Deferred Application or

In the definition of a higher order stroke, we are faced with the question of whether to treat the appearance of the sub-strokes as geometric attributes which deform with the main stroke or just cosmetic attributes akin to pseudo-pen size in the final coordinate space[12]. The answer to this determines whether we apply the sub-strokes before defining the main stroke (sub-strokes being merely geometric objects of the main stroke) or whether we apply them after applying the main stroke (i.e. sub-strokes are applied onto newly deformed application paths). The former option would not involve application of the sub-strokes to potentially curlier paths and are referred to as the flattened definition. Flattened definition is easy to handle and is more efficient. It would, however, fail to take advantage of an important feature provided by the skeletal stroke framework: the anchoring mechanism. Furthermore, it cannot be used with self recurring strokes, since it is not possible to determine the 'self' stroke's appearance before it has been applied. In this case, either the deferred application (the second option) or the Measured Rendering Algorithm[4,5,6] must be adopted.

In our system, both options are available with deferred application as the default. With the case of deferred application, we still have to decide what to do with the resulting width of the sub-strokes. Under this mode, the resulting widths at different parts of a sub-stroke would differ in relation to the position and orientation of the main stroke. Even for strokes undergoing affine transformations, the determination of the 'correct' width is a problem. For sub-strokes subjected to highly irregular skeletal transformation, this becomes very difficult. Possible approaches adopted by us are to either reduce the width of sub-strokes to an invariant or to scale it in proportion to the width the resulting

Deterred application Flattened definition

Figure 9: The stroke definition on the left is made up of a square and 8 applications of a stroke resembling a brush. Different results with deferred application (middle) and flattened definition (right) are shown.

Deterred application Flattened definition

Figure 9: The stroke definition on the left is made up of a square and 8 applications of a stroke resembling a brush. Different results with deferred application (middle) and flattened definition (right) are shown.

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