Curves

igds_type: igds_curve

Curves are IGDS type 11 elements which are used in Design files to represent smooth Bézier curves.

Curve features have four extra points which are used to determine the slope at the starting and ending points of the curve. These points are not part of the real coordinates of the feature, and are stored in the attribute list igds_curve_slope{}.

The first two entries in the list define the slope points for the start of the feature, and the last two define the slope points for the end of the feature. The IGDS reader and writer interpret the curves coordinates as the points which define the curve. If the Preserve Curves checkbox is enabled, then the reader does not interpolate points along the curve. If curves are not preserved, they will have interpolated points added to them and igds_curve elements will be returned as igds_line elements.

A curve feature has these attributes:

Attribute Name	Contents
igds_curve_slope{0}.x igds_curve_slope{0}.y igds_curve_slope{0}.z igds_curve_slope{1}.x igds_curve_slope{1}.y igds_curve_slope{1}.z	The ground coordinates of the slope points for the beginning of the feature. If the design file was two-dimensional (2D), then the .z attributes will not be present.
igds_curve_slope{2}.x igds_curve_slope{2}.y igds_curve_slope{2}.z igds_curve_slope{3}.x igds_curve_slope{3}.y igds_curve_slope{3}.z	The ground coordinates of the slope points for the end of the feature. If the design file was 2D, then the .z attributes will not be present.