Cloth Simulation II Pertemuan 08

Matakuliah : UO714 / Technology for Animation

Tahun : 2009

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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 ConsWhen 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.

Modeling Cloth Tips

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Effect of Geometry on ClothIdeally, 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.

How Cloth Work

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Cloth Mesh DensityIt 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.

How Cloth Work

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Cloth Mesh Density

Notes on the HSDS ModifierUsing 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.

How Cloth Work

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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

Object Property Dialog

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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.

Cloth Property Group

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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.

Cloth Property Group