# Synopsis

PDX_MSGT mth_SweepAnglesLoop(long option, int dim, int num_segs, int *num_seg_pnts, long num_pnts, double *pnts, double tol, int *num_angle_ranges, double **angle_ranges, PDX_BOOL *axis_touch)

# Purpose

Find the sweeping angles of a closed loop about Z axis

# Description

The sweeping angles of a set of continuous points that are obtained from a set of continuous curves with a reasonable tight approximation tolerance, precisely, the sweeping angle of every two consecutive points about Z axis should be smaller than 180 degrees, will be computed in function. The end angle is not smaller than the start angle which is within [- MTH_ANG_EPS, MTH_2_PI - MTH_ANG_EPS).

The loop represented by these points must be continuous. If the Z axis or origin is not inside of the loop, only a pair of angles will be returned; otherwise, a pair of angles will be found for each segment or curve. The users might need to merge the results as needed.

Though only 2D data will be used, for convenience, the input can be either 2D or 3D points.

For some data, the angle ranges can not be determined. Specifically, when all or some of the points are near the origin. When such cases occur, num_angle_ranges will be returned as zero.

# Input

## option

Options (not used)

## dim

The dimension of points (2 or 3)

## num_segs

The number of segments/curves in the loop

## num_seg_pnts

The numbers of points in each segment [num_segs]

## num_pnts

The number of points

## pnts

The points array [(2 or 3)*num_pnts]

## tol

The tolerance for checking if a point is at the origin

# Output

## num_angle_ranges

The number of sweeping areas for the loop = 0, Sweep angles could not be determined >= 1, Sweep angles were determined.

## angle_ranges

The sweeping angles for all areas, each pair of values represent an area and the starting angle is not larger than the ending angle [2*num_angle_ranges]

## axis_touch

Flag indicating if the loop touches the axis

# Return

          MTH_NOERR
          MTH_ORIGIN_POINT
          Low level error return
          .fi