Análisis de posibles implementaciones, componentes o módulos ya existentes y que puedan

For sweeping changes on a slightly larger scale, Soft Selection is a great tool.

Unlike other tools we’ve looked at, Soft Selection has the capability to aff ect many polygon components at once and tailor the impact to each component individually. When Soft Selection is enabled, the eff ects of the move, scale, and rotate manipulator edits will be as usual on the selected elements, but will also be distributed to adjacent polygons based on a radius and falloff . This causes edits to have a smoothed or softened eff ect on the model, resulting in an organic, clay-like feel if the geometry is dense enough.

To enable Soft Selection , select Selection > Soft Selection from the top menu, or press Alt  Shift  S . To try it:

● Create a sphere ( Create > Sphere ) ( Figure 3.10a ).

● Enter vertex selection mode ( A ) and use Tweak to drag a few vertices around ( Figure 3.10b ).

You can tell how much the transformations will aff ect individual vertices by the coloring of vertices when Soft Selection is enabled—the darker the color, the less the eff ect. The radius (the number of elements selected) can be FIG. 3.10 Soft Selection manipulation edits elements around the selection based on Radius and Falloff settings.

The eff ect of Soft Selection is most visible in a dense mesh.

Soft Selection; Selection  Soft Selection; Alt  Shift  S

Smooth

A complement to all of the expansion and modifi cation tools is the Smooth command ( Modify > Smooth ). Smooth averages the positions of the selected components’ associated vertices, evening out irregularities and extremes, and the eff ect is something magical. It basically fi xes poorly spaced and uneven geometry, and makes the job of tweaking a large mesh much easier.

To try Smooth :

^● Create a 5  5 fl at grid. Select Create > Grid > opt and set the width and depth and sections to 5. You should end up with something like Figure 3.11a .

● Now go to town messing with the grid using Tweak or the move manipulator. Move vertices up and down, pull out edges, etc.

( Figure 3.11b ).

^● Now, switch to Object Selection mode and select Modify > Smooth . Instantly, you’ll see much of the unevenness disappear as the grid smoothes out ( Figure 3.11c ). Press Smooth again to further dramatize the impact ( Figure 3.11d ).

One thing you’ll notice with Smooth is that, by its nature, it tends to reduce the size of the polygons being smoothed. This might work in your model’s favor, but might also be an undesirable side eff ect. If needed volume is lost, you can add it back in using Tweak or Soft Selection .

Smooth; Modify  Smooth;

FIG. 3.11 A messy grid can easily be fi xed with the Smooth tool.

While all modelers typically work using some kind of reference material to inform how a model will take shape, when using point modeling techniques, the reference images become indispensible and a more integral part of the modeling process. Modelers will often gather various reference photos and create their own composite image of a front and side view to use in the modeling process as in Figure 3.12 .

These images are loaded into a Silo scene by fi rst navigating to an orthogonal viewport camera (references are not visible in perspective mode) and selecting Display > Set Viewport Image .

● Try this by loading the two reference images in Figure 3.12 in the front (press 2 to enable) and right (press 6 to enable) views of a Silo scene. The images are included with the downloadable in the Chapter 3 folder as grey_alien_front.jpg and grey_alien_side.jpg.

You will want to save the fi les to a local drive before starting; the images are not saved within a Silo fi le, so if they are moved, or if the Silo fi le is moved, they will no longer be visible. You might also want to use the Vertical Split Layout so you can see both the front and side views at once ( Figure 3.13 ).

FIG. 3.12 A front and side view created by an artist in preparation for a modeling project. (Artwork courtesy of Glen Southern.)

adjusted, you can use Display > Select Viewport Image , and a manipulator will be placed on the image to allow you to move and edit it.

At times, particularly when you are using a reference image, it’s important to see through a model to get a feel for how it is lining up with the reference, and Silo provides various ways to do that. From Display > Object Display Mode or Right Click > Object Display Mode you can select Ghosted Shade Mode ( Figure 3.14b ) and Wireframe Mode ( Figure 3.14c ), which provide various degrees of transparency. The default modeling mode is Flat Shade Mode ( Figure 3.14a ).

FIG. 3.13 A Vertical Split Layout in Silo with the reference images inserted.

FIG. 3.14 Various display modes include Flat Shade, Ghosted Shade, and Wire Frame.

or P . You’ll notice the cursor has changed and, when you click, a green dot will appear. This is an indication that we are in polygon creation mode.

● Continue to click out a basic polygon shape, and as soon as three vertices are in place, you will see a shaded region where the polygon would fi ll in if it were fi nalized ( Figure 3.15a ).

● Once the fourth vertex is in place, press Enter or Right Click to fi nalize that polygon.

From there you can create additional polygons by enclosing additional space and linking vertices with the already-created polygon. It’s important to select points in a circular fashion (either clockwise or counterclockwise) to allow the software to create the face appropriately.

After creating the fi rst polygon, some modelers might elect to use something other than Append Polygon to continue a face loop. As discussed earlier, you can use Extrude edges, and one option is to select an edge, press Z , and then use Tweak or the manipulator to drag out and position a subsequent faces.

The universal or multi-use manipulator is particularly good for this, as it allows you to move and rotate as you go ( Figure 3.16 ). The Surface tool is also a great option that works in a similar fashion. It’s more commonly associated with retopology, so it’s discussed in more detail in that section. The key is to fi nd a fast and simple workfl ow that works well for you.

FIG. 3.15 Using the Append Polygon tool, you can begin to draw out a face loop.

FIG. 3.16 Using Extrusion and the Universal Manipulator, it’s easy to draw out a face loop.

Append Polygon , like many of the Silo tools, has various context-sensitive uses. If you select three or more existing vertices before calling the command, a new face will be created from the selected vertices.

● To get a feel for this, and to get set up for learning the rest of the connection tools, open a new Silo project.

selection mode, and select the bottom four central vertices in a circular order ( Figure 3.17b ). faster if you are dealing with a whole string of polygons. Rather than

connecting everything that is selected into a single polygon, Bridge will try to intelligently match up selected elements and create polygons between them.

The tool can also be used to merge and connect whole objects and to turn Bridge; Modify > Bridge;

Shift  B;

FIG. 3.17 Append Polygon can help fi ll in the gaps in a mesh.

connects separate pieces of geometry by combining them. If two vertices are selected, the fi rst will be moved to the position of the second and they will be merged to create a single vertex. If more than two vertices are selected, any selected vertices that are closer together than the tolerance specifi ed in the merge options ( Modify > Merge > opt ) will be merged with one another.

This is particularly useful if you have separate pieces of mesh whose vertices are aligned and you want to join them. If faces or edges are selected, each face or edge will be collapsed into a single vertex. This can do things like quickly turn a face loop into an edge loop, removing the extra geometry.

Let’s eliminate the hole we’ve created in our mesh from the previous commands and close a seam using Merge .

● First, select the two vertical edges surrounding the hole.

● Next, select Modify > Merge or press Control  M . The sides should now be eliminated and the top and bottom of the former hole will be a single edge ( Figure 3.19b ).

● Now eliminate the triangles on the sides by selecting the two vertices on the outside of each triangle and again pressing Control  M .

You’ll notice that the fi rst point selected merged to the second point, rather than meeting in the middle so the lines are no longer straight across.

Straighten the edges (as in Figure 3.20a ) and we can move on to merging two

^● Select the faces down the middle of the mesh we’ve created ( Figure 3 20a ) and delete.

● Next, select one of the halves of the model and move it close the second half, so they are almost touching.

● Enter Vertex Selection mode and, with box selection style, quickly select all of the vertices along the inner sides of the two disconnected halves ( Figure 3.20c ).

● Now press Control  M and each matching pair of vertices should come together ( Figure 3.20d ).

If it doesn’t work the fi rst time, try playing with the merge tolerance

( Modify > Merge > opt ) by setting the tolerance to 0.5 or higher. If only some of the points merge, you can either adjust the nonmerging vertices so they are closer to each other or continue to increase the merge tolerance.

Sculpting

One of the biggest advances in 3D modeling in recent years was the

introduction of brush-based digital sculpting, or displacement painting. It has the promise of allowing 3D artists to look at their models as a lump of clay ready to be worked on, rather than a set of points that require technical fi ddling. As of version 2.0, Silo includes a basic sculpting tool kit, and off ers something other programs can’t: the ability to switch back and forth between polygon modeling and sculpting. Displacement Painting is the only tool that can work directly with a subdivided mesh. Thus, you can still have a simple polygonal base mesh, and then sculpt details into the subdivided levels using displacement brushes.

Working with the sculpting tools is a little diff erent from working with the standard polygon editing tools. It’s conceptually much simpler but, as with polygon editing, it’s easy to get lost if you don’t take a few minutes to get your bearings. We cover all the basics in the next few sections.

FIG. 3.19 The Merge tool collapses polygons and sides and can help eliminate holes and problem areas.

FIG. 3.20 Merge can quickly close open seams.

few times, and then try each of the brushes. Some, you’ll notice, have a much more dramatic impact than others. Also important to note is that most of the brushes have an alternate or opposite eff ect. To get the basic eff ect you’ll use the Left Mouse Button . To get the alternate eff ect you use the Right Mouse Button . The size of the brush can be adjusted by holding the Middle Mouse Button or Scroll Wheel and moving the mouse (or with the Radius value in the settings screen). In general, you should see the following results:

● Push (or Sharp Push ) Brushes : These brushes add volume to the mesh. As you can see in Figure 3.22a , we’ve drawn a circle around the eye with the mouse while holding down the left mouse button. Alternatively, using the right mouse button will carve into the model.

● Smooth Brush : The Smooth Brush , much like the Smooth command, helps put the object in order by evening out variation, diminishing the impact of other sculpting tools, and decreasing volume. The right-click alternative adds noise, making the mesh rougher. In Figure 3.22b , using the Smooth Brush we have eliminated much detail from the base bust.

● Move Brush : The Move Brush is much like Soft Selection combined with Tweak . It allows you to grab a chunk of polygons and move them around

FIG. 3.21 The Brush Editor shows the displacement painting brushes available in Silo.

FIG. 3.22 The various brush tools in Silo can have very diff erent eff ects on a model.

adding organic folds, twists, and sagging ( Figure 3.22e ).

● Pinch Brush : The Pinch Brush tightens up geometry. It shrinks all the polygons within the brush’s radius, pulling in those surrounding the impact, as in Figure 3.22f , and can be used to sharpen the impact of other brushes. The right-click alternative is Infl ate , which expands all the polygons within the brush radius.