Check direction of polygon

Description

Check direction of polygon for Right Handed orietnation

Usage

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dircheck(pol)

Arguments

pol

list of x,y

Details

Gets cross product of consecutive points in polygon and returns the sign of each. If most are positive, should try to reverse.

Value

vector of signs

Note

Co-linear values should return zero.

Author(s)

Jonathan M. Lees<jonathan.lees@unc.edu>

See Also

rev2RH, flipZEE

Examples

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L=list()
L$x=c( 0.2188,-0.6668,-1.0992,-0.5105, 0.5106)
L$y=c( 0.76822, 0.75292,-0.01741,-0.74692,-0.48165)
dircheck(L)

K = rev2RH(L)
###  after reversing, 
dircheck(K)

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