OGRE  13.6 Object-Oriented Graphics Rendering Engine
Ogre::RotationalSpline Class Reference

This class interpolates orientations (rotations) along a spline using derivatives of quaternions. More...

#include <OgreRotationalSpline.h>

## Public Member Functions

RotationalSpline ()

~RotationalSpline ()

Adds a control point to the end of the spline. More...

void clear (void)
Clears all the points in the spline. More...

unsigned short getNumPoints (void) const
Gets the number of control points in the spline. More...

const QuaterniongetPoint (unsigned short index) const
Gets the detail of one of the control points of the spline. More...

Quaternion interpolate (Real t, bool useShortestPath=true)
Returns an interpolated point based on a parametric value over the whole series. More...

Quaternion interpolate (unsigned int fromIndex, Real t, bool useShortestPath=true)
Interpolates a single segment of the spline given a parametric value. More...

void recalcTangents (void)
Recalculates the tangents associated with this spline. More...

void setAutoCalculate (bool autoCalc)
Tells the spline whether it should automatically calculate tangents on demand as points are added. More...

void updatePoint (unsigned short index, const Quaternion &value)
Updates a single point in the spline. More...

## Detailed Description

This class interpolates orientations (rotations) along a spline using derivatives of quaternions.

Like the SimpleSpline class, this class is about interpolating values smoothly over a spline. Whilst SimpleSpline deals with positions (the normal sense we think about splines), this class interpolates orientations. The theory is identical, except we're now in 4-dimensional space instead of 3.

In positional splines, we use the points and tangents on those points to generate control points for the spline. In this case, we use quaternions and derivatives of the quaternions (i.e. the rate and direction of change at each point). This is the same as SimpleSpline since a tangent is a derivative of a position. We effectively generate an extra quaternion in between each actual quaternion which when take with the original quaternion forms the 'tangent' of that quaternion.

## ◆ RotationalSpline()

 Ogre::RotationalSpline::RotationalSpline ( )

## ◆ ~RotationalSpline()

 Ogre::RotationalSpline::~RotationalSpline ( )

## Member Function Documentation

 void Ogre::RotationalSpline::addPoint ( const Quaternion & p )

Adds a control point to the end of the spline.

## ◆ getPoint()

 const Quaternion& Ogre::RotationalSpline::getPoint ( unsigned short index ) const

Gets the detail of one of the control points of the spline.

## ◆ getNumPoints()

 unsigned short Ogre::RotationalSpline::getNumPoints ( void ) const

Gets the number of control points in the spline.

## ◆ clear()

 void Ogre::RotationalSpline::clear ( void )

Clears all the points in the spline.

## ◆ updatePoint()

 void Ogre::RotationalSpline::updatePoint ( unsigned short index, const Quaternion & value )

Updates a single point in the spline.

This point must already exist in the spline.

## ◆ interpolate() [1/2]

 Quaternion Ogre::RotationalSpline::interpolate ( Real t, bool useShortestPath = true )

Returns an interpolated point based on a parametric value over the whole series.

Given a t value between 0 and 1 representing the parametric distance along the whole length of the spline, this method returns an interpolated point.

Parameters
 t Parametric value. useShortestPath Defines if rotation should take the shortest possible path

## ◆ interpolate() [2/2]

 Quaternion Ogre::RotationalSpline::interpolate ( unsigned int fromIndex, Real t, bool useShortestPath = true )

Interpolates a single segment of the spline given a parametric value.

Parameters
 fromIndex The point index to treat as t=0. fromIndex + 1 is deemed to be t=1 t Parametric value useShortestPath Defines if rotation should take the shortest possible path

## ◆ setAutoCalculate()

 void Ogre::RotationalSpline::setAutoCalculate ( bool autoCalc )

Tells the spline whether it should automatically calculate tangents on demand as points are added.

The spline calculates tangents at each point automatically based on the input points. Normally it does this every time a point changes. However, if you have a lot of points to add in one go, you probably don't want to incur this overhead and would prefer to defer the calculation until you are finished setting all the points. You can do this by calling this method with a parameter of 'false'. Just remember to manually call the recalcTangents method when you are done.

Parameters
 autoCalc If true, tangents are calculated for you whenever a point changes. If false, you must call reclacTangents to recalculate them when it best suits.

## ◆ recalcTangents()

 void Ogre::RotationalSpline::recalcTangents ( void )

Recalculates the tangents associated with this spline.

If you tell the spline not to update on demand by calling setAutoCalculate(false) then you must call this after completing your updates to the spline points.

The documentation for this class was generated from the following file: