CogEllipticalAnnulusSection.SetFromUnitCircleParams Method

CogEllipticalAnnulusSection SetFromUnitCircleParams Method

Cognex VisionPro 9.8 SR1

Set the geometry of this annulus section from the given unit circular arc, the linear transform that maps it to an elliptical arc, and RadialScale. The unit circle arc is centered at (0,0), has a radius of one, and has the given start angle (in radians) and span (in radians).

Namespace: Cognex.VisionPro
Assembly: Cognex.VisionPro.Core (in Cognex.VisionPro.Core.dll) Version: 75.0.0.0

Syntax

C++

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public void SetFromUnitCircleParams(
	double unitCircleAngleStart,
	double unitCircleAngleSpan,
	double radialScale,
	CogTransform2DLinear ellipseFromUnitCircle
)

public void SetFromUnitCircleParams(
	double unitCircleAngleStart,
	double unitCircleAngleSpan,
	double radialScale,
	CogTransform2DLinear ellipseFromUnitCircle
)

Public Sub SetFromUnitCircleParams ( 
	unitCircleAngleStart As Double,
	unitCircleAngleSpan As Double,
	radialScale As Double,
	ellipseFromUnitCircle As CogTransform2DLinear
)

Public Sub SetFromUnitCircleParams ( 
	unitCircleAngleStart As Double,
	unitCircleAngleSpan As Double,
	radialScale As Double,
	ellipseFromUnitCircle As CogTransform2DLinear
)

public:
void SetFromUnitCircleParams(
	double unitCircleAngleStart, 
	double unitCircleAngleSpan, 
	double radialScale, 
	CogTransform2DLinear^ ellipseFromUnitCircle
)

public:
void SetFromUnitCircleParams(
	double unitCircleAngleStart, 
	double unitCircleAngleSpan, 
	double radialScale, 
	CogTransform2DLinear^ ellipseFromUnitCircle
)

Parameters

unitCircleAngleStart: Type: System Double
The start angle of the unit circle arc in radians.

unitCircleAngleSpan: Type: System Double
The span of unit circle arc in radians.

radialScale: Type: System Double
The RadialScale of the unit circle's circular annulus section.

ellipseFromUnitCircle: Type: Cognex.VisionPro CogTransform2DLinear
The transform that maps the unit circle circular annulus section to this elliptical annulus section.

Events

Event Type	Reason
CogEllipticalAnnulusSection Changed	Fires when the shape changes. The following state flags may be affected:

Event Type

Reason

CogEllipticalAnnulusSection Changed

Fires when the shape changes.

The following state flags may be affected:

Exceptions

Exception	Condition
ArgumentException	unitCircleAngleSpan = 0.0.
ArgumentException	radialScale <= 0.0 or radialScale = 1.0.
ArgumentException	ellipseFromUnitCircle is NULL.

Remarks

Sets the geometry of this elliptical annulus section from a unit circular arc, a linear transform that maps it to an elliptical arc, and a radial scale. The unit circle arc is centered at (0,0), has a radius of one, and has the provided start angle and span measured in radians.

Typically, the unitCircleAngleStart value is not the same as AngleStart, and the unitCircleAngleSpan is not the same as AngleSpan. The returned unitCircleAngleStart is normalized to be between +π and −π, but unitCircleAngleSpan is not.

The child space of this shape is unit circle space. In the unit circle child space, you can pick (x,y) positions along the arc using standard parametric equations for x and y:

x = cos(t) and y = sin(t)

where the angle t varies from unitCircleAngleStart and (unitCircleAngleStart + unitCircleAngleSpan).

You can map positions and angles in child space to the parent space using the ellipseFromUnitCircle transform. You can map from parent space to child space using the inverse transform.

Remember that AngleStart is measured from the x-axis of the ellipse. You must add Rotation to AngleStart to get the correct angle in parent space.