MIL-STD-2301A
parallel to the other diameter. The centerpoint (CenterX, CenterY) specifies the center of an ellipse. The conjugate diameter endpoints (End1X, End1Y, and End2X, End2Y) include one endpoint from each conjugate diameter. Together with the centerpoint, they define the two conjugate diameters of the ellipse. StartVectorX and StartVectorY define a start vector, and EndVectorX and EndVectorY define an end vector. The tails of these vectors are placed on the centerpoint. A start ray and end ray are derived from the start and end vectors. The start and end rays are the semi-infinite lines from the centerpoint in the direction of the start and end vectors, respectively. The define arc begins at the intersection of the ellipse and the end ray in the direction defined as follows. A "conjugate radius" is defined to be half of a conjugate diameter. Letting the centerpoint be labeled M, the first conjugate diameter endpoint P1, and the second conjugate diameter endpoint P2, then the line segments
M-P1 and M-P2 define two conjugate radii, referred to in what follows as the first conjugate radius and the second conjugate radius, respectively. The conjugate radii meet at M and define two angles: the sum of the two angles is
360 degrees, one angle is less than 180 degrees and the other is greater than 180 degrees. The drawing direction of the elliptical arc is the direction from the first conjugate radius to the second conjugate radius through the smaller
of these two angles. Valid values of the three specifying points of the ellipse are those which yield three distinct points. The specified ellipse is non-degenerate if and only if the three points are non-colinear. Valid values of the vector components are those which produce vectors of non-zero length. If the start ray and end ray are coincident, it is ambiguous whether the defined arc is null (zero arc length) or the entire ellipse. The last parameter, Close Type, specifies how the arc is closed (0=pie or 1=chord). If the close type is chord, a line is drawn between the endpoints of the arc. If the close type is pie, a line is drawn from the beginning of the arc to the centerpoint of the ellipse and then to the end of the arc. The interior of the arc will be as specified by the Interior Style command, and the edge width, type and color will be specified in the Edge Width, Edge Type, and Edge Color commands, respectively.
TABLE CX. Elliptical Arc output.
MSB LSB
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
4 19 22 0x4276
CenterX CenterY End1X End1Y End2X End2Y StartVectorX StartVentorY EndVectorX EndVectorY Close Type
5.1.2.5.7 Rectangle element output. The CGM implementation for NITFS shall provide the capability to generate and output the Rectangle element using the following format. The rectangle is defined by two distinct points that are diagonally opposite corners of the rectangle where the rectangle is oriented parallel to the VDC
axes. The interior of the rectangle will be as specified in the Interior Style command, and the edge width, type and color will be specified in the Edge Width, Edge Type, and Edge Color commands, respectively.
TABLE CXI. Rectangle output.
MSB LSB
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
4 11 8 0x4168
Corner1X Corner1Y Corner2X Corner2Y
5.1.2.5.8 Circle element output. The CGM implementation for NITFS shall provide the capability to generate and output the Circle element using the following format. The first two parameters, CenterX and
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