MgraArcAngle

This function draws an arc or sector destructively (raster-based) in the specified image. Alternatively, this function can add a vector-based version of an arc or sector to the specified graphics list, allowing you to, for example, non-destructively annotate a display without pixelation effects upon scaling.

The arc or sector graphic is based on an ellipse centered at XCenter and YCenter, with radii XRad and YRad. The arc is the curve of the ellipse between the start angle (StartAngle) and the end angle (EndAngle), with an orientation along the X-axis (XAxisAngle). The arc or sector inherits all the relevant settings of the specified graphics context, such as the foreground color (MgraControl() with M_COLOR). If part of the arc or sector falls outside of the specified area (image or display), that part is clipped off. The following image shows how the parameters are used to define the arc:

The center position, radii, and angle values are interpreted with respect to the input coordinate system, specified using MgraControl() or MgraControlList() with M_INPUT_UNITS. An angle interpreted with respect to the pixel coordinate system is always measured counter-clockwise. For information on the angle's direction of rotation when interpreting the angle with respect to the relative coordinate system, see the Angle convention in MIL subsection of the Working with real-world units section of Chapter 25: Calibrating your camera setup. Note that if you set your input coordinate system to M_WORLD and you pass MgraArcAngle() an uncalibrated image or the drawing target of the graphics list is uncalibrated, the function will generate an error.

By default, only the arc is drawn in the image (M_CONTOUR). With the ControlFlag parameter, you can change this behavior to draw a sector of the ellipse (M_SECTOR) instead, with lines extending from the center of the ellipse to the start and end points of the arc. However, you can choose to draw it filled with the specified foreground color by specifying the M_FILLED combination constant.

To modify or inquire graphics context settings, use MgraControl() or MgraInquire(). To modify or inquire graphics list settings, use MgraControlList() or MgraInquireList().

To create a filled arc (sector) that is not rotated, you can also use MgraArcFill(). To create an arc that is not rotated or filled, you can also use MgraArc().

Unlike most other functions that modify a MIL object, you can call this function concurrently from multiple threads on the same MIL graphics list (DstImageBufOrListGraId) without using an M_MUTEX object, as long as all the other parameters of the concurrent calls do not also share data.