API Reference > geometry-core > Serialization > IModelJson > IModelJson.TransitionSpiralProps IModelJson.TransitionSpiralProps Interface Interface for spiral Any 4 (but not 5) of the 5 values [startBearing, endBearing, startRadius, endRadius, length] may be defined. In radius data, zero radius indicates straight line (infinite radius) Note that the inherited AxesProps allows multiple ways to specify orientation of the placement.. Extends IModelJson.AxesProps Properties Name Type Description curveLength undefined | number length along curve endBearing undefined | AngleProps End bearing. endRadius undefined | number Radius at end (0 for straight line) fractionInterval undefined | number[] Fractional part of active interval. intervalFractions undefined | [number, number] A fractional portion of the spiral may be selected. origin XYZProps origin of the coordinate system. startBearing undefined | AngleProps angle at departure from origin. startRadius undefined | number Radius at start (0 for straight line) type undefined | string TransitionSpiral type. Inherited properties Name Type Inherited from Description xyVectors undefined | [XYZProps, XYZProps] IModelJson.AxesProps Cartesian coordinate directions defined by X direction then Y direction. yawPitchRollAngles undefined | YawPitchRollProps IModelJson.AxesProps See YawPitchAngles class for further information about using 3 rotations to specify orientation. zxVectors undefined | [XYZProps, XYZProps] IModelJson.AxesProps Cartesian coordinate directions defined by X direction then Y direction. Defined in core/geometry/src/serialization/IModelJsonSchema.ts Line 311 Last Updated: 13 June, 2024