This object stores the read-only data of an IPO. More...

Public Types
enum	{ IP_CONST , IP_LINEAR , IP_BEZIER }
	The three interpolations defined by blender.

enum	{ ET_CONST , ET_EXTRAP , ET_CYCLIC_EXTRAP , ET_CYCLIC }
	The four extend types.

Public Member Functions
	IpoData (const XMLNode &curve, float fps, bool reverse)
	Initialise the Ipo from the specifications in the XML file.

void	readCurve (const XMLNode &node, bool reverse)
	Reads in 3 dimensional curve data - i.e.

void	readIPO (const XMLNode &node, float fps, bool reverse)
	Reads a blender IPO curve, which constists of a frame number and a control point.

float	approximateLength (float t0, float t1, const Vec3 &p0, const Vec3 &p1, const Vec3 &h1, const Vec3 &h2)
	Approximates the length of a bezier curve using a simple Euler approximation by dividing the interval [t0, t1] into 10 pieces.

float	adjustTime (float time)
	Adjusts the time so that it is between start and end of this Ipo.

float	get (float time, unsigned int index, unsigned int n)

float	getDerivative (float time, unsigned int index, unsigned int n)
	Determines the derivative of a IPO at a given point.

Public Attributes
IpoChannelType	m_channel
	The type of this IPO.

enum Ipo::IpoData:: { ... }	m_interpolation
	The three interpolations defined by blender.

enum Ipo::IpoData:: { ... }	m_extend
	The four extend types.

std::vector< Vec3 >	m_points
	The actual control points.

std::vector< Vec3 >	m_handle1
	Only used for bezier curves: the two handles.

std::vector< Vec3 >	m_handle2

float	m_start_time
	Time of the first control point.

float	m_end_time
	Time of the last control point.

Vec3	m_initial_xyz
	Stores the inital position of the object.

Vec3	m_initial_hpr
	Stores the inital rotation of the object.

Private Member Functions
float	getCubicBezier (float t, float p0, float p1, float p2, float p3) const
	Computes a cubic bezier curve for a given t in [0,1] and four control points.

float	getCubicBezierDerivative (float t, float p0, float p1, float p2, float p3) const
	Returns the derivative of a cubic bezier curve for a given t in [0,1] and four control points.

void	approximateBezier (float t0, float t1, const Vec3 &p0, const Vec3 &p1, const Vec3 &h0, const Vec3 &h2, unsigned int rec_level=0)
	This function approximates a bezier curve by piecewise linear functions.

Detailed Description

This object stores the read-only data of an IPO.

It might be shared among several instances of an Ipo (e.g. in a cannon animation).

Constructor & Destructor Documentation

◆ IpoData()

Ipo::IpoData::IpoData	(	const XMLNode &	curve,
		float	fps,
		bool	reverse
	)

Initialise the Ipo from the specifications in the XML file.

Parameters

curve	The XML node with the IPO data.
fps	Frames per second value, necessary to convert frame values into time.
reverse	If this is set to true, the ipo data will be reverse. This is used by the cannon if the track is driven in reverse.

Member Function Documentation

◆ adjustTime()

float Ipo::IpoData::adjustTime ( float time )

Adjusts the time so that it is between start and end of this Ipo.

This takes the extend type into account, e.g. cyclic animations will just use a modulo operation, while constant extends will return start or end time directly.

Parameters

time	The time to adjust.

◆ approximateBezier()

void Ipo::IpoData::approximateBezier	(	float	t0,
		float	t1,
		const Vec3 &	p0,
		const Vec3 &	p1,
		const Vec3 &	h0,
		const Vec3 &	h1,
		unsigned int	rec_level = `0`
	)

private

This function approximates a bezier curve by piecewise linear functions.

It uses quite primitive approximations: if the estimated distance of the bezier curve at between t=t0 and t=t1 is greater than 2, it inserts one point at (t0+t1)/2, and recursively splits the two intervals further. End condition is either a maximum recursion depth of 6 or an estimated curve length of less than 2. It does not add any points at t=t0 or t=t1, only between this interval.

Parameters

t0,t1	The interval which is approximated.
p0,p1,h0,h1	The bezier parameters.
rec_level	The recursion level to avoid creating too many points.

◆ approximateLength()

float Ipo::IpoData::approximateLength	(	float	t0,
		float	t1,
		const Vec3 &	p0,
		const Vec3 &	p1,
		const Vec3 &	h0,
		const Vec3 &	h1
	)

Approximates the length of a bezier curve using a simple Euler approximation by dividing the interval [t0, t1] into 10 pieces.

Good enough for our needs in STK.

Parameters

t0,t1	Approximate for t in [t0, t1].
p0,p1	The start and end point of the curve.
h0,h1	The control points for the corresponding points.

◆ getCubicBezier()

float Ipo::IpoData::getCubicBezier	(	float	t,
		float	p0,
		float	p1,
		float	p2,
		float	p3
	)		const

private

Computes a cubic bezier curve for a given t in [0,1] and four control points.

The curve will go through p0 (t=0), p3 (t=1).

Parameters

t	The parameter for the bezier curve, must be in [0,1].
p0,p1,p2,p3	The four control points.

◆ getCubicBezierDerivative()

float Ipo::IpoData::getCubicBezierDerivative	(	float	t,
		float	p0,
		float	p1,
		float	p2,
		float	p3
	)		const

private

Returns the derivative of a cubic bezier curve for a given t in [0,1] and four control points.

The curve will go through p0 (t=0).

Parameters

t	The parameter for the bezier curve, must be in [0,1].
p0,p1,p2,p3	The four control points.

◆ getDerivative()

float Ipo::IpoData::getDerivative	(	float	time,
		unsigned int	index,
		unsigned int	n
	)

Determines the derivative of a IPO at a given point.

Parameters

time	At what time value the derivative is to be computed.
index	IpoData is based on 3d data. The index specified which value to use (0=x, 1=y, 2=z).
n	Curve segment to be used for the computation. It must be correct for the specified time value.

◆ readCurve()

void Ipo::IpoData::readCurve	(	const XMLNode &	curve,
		bool	reverse
	)

Reads in 3 dimensional curve data - i.e.

the xml file contains xyz, but no time. If the curve is using bezier interpolation, the curve is approximated by piecewise linear functions. Reason is that bezier curves can not (easily) be used for smooth (i.e. constant speed) driving: A linear time variation in [0, 1] will result in non-linear distances for the bezier function, which is a 3rd degree polynomial (--> the speed which is the deviation of this function is a 2nd degree polynomial, and therefore not constant!

Parameters

node	The root node with all curve data points.
reverse	If this is set, the data are read in reverse. This is used for a cannon in reverse mode.

◆ readIPO()

void Ipo::IpoData::readIPO	(	const XMLNode &	curve,
		float	fps,
		bool	reverse
	)

Reads a blender IPO curve, which constists of a frame number and a control point.

This only handles a single axis.

Parameters

node	The root node with all curve data points.
fps	Frames per second value, necessary to convert the frame based data from blender into times.
reverse	If this is set, the data are read in reverse. This is used for a cannon in reverse mode.

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

animations/ipo.hpp
animations/ipo.cpp

Public Types

Public Member Functions

Public Attributes

Private Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ IpoData()

Member Function Documentation

◆ adjustTime()

◆ approximateBezier()

◆ approximateLength()

◆ getCubicBezier()

◆ getCubicBezierDerivative()

◆ getDerivative()

◆ readCurve()

◆ readIPO()