Matakuliah
Tahun
: UO714 / Technology for Animation
: 2009
Cloth Simulation II
Pertemuan 08
Modeling Cloth Tips
Garment Maker is a useful tool for putting together patterns and adjusting seams, but you can also achieve good results by
modeling with the standard 3ds Max tools and using Cloth on top of these meshes. You can create clothing with
polygons, patches, or NURBS.
ImportantKeep in mind that modeled clothing must not have any overlapping vertices or interpenetrating faces. This type of
geometry can cause the simulation to fail. Using Garment Maker; you will not run into this problem. If you are careful in
creating your mesh, then this is an easy rule to follow.
Pros and Cons
When designing clothing, Garment Maker is usually the best way to go. It lets you define seams, seam strength, pleats, and other
clothing parameters that cannot be defined with clothing modeled via other methods. Either methods lets you define separate
portions of your clothing with different fabrics, but Garment Maker gives you greater control over this. The advantage to using
modeled clothing is that it can sometimes be a faster setup with familiar methods and it’s a great way to repurpose older
clothing models you have made in the past. Using polygon-modeled clothing can result in overly regular creases and folds.
Garment Maker uses a Delaunay mesh, which tends to avoid this problem. However, the irregular triangulation can result
in rendering artifacts for low-resolution clothes, so it is advisable to apply the HSDS modifier after Cloth on garments created
with Garment Maker and subdivide all the triangles once.
Note :MeshSmooth does not give good results with Garment Maker meshes.
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How Cloth Work
Effect of Geometry on Cloth
Ideally, the way you model your cloth should not affect how it behaves. However, in practice, the nature of the cloth geometry
impacts the simulation. First of all, the density of the mesh defines how fine the folds are that can develop. If you create a
plane with only nine vertices, when you drape it over a sphere, you are obviously not going to get much detailed folding.
In addition to this aspect, there is the nature of the edges in the mesh. Folding can occur only at edges between triangles, so the
regularity or irregularity of the mesh also dictates the resulting deformation. For example, a plane all of whose triangle
hypotenuse edges are aligned will result in a cloth with folds aligned along those edges. Garment Maker creates meshes with
an irregular layout (but with fairly equal-sized and close-to-equilateral triangles) that avoids this folding bias. However, this can
also result in rendering artifacts with low-resolution cloths, so it is advisable to apply the HSDS modifier after Cloth on
garments created with Garment Maker and subdivide all the triangles once.
NoteMeshSmooth does not give good results with Garment Maker meshes.
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How Cloth Work
Cloth Mesh Density
It is important to think about how dense your mesh has to be to achieve the result you want. Making the mesh too dense will slow
down the system, while having your mesh at too low resolution might not give you the folds or detail you want to see.
For example, if you applied a Bend modifier to a cylinder with only a few height segments, the result would be angular and
unsmooth. On the other hand, if you created the cylinder with 1,000 height segments, you'd be wasting resources. The same
is true for Cloth. You must find a balance between level of detail and performance that is appropriate for your scene.
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How Cloth Work
Cloth Mesh Density
Notes on the HSDS Modifier
Using the HSDS modifier to add detail to your model can be an effective solution that lets you simulate with a
lower resolution mesh, and still get high-quality results. However, if you choose to use the HSDS
modifier on top of your Cloth garments, you may want to apply an Edit Mesh modifier below it to weld the
vertices together along the seams. This prevents the mesh from coming apart at the seams as it is
subdivided.
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Object Property Dialog
Use the Object Properties dialog to specify which objects are included in a Cloth simulation, whether they are
cloth or collision objects, and define parameters associated with them
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Cloth Property Group
U Bend/V Bend
Resistance to bending. The higher this value is set, the less the fabric will be able to bend. A cotton
fabric might bend more easily than leather, so a value of 15.0 for both U and V Bend might be good for
cotton, while 50.0 would work well for leather.
By default, the U Bend and V Bend parameters are locked together so that changing one sets the
other to the same value. You can set different values for the two only when Anisotropic is off. It is
recommended to do this only for Garment Maker objects.
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Cloth Property Group
Thickness
Defines the virtual thickness of a fabric for the purpose of detecting cloth-to-cloth collisions. This value
is irrelevant if cloth-to-cloth collisions are disabled. Larger values keep the cloth separated by greater
distances. Be careful not to use too large or small values in this field. Very large values will interfere
with the natural behavior of the cloth. Very small values will cause the simulator to take too long to
calculate. This distance is measured in cm (centimeters) and should be smaller than the size of the
triangles that make up the cloth object. A setting of 0.0 will let Cloth automatically assign a reasonable
value for thickness.
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