Smooth curve drawing using a Bessel function

摘要

It is often needed to draw curves while programming. In general, it is easy to draw the line but it looks ugly. Drawing curves, especially smooth curves, complex interpolation calculations are required. To draw smooth curves, this paper introduced Microsoft's API function algorithms based on the calculation of control points. A Bessel function is different from a Bessel curve. The Bessel function is developed by Microsoft and it is packed as one of the WINDOWS functions. As part of the Microsoft WINDOWS system, it's mainly used to draw Bezier curve. Due to copyright protection, as well as other API, Microsoft provides only application interface. As for how to implement internally, algorithm and calculation formulas, belong to secret category. Microsoft will not be made public. A Bessel function, like other API functions, runs fast, not memory-resident and has less parameters etc, so it is suitable for all kinds of curves drawing. This paper proposed the algorithm to draw smooth curves using this function and programmed the algorithm by Visual Basic programming language.