CVectorField Class Reference

A vector field. More...

#include <VectorField.h>

Inheritance diagram for CVectorField:

Collaboration diagram for CVectorField:

Public Member Functions
	CVectorField (UINT)
	Constructor.
	~CVectorField ()
	Destructor.
void	Clear ()
	Clear.
void	Draw ()
	Draw.
void	Update (const Vector2 &, const Vector2 &)
	Update pressures around moving object.
void	Detonate (const Vector2 &)
	Detonation.
void	Step (const UINT n)
	Perform an animation step.
const Vector2	GetClosestVector (const Vector2 &) const
	Get vector closest to a point.

Private Member Functions
const bool	GetClosestVertex (const Vector2 &, UINT &, UINT &) const
	Closest vertex.
const bool	isInternalVertex (UINT, UINT) const
	Check that indices are for a non-edge vertex.
const float	GetAveragePressure (UINT, UINT) const
	Average pressure around a vertex.
const Vector2	GetVectorFromPressure (UINT, UINT) const
	Average vectors around a vertex.
void	Update (UINT, UINT, UINT, float)
	Update pressures around moving object.
void	RelaxPressure (const UINT)
	Relax pressure at the vertices.
void	DrawVectors ()
	Draw vectors.
void	DrawPoints ()
	Draw points.
void	DrawPressures ()
	Draw pressures.

Private Attributes
CVertex **	m_pVertex = nullptr
	2D array of vertices.
UINT	m_nWidth = 0
	Number of vertices wide.
UINT	m_nHeight = 0
	Number of vertices high.
float	m_fDelta = 0.0f
	Spacing between vertices in Render World units.

Additional Inherited Members
Static Protected Attributes inherited from CCommon
static b2World *	m_pPhysicsWorld = nullptr
	Pointer to Box2D Physics World.
static CBox2DRenderer *	m_pRenderer = nullptr
	Pointer to renderer.
static CObjectManager *	m_pObjectManager = nullptr
	Pointer to the object manager.
static Sage::CParticleEngine2D *	m_pParticleEngine = nullptr
	Pointer to particle engine.
static CVectorField *	m_pVectorField = nullptr
	Pointer to a vector field.
static CBubbleEngine *	m_pBubbleEngine = nullptr
	Pointer to a bubble engine.
static bool	m_bDrawVectors = false
	Do we draw the vector field?
static bool	m_bDrawPressure = false
	Do we draw the pressures from the vector field?
static bool	m_bDrawPoints = false
	Do we draw the points from the vector field?
static bool	m_bDrawParticles = true
	Do we draw particles?
static eWordColor	m_eCurColor = eWordColor::Black
	Color of the current word.
static bool	m_bTried = false
	Whether the player has tried on the current word.
static UINT	m_nWordCnt = INITIAL_WORDCOUNT
	Number of words.
static int	m_nScore = 0
	Current score, can be negative.
static int	m_nDelivered = 0
	Number of words delivered.
static int	m_nExcellent = 0
	Number of words scored as excellent.
static int	m_nGood = 0
	Number of words scored as excellent.
static int	m_nFair = 0
	Number of words scored as excellent.
static int	m_nFailed = 0
	Number of words the player got wrong.
static int	m_nMissed = 0
	Number of words the player did not attempt.
static eGameState	m_eGameState = eGameState::Loading
	Current game state.
static UINT	m_nCntdownNum = 0
	The number we are displaying in the countdown.
static CStroop *	m_pStroop = nullptr
	Pointer to Stroop caricature.
static eDrawMode	m_eDrawMode = eDrawMode::Sprites
	Draw mode.

Detailed Description

Our vector field consists of an evenly-spaced grid of points. At each point there is a vector and a pressure. The pressure is the magnitude of the vertex at that point.

Constructor & Destructor Documentation

CVectorField()

CVectorField::CVectorField

(

UINT

n

)

Create a vector field with a given number of vertices horizontally. The vertices will be spaced out evenly horizontally. The vertical spacing will be the same as the horizontal spacing, and as many rows of vertices as fits into the window will be used.

Parameters

n	Number of vertices across the window.

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Member Function Documentation

Clear()

void CVectorField::Clear

(

)

Set all of the vectors and pressures to zero, and mark all vertices as unoccupied.

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Detonate()

void CVectorField::Detonate

(

const Vector2 &

p

)

Add vectors acting outwards from a point. Eight vectors are added, horizontal, vertical,diagonal, and back-diagonal. The magnitude of the diagonal and back-diagonal vectors are divided by sqrt(2).

Parameters

p

A point.

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Draw()

void CVectorField::Draw

(

)

Draw the vector field points, vectors and pressures as directed by the corresponding Boolean member variables.

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DrawPoints()

void CVectorField::DrawPoints ( )

private

Draw the vector field points.

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DrawPressures()

void CVectorField::DrawPressures ( )

private

Draw pressures as light and dark squares.

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DrawVectors()

void CVectorField::DrawVectors ( )

private

Draw the vectors as scaled arrows.

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GetAveragePressure()

const float CVectorField::GetAveragePressure ( UINT i, UINT j ) const

private

Compute the average pressure of 8 neighboring vertices weighted by distance. This does not include the center vertex.

Parameters

i	Row number of vertex.
j	Column number of vertex.

Returns

Average pressure around vertex.

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GetClosestVector()

const Vector2 CVectorField::GetClosestVector

(

const Vector2 &

p

)

const

Get the vector acting on a point by the vector field.

Parameters

p

A point.

Returns

The vector acting on p.

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GetClosestVertex()

const bool CVectorField::GetClosestVertex ( const Vector2 & p, UINT & i, UINT & j ) const

private

Find the horizontal and vertical indices of the closest vertex.

Parameters

p	A point.
i	[OUT] Vertical index.
j	[OUT] Horizontal index.

Returns

true if the indices are without range, false for failure.

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GetVectorFromPressure()

const Vector2 CVectorField::GetVectorFromPressure ( UINT i, UINT j ) const

private

Compute the average vector of 8 neighboring vertices based on pressure, weighted by distance. This does not include the center vertex.

Parameters

i	Row index of vertex.
j	Column index of vertex.

Returns

Average of the eight neighbors of vertex.

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isInternalVertex()

const bool CVectorField::isInternalVertex ( UINT i, UINT j ) const

private

A vertex is isInternalVertex if it is in range and not an edge vertex.

Parameters

i	Row index.
j	Column index.

Returns

true if vertex [i][j] is in range and not an edge vertex.

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RelaxPressure()

void CVectorField::RelaxPressure ( const UINT n )

private

Relax the pressure at each vertex by lerping it towards the weighted average of the pressures of its neighbors. The weights are Euclidean distances, that is, diagonal neighbors are weighted by \(\sqrt{2}\) while the others are weighted \(1\).

Parameters

n	Number of iterations of Gauss-Seidel relaxation.

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Step()

void CVectorField::Step

(

const UINT

n

)

Relax the pressures, update the vectors, and mark all vertices unoccupied. Vectors at each vertex are lerped with the average of the vectors from its neighbors.

Parameters

n	Number of iterations of relaxation.

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Update() [1/2]

void CVectorField::Update	(	const Vector2 &	p,
		const Vector2 &	v )

Update the pressures due to a moving point. Pressure increases ahead of the point and decrases behind it. Since each vertex can be updated only once per step, increases are done before decreases.

Parameters

p	Position of moving point.
v	Velocity of moving point.

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Update() [2/2]

void CVectorField::Update ( UINT i, UINT j, UINT r, float p )

private

The pressures around a vertex are lerped towards new values. The lerp fraction is hard-coded. Each vertex can be updated only once per step, so make sure that the important ones get done first.

Parameters

i	Row index.
j	Column index.
r	Effect radius.
p	New pressure.

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