DIFFERENCE BETWEEN NURBS AND POLYGONS
Polygon models are made up of a large number of flat planes with straight line edges – the more polys, the more detail. On a sphere, more polys makes for a smoother sphere.
NURBs models are actually comprised of curves and curved line edges – so despite having less ‘detail’ than an polygon model in terms of number of lines, they can actually create similar levels of curvature from fewer lines and less ‘information’.
Polygonal objects are much more flexible and therefore more useful in terms of character animation etc so NURBS is far less commonly used.
CREATING POLYGON OBJECTS
Polygon objects start as primitives – simple shapes that can be manipulated into whatever we need them to be later – boxes, cylinders etc.
Primitives can be added to our scene in two ways – either from the menu: Create > Polygon Primitives. Or from the ‘Poly Modelling’ tool tab just above the viewport.
Note the ‘Interactive Creation’ button at teh bottom of this list. When on, you can click and drag your object into existence on the vieport, at any point in space. This object can then be adjusted in the attribute Editor or channel box.
With ‘Interactive selection’ set to off, clicking any icon in the menu will create that shape, placing it at the origin point (0,0,0 world co-ords) with the predetermined settings. Settings can be changed by clicking on the littel square icons beside each object in the menu.
SELECTING POLYGONAL COMPONENTS
To adjust our primitives towards the shapes we want to model, we manipulate their components – Vertices, edges and faces. To activate one of these modes, we right click on the model, and chose it from the radial menu at the top of the selection box.
Normally you will want to select multiple faces or vertices. Some selection tips:
Shift + L-Click will add or remove a component from your current selection
Shift +Double L-Click on two separate faces or vertices etc, will select the other ones directly between them. Useful for quickly selecting rows of vertices etc.
Double L-Click on an Edge will select an entire Edge Loop.
Shift +Double L-Click on two adjacent faces or vertices etc will select the loop.
Shift + < (or >) can be used to shrink or expand our current selection – ie selecting all the adjacent components to what we have selected.
Select > Grow Selection Region can also be used.
SOFT SELECTION AND SYMMETRY
Double clicking on the selection tools (move, rotate, scale etc) will open the tool settings box. There is a tab for Soft Selection.
Rather than moving an absolute set of vertices soft selection lets you pull and push on the mesh like it’s made of rubber. The falloff radius lets you determine how far this effect reaches on the mesh.
Holding the B key and dragging the mouse will show a circular icon that you can expand/contract to quickly change the falloff radius. Note that the B key can be used to quickly activate Soft selection without navigating to it’s menu. It must still be turned off manually however.
We also have a Symmetry Settings tab in the Tool Settings box. Here, there is a dropdown box where we can choose the axis in which we want symmetry to occur (note that the line of reflection comes from the objects pivot point). This same dropdown box can also be found along the top toolbar, for quicker access.
COMBINE AND SEPARATE
An object may be comprised of several individual meshes – for example a table may be comprised of its top, and individual legs. We can combine these into a single mesh by using the Mesh > Combine option in the menu bar.
When we combine – we will notice a few changes. Firstly, the mesh will become one. However, in the Outliner, we will still have a lot of leftover empty objects, and in the Attribute Editor we will have a new tab called PolyUnite.
To clear this Junk data, go to Edit > Delete by type > History.
Mesh Separate will separate any parts of mesh that arent directly connected, into separate objects. It will create a new group with the original objects name, and place the new objects into it.
BOOLEAN TOOLS
Booleans allow you to cut one mesh out of another – for example to add holes or vents to an object.
Select an object that you want to be cut, and then select the object that you want to be the removed. Go to Mesh > Boolean > Difference to leave the empty hole behind. You can also combine objects together into a single mesh with ‘Unify’
NB: Booleans tend to leave messy geometry behind.
SCULPTING MESHES WITH BRUSH TOOLS
Mesh tools > Sculpting tools will allow you to uses more organic tools, similar to those found in ZBrush. There is also a sculpting tab in the Tool Shelf.
With sculpting, we drag our cursor like a brush over the model, and this deforms it. Just like Soft Selection, the B key will allow us to change the size of our brush.
Double Clicking on a sculpting tool will allow you to change its options, such as size, falloff, strength, and also toggle symmetry on and off.