Learning Blender 3D - mesh smoothing the sword model
In the previous chapters we learnt about setting up and using a simple concept sketch as the background to a scene so we could use it as a basis to make a simple low poly sword model by building an object around the general appearance of the sketch.
The next stage in the process, once the sword model is actually built, is to apply something called "Smooth Shading" in Blender, more commonly referred to as "Mesh Smoothing" and/or "Smooth Groups".
In this chapter we'll discuss the above; what it is, what it does and how to properly apply it to a mesh.
It's recommended that you have gone through the previous chapters before reading the following; done the making a simply wooden chair exercise, or have at least a basic understanding of using Blender to make models.
Making a sword, recap ^
To recap what's been done so far. Following the tutorial up to this point should have the mesh editing aspect of the sword model done so that it looks like the images below - a recognisably shaped 'sword'.
In "Wire" view ("Z") we can see the general structure of the mesh and how the position of various 'edge' and 'vertex' elements describe the shape of the object.
In "Solid" view ("Z") we see the swords outward appearance as an 'object' that has shape, form and mass.
"Wireframe" view of the sword model in it's finalised structural state showing how the various elements of a mesh - the edges, vertices and faces - are positioned to form the overall shape of an object [see *.blend "22"]
"Solid" view of the sword in "Edit" mode after final construction showing an object with form and mass [see *.blend "22a"]
What is Mesh Smoothing ^
Generally speaking "Smooth Shading" is about relationships, how different elements of a mesh, the "vertices", "edges" and "faces" interact and for the purposes of this tutorial, how that interaction becomes an interdependency that has a direct affect on surface lighting and object 'shading' (illumination). By default all surfaces are treated as individual elements when lit which causes objects to appear facetted (shown below). Smooth shading helps alleviate this problem by averaging light across shared elements, typically ones that are grouped together.
There are essentially two components to 'Smooth Shading'. 1) "Smooth Shading", or "Mesh Smoothing" as its more commonly called, is what the technique is referred to as in a 'global' sense when applied to an object - "the object has had 'mesh smoothing' applied to it". And 2) "Smooth Groups", a means by which 'Mesh Smoothing' can be controlled - "the objects has different smooth 'groups' applied to help define surfaces relationships". Although both are frequently used to describe the same thing, "smoothing", in practice they're not and as such have different implications when applied to a mesh. The proper relationship between the two is;
- Parent: Mesh Smoothing
- Child: Smooth Group 1
- Child: Smooth Group 2
Solid view of the sword showing it's final structural appearance. Also shown are the 'facets' of each individual face prior to using "Mesh Smoothing" [see *.blend "22b"]
Why is Mesh Smoothing important ^
Mesh Smoothing is an important tool for game and low poly models because it helps to define a number of interrelated factors including the 'type' of surfaces an object is supposed to be made from - whether an object is supposed to be made from something 'hard' or 'soft'; it hides the often low poly nature of curved or organic shapes by creating the illusion of greater 'mesh-density' than there actually might be; as well as ensuring objects are correctly and uniformly lit.
Assigning Smooth Shading to a mesh ^
To use "Mesh Smoothing" it first needs to be applied to the mesh. This can be done in both "Edit" and "Object" mode. There is a difference between the two however, assigning mesh smoothing in 'Edit' mode typically means that only the selected elements are affected, whereas in 'Object' mode smoothing is typically applied to the entire object uniformly. In practice this means that if we are already in 'Edit' mode press "A" to "Select All" and then click the "Shading:" toolshelf button to the left of the screen marked "Smooth" ("Mesh » Faces » Shade Smooth"). On the other hand, if you are in 'Object' mode ("Tab"), RMB click to the select the object and similarly click the "Smooth" button in the toolshelf's "Shading:" sub-section. In both instances this assigns mesh smoothing to the entire object (shown below).
Applying "Mesh Smoothing", or "Smooth Shading" as it's called in Blender, to the mesh which averages the way faces are lit across the entire model [see *.blend "23"]
Mesh smoothing - smooth groups ^
When smoothing is assigned to an object what's essentially happening is the application of a single global smoothing 'group' over an entire mesh. This results in all surfaces being treated the same way, particularly where lighting and shading are concerned. Unfortunately it also tends to make everything look a little 'mushy' and ill-formed.
The solution is to break the default uniform group into several smaller groups, creating areas that are defined by hard edges which we can use to our advantage; swords have a set of inherent properties for example because they're typically made from hard materials that have equally 'hard' edges; smooth groups can be assigned to a mesh in such a way as to give a similar impression of 'hard' surfaces. In a nutshell this is what using smooth groups is about; defining the physical characteristics of materials through the use of hard/soft edges and/or groups of face, vertex and edge elements. There are several ways to achieve what we need here, all of which perform the fundamental action, for sake of this tutorial however we'll focus on one, using the "Edge Split" modifier. Initially we'll focus on the blade.
RMB click the mesh to select it and press "Tab" to switch to "Edit" mode (if not already in it). Press "Ctrl+Tab" and select "Edge" to change selection mode (or click the 'Edge' icon in the view's menu area).
Design note: remaining in "Vertex" select mode makes selecting individual edges slightly tricky because an 'edge' in that mode is defined by a vertex at either end. This means when selecting two or more 'edges' one is potentially activating for selection the face those same vertices are constituent components of.
Using "Alt+Tab" to switch selection mode to "Edges" to make setting up "Smooth Groups" easier - selecting vertices typically highlights entire faces rather than necessary elements actually wanted
Next, using a combination of "Alt+RMB" to loop-select and "Shift+RMB" to de/select individual elements, select the edge loops that border each side of the blade area, down the back and around the connecting loop between blade and guard, in affect isolating the blades from the handle and 'framing' each sub-element. This predefines each area as a "mesh-group" which is then used to determine several separate 'groups' for smoothing.
"Alt+RMB" and "Shift+RMB" selecting the edges around the blade to define the two side faces and back of the blade. Note also the edges selected where the blade joins the handle guard so it can be properly 'isolated' and smoothed [see *.blend "23b"]
With the edges selected, make sure the mouse is over the 3D view and press "Ctrl+E" to open the "Edges" pop-up menu, select "Mark Sharp" to apply the tool ("Mesh » Edges » Mark Sharp"). The edges will turn dark red in colour to indicate they've been appropriately set.
Using "Ctrl+E" to open the "Edges" menu to mark selected elements "Mark Sharp" which will mark the edges and colour them 'red' for identification purposes
Marking edge elements creates a set of 'groups', a collection of face that form the basis upon which smooth grouping is composed - each delineated by a 'marked' edge [see *.blend "23c"]
Edge Split modifier ^
Once edges have been suitably marked a "Modifier" needs to be applied, for mesh smoothing and smooth groups we need to use "Edge Split". In the "Properties" section to the right side of the screen click the button with the "Spanner" or "Wrench" icon on it to open the "Modifiers" properties panel. Make sure the sword mesh is selected ("select all" if in Edit mode) and click the "Add Modifier" drop-down menu to access a list of available tools, selecting "Edge Split"; this activates an additional set of options and makes the mesh appear 'facetted' in the 3D window. This isn't quite what we want at the moment because the previously marked edges are not yet properly delineating groups or where the mesh is supposed to be 'split'. In the tool options that appeared leave "Sharp Edges" as is and deselect (uncheck) "Edge Angle", this forces Blender to use only the aforementioned flagged edges to define where mesh splits occur.
Assigning the "Edge Split" modifier to 'the mesh used to force "Smooth Groups" [see *.blend "24"]
Default settings for the "Edges Split" modifier uses both marked and angle based assignments. Note "Edge Angle" tend to facet the mesh as a result of the angle of incidence setting "Split An:" - make sure that "Edge Angle" is deselected [see *.blend "25"]
Adding smooth 'groups' ^
With the "Split Edge" modifier applied we can now go on to create additional 'groups' for the pommel, handle and guard areas of the sword by using the same edge marking process as before. Select the loops at the 'blade <-> guard', 'guard <-> handle' and 'handle <-> pommel' joints (shown below) using a combination of "Alt+RMB" and/or "Shift+RMB" and then press "Ctrl+E" again, selecting "Mark Sharp" as before; because the "Edge Split" modifier is now active, the mesh will instantly update with these new splits, resulting in the creation of separate 'guard', 'handle' and 'pommel' smooth groups not too dissimilar from those shown in the images below.
Design note: To remove smooth groups, edges marked as 'sharp' have to be cleared. Select the edge to be removed from a grouping and press "Ctrl+E" to open the Edges menu again, this time select "Clear Sharp" ("Mesh » Edges » Clear Sharp"), the 'sharp' edge should disappear and the any neighbouring groups 'joined' together into a larger grouping.
Marking out additional smooth groups by 'flagging' specific edge loops, to ensure only edges thusly marked determine smoothing, un-checking "Edge Angle"
Perspective view of the additional edge loops marked to create additional smooth groups within the overall mesh smoothing
Final 'solid' view of the sword mesh, the mesh smoothing and the smooth groupings contained within it [see *.blend "26"]
Next, well discuss materials and setting those up to use images as textures.