qtpaint (version 1.1.0)

qvmap: Mapping coordinates

Description

Transforms X and Y coordinates with a Qt-style transformation matrix. The advantage over direct use of Qt is vectorization.

Usage

qvmap(m, x, y)

Arguments

m

A matrix encoding the transformation, or something coercible to a matrix, like a C++ QTransform instance

x

X coordinates; if y is missing, should be something coercible to a numeric vector or matrix. If the vector coercion succeeds, the vector is coerced to a matrix with matrix(x, ncol = 2, byrow = TRUE). The first column is taken as X, the second as Y.

y

Y coordinates, optional

Value

• The mapped coordinates, as a two column (X, Y) matrix, unless y is missing, in which case an attempt is made to coerce the result to the class of x, if any.