# A3DRWParamsTessellationData

struct `A3DRWParamsTessellationData`

  Describes the tessellation parameters.

  ## Index

  Variables

  - `m_eTessellationLevelOfDetail`
  - `m_dChordHeightRatio`
  - `m_dAngleToleranceDeg`
  - `m_dMaxChordHeight`
  - `m_bAccurateTessellation`
  - `m_bAccurateTessellationWithGrid`
  - `m_dAccurateTessellationWithGridMaximumStitchLength`
  - `m_bAccurateSurfaceCurvatures`
  - `m_bDoNotComputeNormalsInAccurateTessellation`
  - `m_bKeepUVPoints`
  - `m_bUseHeightInsteadOfRatio`
  - `m_dMaximalTriangleEdgeLength`

Variables

A3DETessellationLevelOfDetail `A3DRWParamsTessellationData.``m_eTessellationLevelOfDetail`
  `A3DETessellationLevelOfDetail`

  Enum to specify predefined values for some following members.

A3DDouble `A3DRWParamsTessellationData.``m_dChordHeightRatio`
  `A3DDouble`

  Specifies the ratio of the diagonal length of the bounding box to the chord height.

  A value of 50 means that the diagonal of the bounding box is 50 times greater than the chord height. Values can range from 50 to 10,000. Higher values will generate more accurate tessellation.

A3DDouble `A3DRWParamsTessellationData.``m_dAngleToleranceDeg`
  `A3DDouble`

  Specifies the maximum angle between two contiguous tessellation segments describing the curve of a topological edge for every face.

  During tessellation, the curve describing the edge of a topological face will be approximated using straight line segments. `m_dAngleToleranceDeg`is the maximum angle between two consecutive segments. Allowable values range from 10 to < 40. Lower values will result in greater accuracy.

A3DDouble `A3DRWParamsTessellationData.``m_dMaxChordHeight`
  `A3DDouble`

  Specifies the maximum distance between the original geometric surface specified in the CAD file and the resulting tessellation.

  Be careful, very small values can generate very large tessellation files. Conversely, very large values can generate inaccurate tessellation. In such cases, it may be better to use the `m_dChordHeightRatio`member to scale this value relative to the object that’s being tessellated.

  > `m_dMaxChordHeight`is ignored if `m_bUseHeightInsteadOfRatio`isn’t set to `A3D_TRUE`.

A3DBool `A3DRWParamsTessellationData.``m_bAccurateTessellation`
  `A3DBool`

  Accurate tessellation.

  Uses standard parameters. `A3D_FALSE`indicates the tessellation is set for visualization. Setting this value to `A3D_TRUE`will generate tessellation more suited for analysis. Can be used with all TessellationLevelOfDetails.

A3DBool `A3DRWParamsTessellationData.``m_bAccurateTessellationWithGrid`
  `A3DBool`

  Enables accurate tessellation with faces inner points on a grid.

A3DDouble `A3DRWParamsTessellationData.``m_dAccurateTessellationWithGridMaximumStitchLength`
  `A3DDouble`

  Maximal grid stitch length.

  Disabled if value is 0. Be careful, a too small value can generate a huge tessellation. Given in model units multiplied by the net scale of the Representation Item.

A3DBool `A3DRWParamsTessellationData.``m_bAccurateSurfaceCurvatures`
  `A3DBool`

  Takes into account surfaces curvature in accurate tessellation to control triangles elongation directions.

  Enable `m_bAccurateTessellation`or `m_bAccurateTessellationWithGrid`to use this option.

A3DBool `A3DRWParamsTessellationData.``m_bDoNotComputeNormalsInAccurateTessellation`
  `A3DBool`

  Do not compute surface normals in accurate tessellation.

  Enable `m_bAccurateTessellation`or `m_bAccurateTessellationWithGrid`to use this option.

A3DBool `A3DRWParamsTessellationData.``m_bKeepUVPoints`
  `A3DBool`

  Keep parametric points as texture points.

A3DBool `A3DRWParamsTessellationData.``m_bUseHeightInsteadOfRatio`
  `A3DBool`

  Use `m_dMaxChordHeight`instead of `m_dChordHeightRatio`if `m_eTessellationLevelOfDetail`= `kA3DTessLODUserDefined`.

A3DDouble `A3DRWParamsTessellationData.``m_dMaximalTriangleEdgeLength`
  `A3DDouble`

  Maximal length of the edges of triangles.

  Disabled if value is 0. Be careful, a too small value can generate a huge tessellation.

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