model .blend file at aeross@dpsrkp.net, or ashvin.vermarocks@gmail.com, with “3D Course Submission 2019 – <NAME> <CLASS>”, where you replace <NAME> with your own name, and <CLASS> with your grade and section.

Further Reading(scroll down to Introduction to 3D Design)