vrmlgen (version 1.4.9)

rot.comb: Combine rotation vectors

Description

rot.comb computes the combined rotation vector for two input rotation vectors.

Usage

rot.comb(rotvec1 = c(1, 0, 0, pi/2), rotvec2 = c(0, 0, 1, pi))

Arguments

rotvec1

a numeric vector of length 4, the first 3 components specify a rotation axis and the last component is the rotation angle in radians

rotvec2

a numeric vector of length 4, the first 3 components specify a rotation axis and the last component is the rotation angle in radians

Value

Returns a numeric vector of length 4, where the first 3 components represent a rotation axis and the last component is rotation angle in radians.

Details

The rot.comb helper function computes the combined rotation vector for two input rotation vectors representing the sequential rotation of a 3D-object around two coordinate axis. In each rotation vector, the first 3 components represent the rotation axis (for the input vectors, this can be c(1,0,0) for the x-axis, c(0,1,0) for y-axis or c(0,0,1) for the z-axis), and the last component represent the rotation angle in radians. The computation is achieved by multypling the quaternion-representations of the input vectors. Please note that this multiplication is not commutative, i.e. the order of the input rotation vectors is important.

Examples

# compute the combined rotation vector for
# 1) a 90-degree rotation around the y-axis, and
# 2) a 180-degree rotation around the z-axis

rot.comb(c(0,1,0,pi/2), c(0,0,1,pi))