quadPoints: Calculate Points on a Bezier Curve
In pmur002/gridbezier: Bezier Curves in 'grid'

Description Usage Arguments Details Value Author(s) Examples

Calculate points on a Bezier curve and/or tangents and/or normals to the curve at those points.

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quadPoints(x, range = NULL)
quadTangent(x, range = NULL)
quadNormal(x, range = NULL)

`x`	A `"quadGrob"` object.
`range`	The range of `t` values within which to calculate points (or tangents or normals). A numeric vector of length 2.

The tangents and normals are 1 inch in length.

All functions return a list with components x and y. For quadPoints these are locations on the curve. For quadTangent and quadNormal, these are the distances to the end points of tangent or normal line segments. All values are in inches.

Paul Murrell

x <- quadGrob(c(.2, .5, .8), c(.2, .8, .2),
                stepFn=function(...) seq(0, 1, length.out=10))
grid.draw(x)
pts <- quadPoints(x)
grid.circle(pts$x, pts$y, default.units="in", r=unit(.5, "mm"),
            gp=gpar(fill="black"))
tan <- quadTangent(x)
grid.segments(pts$x, pts$y, pts$x + tan$x, pts$y + tan$y,
              default.units="in", gp=gpar(col="green"))
norm <- quadNormal(x)
grid.segments(pts$x, pts$y, pts$x + norm$x, pts$y + norm$y,
              default.units="in", gp=gpar(col="red"))