Circular Curve

Detailed Description

group a3d_crvcircle

Entity type is kA3DTypeCrvCircle.

Version

2.0

The canonical form is defined with an A3DMiscCartesianTransformationData, its origin being the center of the circle and its vector X being the axis corresponding to zero parameter. The implicit parameterization is an angle expressed as radians in the range [0, 2PI].

A3DParameterizationData lets you specify reparameterization and trim.

Here are parameterization examples:

  • To specify the interval in radians, set m_dCoeffA to 1.0 and m_dCoeffB to 0.0. These parameter values specify an identity conversion.

  • To specify the interval in degrees, set m_dCoeffA to PI/180 and m_dCoeffB to 0.0. m_dCoeffA is the ratio of radians to degrees.

In the above example, the circular arc is in the XY plane (and therefore has an identity transformation), has radius R, and is restricted to the [ t0 , t1 ] interval.../_images/A3DPRCGeometryCrvCircle.jpg

Example of a circular arc

If m_dCoeffA is 1.0 and m_dCoeffB is 0.0 and if the interval is defined as t0=0 and t1=PI/2, then t0 corresponds to the Cartesian coordinates (R,0,0) and t1 to (0,R,0). These values for the m_dCoeffA and m_dCoeffB co-efficients indicate parameterization is in radians and starts at the X axis.

Note

Radius must be greater than 0.

Warning

Radius as a parameter can be modified by A3DMiscCartesianTransformationData when the transformation defines uniform scaling.

Function Documentation

A3DStatus A3DCrvCircleGet(const A3DCrvCircle *pCrv, A3DCrvCircleData *pData)

Populates the A3DCrvCircleData structure.

Return values

  • A3D_INITIALIZE_NOT_CALLED –

  • A3D_INVALID_DATA_STRUCT_SIZE –

  • A3D_INVALID_DATA_STRUCT_NULL –

  • A3D_INVALID_ENTITY_NULL –

  • A3D_INVALID_ENTITY_TYPE –

  • A3D_CRV_CANNOT_ACCESS_CANONICAL –

  • A3D_SUCCESS –

Returns

A3D_SUCCESS in case of success or an error code

A3DStatus A3DCrvCircleCreate(const A3DCrvCircleData *pData, A3DCrvCircle **ppCrv)

Creates an A3DCrvCircle from A3DCrvCircleData structure.

Version

2.0

Return values

  • A3D_INVALID_DATA_STRUCT_SIZE –

  • A3D_INVALID_DATA_STRUCT_NULL –

  • A3D_INTERVAL_INCONSISTENT_DATA –

  • A3D_SUCCESS –

Returns

A3D_SUCCESS in case of success or an error code