cubic-bezier

A library for constructing and evaluating cubic Bézier curve paths.

Install

(ql:quickload :cubic-bezier)

Usage

(make-curve points &key (divisions 100))

Create a cubic Bézier curve path from the given sequence of points. points is a sequence of 3-dimensional vectors as constructed with #'origin.vec3:vec. divisions is the number of sub-divisions to use when estimating the arc-length of the curve path: see the documentation for #'evaluate for more information.

(add-points curve points)

Append the specified points to curve. points should be a sequence of 3-dimensional vectors as constructed with #'origin.vec3:vec. NOTE: It is an error to add less than a segment worth of points. A cubic Bézier curve is defined by 4 points for the first segment, and three points for each successive segment (since the first point of a segment is shared with the last point of the previous segment.)

(edit-point curve index value)

Edit the point of curve at index index with value. value should be a 3-dimensional vector as constructed with #'origin.vec3:vec.

(evaluate curve parameter &key even-spacing-p)

Evaluate curve at parameter parameter. If even-spacing-p is non-NIL, arc-length re-parameterization is applied, which evenly spaces points along the curve. The number of points is defined by the divisions argument supplied when constructing the curve with #'make-curve. Arc-length re-parameterization is a remapping of parameter before evaluating the curve, in order to allow for uses such as animation along a curve with a constant velocity.

(point-count-valid-p point-count)

Check whether the integer point-count is a valid number of points for a cubic Bézier curve path. To be valid, there must be at least 4 points, any increment of 3 thereafter: (4, 7, 10, 13, ...).

(point-index-present-p curve index)

Check if curve has a point at index index.

(collect-points curve count &key even-spacing-p)

Evaluate count points along curve, returning a list of 3-dimensional vectors. If even-spacing-p is supplied, arc-length re-parameterization is applied: see the documentation for #'evaluate for more information.

(collect-segments curve count &key even-spacing-p)

Collect a list of count segments of curve. A segment is a list of two 3-dimensional vectors. If even-spacing-p is supplied, arc-length re-parameterization is applied: see the documentation for #'evaluate for more information.

License

Copyright © 2021-2022 Michael Fiano mail@mfiano.net.

Licensed under the MIT License.