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The Domains and Handles Concept |
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The Domains and Handles Concept |
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When using the domains and handles approach, the model is divided into domains. Handles are then used to control the domains shape. When the handles associated with a domain move, the shape of the domain changes, which in turn changes the positions of the nodes inside those domains. During the morphing process the mesh morphs in a logical way with nodes near the moving handles moving more and nodes near the stationary handles moving less. In the areas between the handles, the mesh is stretched or compressed to match the desired shape.
The amount each node moves with respect to each handle is relative to an internally calculated influence coefficient. The process for calculating the influence coefficients is somewhat time consuming, but once they are calculated they can be stored and applied rapidly. Thus, when handles and domains are initially set up or edited, HyperMorph spends an amount of time (proportional to the size of the new domains) calculating the handle influences. However, when handles are moved to morph the model, no calculations are necessary and the actual morphing occurs quickly. The advantage of this approach is that it makes morphing an interactive process, even for large models.
For very large domains, calculating influence coefficients can be time consuming. For domains that have more than 50,000 elements (although you can change this default limit) the large domain solver is used. The large domain solver much faster at morphing large domains, but the drawback is that it must be invoked every time you wish to morph, thus making morphing slower. However, for very large domains, the process of calculating influences can be too slow or too memory intensive--so the large domain solver makes it possible to morph such domains.
Domains and handles are divided into two basic groups, global domains and local domains. Each global domain is associated with any number of global handles. Global handles will only influence the nodes contained within their associated global domains. Global domains and handles are best for making large scale shape changes to the model.
There are five types of local domains: 1D domains, 2D domains, 3D domains, edge domains, and general domains. Each local domain is associated with any number of local handles. Local handles will only influence nodes contained within their associated local domains. Local handles are intended to be used to make small scale, parametric changes to the model. A model can contain both global and local handles and domains, which allows for both large and small scale morphs. It is not necessary to have both types of domains and handles in a model.
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