# CurveTangent Enumeration

**Namespace:**Microsoft.Xna.Framework

**Assembly:**Microsoft.Xna.Framework.Math (in Microsoft.Xna.Framework.Math.dll)

Member name | Description | |
---|---|---|

Flat | A Flat tangent always has a value equal to zero. | |

Linear | A Linear tangent at a CurveKey is equal to the difference between its Value and the value of the preceding or succeeding CurveKey. | |

Smooth | A Smooth tangent smooths the inflection between a TangentIn and TangentOut by taking into account the values of both neighbors of the CurveKey. |

A Linear tangent at a CurveKey is equal to the difference between its Value and the value of the preceding or succeeding CurveKey.

For example, in Curve MyCurve, where i is greater than zero and (i + 1) is less than the total number of CurveKey instances in MyCurve, the linear TangentIn of MyCurve.Keys[i] is equal to:

( MyCurve.Keys[i].Value - MyCurve.Keys[i - 1].Value )

Similarly, the linear TangentOut is equal to:

( MyCurve.Keys[i + 1].Value - MyCurve.Keys[i].Value.)

A Smooth tangent smooths the inflection between a TangentIn and TangentOut by taking into account the values of both neighbors of the CurveKey.

The smooth TangentIn of MyCurve.Keys[i] is equal to:

( ( MyCurve.Keys[i + 1].Value - MyCurve.Keys[i - 1].Value ) *

( ( MyCurve.Keys[i].Position - MyCurve.Keys[i - 1].Position ) /

( MyCurve.Keys[i + 1].Position - MyCurve.Keys[i-1].Position ) ) )

Similarly, the smooth TangentOut is equal to:

( ( MyCurve.Keys[i + 1].Value - MyCurve.Keys[i - 1].Value ) *

( ( MyCurve.Keys[i + 1].Position - MyCurve.Keys[i].Position ) /

( MyCurve.Keys[i + 1].Position - MyCurve.Keys[i - 1].Position ) ) )

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