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Any series of 4 distinct points can be converted to a cubic Bézier curve that goes through all 4 points in order. Given the starting and ending point of some cubic Bézier curve, and the points along the curve corresponding to t = 1/3 and t = 2/3, the control points for the original Bézier curve can be recovered. [9]
In other words, a composite Bézier curve is a series of Bézier curves joined end to end where the last point of one curve coincides with the starting point of the next curve. Depending on the application, additional smoothness requirements (such as C 1 {\displaystyle C^{1}} or C 2 {\displaystyle C^{2}} continuity) may be added.
Generally, the most common use of Bézier surfaces is as nets of bicubic patches (where m = n = 3). The geometry of a single bicubic patch is thus completely defined by a set of 16 control points. These are typically linked up to form a B-spline surface in a similar way as Bézier curves are linked up to form a B-spline curve.
The process of degree elevation for Bézier curves can be considered an instance of piecewise linear interpolation. Piecewise linear interpolation can be shown to be variation diminishing. [4] Thus, if R 1, R 2, R 3 and so on denote the set of polygons obtained by the degree elevation of the initial control polygon R, then it can be shown that
Repeat the process until you arrive at the single point – this is the point of the curve corresponding to the parameter . The following picture shows this process for a cubic Bézier curve: Note that the intermediate points that were constructed are in fact the control points for two new Bézier curves, both exactly coincident with the old one.
The bezier curve is defined by the a point moving through space. This point is the midpoint of the green line. As time goes by, the endpoints of the green line go from P0 to P1 and from P1 to P2 respectively, at a rate of distance/time.
An example Bézier triangle with control points marked. A cubic Bézier triangle is a surface with the equation (,,) = (+ +) = + + + + + + + + +where α 3, β 3, γ 3, α 2 β, αβ 2, β 2 γ, βγ 2, αγ 2, α 2 γ and αβγ are the control points of the triangle and s, t, u (with 0 ≤ s, t, u ≤ 1 and s + t + u = 1) are the barycentric coordinates inside the triangle.
For Bézier curves, it has become customary to refer to the -vectors in a parametric representation of a curve or surface in -space as control points, while the scalar-valued functions , defined over the relevant parameter domain, are the corresponding weight or blending functions.