Getting Started

Introduction

Subdivision surfaces combine all the good features of NURBS and polygonal surfaces; they allow organic shapes to be modeled easily and define perfectly smooth shapes with a varying surface.

Realsoft 3D provides a very powerful set of tools for modeling with subdivision surfaces.

This tutorial goes through a number of basic modeling examples for beginners.

Creating a coffee cup

The SDS toolbar allows you to create basic subdivision surface objects.

SDS tool bar

1. Select the SDS/Cube tool. As usual, the control bar now shows you a number of subdivision cube specific options.

2. Now switch to the top view and define the cube through the view window by entering two points with the mouse. While doing this, you may hold down the Shift key in order to achieve a symmetric cube. A subdivision cube is created.

A subdivision surface defined by a cube-like control polygon
 
As you can see, the created cube defines an object which doesn't look like a cube at all.  In fact, the cube tool created an object, which more or less looks like a sphere!

However, it is relatively easy to turn this spherical object to a coffee cup, or whatever other shape, as we will see soon.

This is actually a very common situation when modeling with subdivision surfaces. One starts from a very simple object, such as a cube, and adds details to it using different subdivision modeling tools.

Select the created subdivision object. As usual, the tool control bar automatically shows you the appropriate subdivision modeling tools.

The control bar shows you the tools, which can be applied to the selected subdivision object

As you can see, most of the tools are disabled. The reason for this is that most of the subdivision modeling tools can only be applied in the 'Edit' mode.  

Subdivision objects provide three kinds of editing handles: faces, edges and points.

Point handles allow you to single point edit the subdivision object. There are also a number of tools, which can be applied to points. Edges allow selection and modification of edges. The face mode allows us to select the whole faces to edit.

In order to turn our cube into a cup, we will be using the face handle mode

Select 'Face' from the Control Bar's 'Edit' field.

Enter 'Face' mode under the 'Edit' button
 
Select the top face by clicking it with the left mouse button. The selected face is highlighted.
 

Top face selected

You can now see the so called face normal handle. The face normal handle is perpendicular to the selected face and allows you to move the selected face.

Let's move the face to make our 'sphere' a bit higher. To do this, simply move the mouse over the center of the face normal handle and drag it. Note: don't drag the end points of the handle. They scale and rotate the face.

Top face moved along its normal

When you selected the top face, many of the subdivision modeling tools in the control bar were enabled. This indicates that they can be applied to the selected face.

Activate the 'Subdiv F' tool (Subdivide Face) and enter one point through the view window.

Activate the subdivide face tool

When you now move the mouse up/down, you can see the effect of the subdivision tool. When an appropriate subdivision degree is achieved, click the left mouse button again to accept the operation.

Top face subdivided

7. Now activate the 'Extrude' tool and enter one point through the view window. By moving the mouse up/down you can 'extrude' the top face up/down. If you extrude it downwards, the object starts to look like a cup.

Top face extruded inwards

Following exactly the steps described above, you can also subdivide the bottom face. In other words, rotate the view so that you see the cup from below, select the bottom face, activate the subdivide tool as above, and enter two points through the view window to define the level of subdivision.

Bottom face subdivided

Now our cup is able to stand stable which is one of the basic requirements for a decent cup.

You might wonder why the surface of the cup is not smooth but made of 'polygons'. One of the strengths of subdivision surfaces is supposed to be their 'smoothness'. Well, this is just because the real time rendering is based on polygon rendering. If you ray traced the cup, you would see the actual smooth surface:
   

Ray traced cup

You can also use the 'wire frame' compass menu to control the quality of real time rendering.

To do this:
- hold down the 'w' key
- press down the right mouse button and select the near northwest menu. This makes the cup look better also in real time rendering.
 

Use near and far northwest menus to control the real time shading quality

As you can see, with just a couple of polygons, we can define a cup with a smooth surface.

Extruding the handle

Most coffee cups have a handle. Let's see if we can use the Realsoft 3D modeling tools to create one.

There are numerous ways to create handles for the cup. Which one is the best method, depends on the case. For example, we can use the 'Extrude' tool to extrude two "tentacles" out and connect the ends of the tentacles. Let's try this.

Click the 'Smooth' tool. This subdivides the entire control polygon of the cup, producing a more dense control polygon. However, the actual shape of the cup is not changed by this operation.

'Smooth' tool

Now, select two of the side faces (one on top of the other). Use the Shift modifier to multi select.

Two faces selected

Now apply the 'Subdiv F' tool. Set 'Region' = 'Separately' from the control bar and subdivide the selected faces just like we did when we subdivided the top face in the beginning of this example.

Two faces subdivided

Now activate the 'Extrude' tool. When the tool is activated, the control bar shows you the available 'extrude' tool specific options. Enter 3 into the 'Sections' field in the control bar.

Extrude tool options: extrude with three cross sections

Now enter two points through the View window to get two tentacles extruded.

Two faces extruded with 'Sections' = 3 option

Now use the Realsoft 3D Bend tool (in the 'Transformation' toolbar tab) to give the desired shape to the handle tentacles. To do this, simply select the desired faces and bend them using the bend tool. Or, just use the usual move and rotate tools.

Extruded tentacles bent with the bend tool

Now we only need to connect the ends of the tentacles to finish the cup.

To do this, multi select both end faces of the tentacles and apply the 'Tunnel' tool. This connects the selected faces.

Click the 'Tunnel' tool.
 

Tentacles connected