a class of quartic polynomial basis functions with two adjustable shape parameters is presented
which can be regarded as an extension to classical cubic Bernstein basis functions. A polynomial curve called cubic quasi-Bézier(cubic Q-Bézier)curve with shape parameters is defined to outperform general cubic Bézier curves with the inherent flexibility. The shape of the cubic Q-Bézier curve can be adjusted by altering the shape parameters when the control polygon remains unchanged. The shape modification of the cubic Q-Bézier curve by geometric constrains is investigated. A new method is presented by changing the shape parameters to satisfy the given constrains
and the corresponding simple computational formulae of the shape parameters with unambiguous geometric significance are proposed. Some practical examples verify the applicability.
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references
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