HeightFieldSediment Class Reference

A height field with one sediment (sand) layer. More...

#include <heightfieldsediment.h>

Inheritance diagram for HeightFieldSediment:

Public Member Functions
	HeightFieldSediment ()
	Create an empty terrain.
	HeightFieldSediment (const Box2 &, int, int)
	Create a flat terrain with no sediments.
	HeightFieldSediment (const ScalarField2 &)
	Create a terrain with no sediments from an elevation field.
	HeightFieldSediment (const ScalarField2 &, const ScalarField2 &)
	Create a terrain with sediments.
	~HeightFieldSediment ()
	Empty.
Array2	GetArray () const
	Return the array representing the grid domain.
ScalarField2	AlphaBlend () const
	Compute the alpha blending between sand and bedrock.
HeightField	GetHeightField () const
	Convert the layered model into a simple heightfield.
bool	Intersect (const Ray &, double &, Vector &) const
	Compute the intersection between a ray and the surface of the terrain.
void	SmoothRock (int=1)
	Smoothes the bedrock layer.
HeightField &	GetBedrock ()
	Access to the bedrock scalar field.
ScalarField2 &	GetSand ()
	Access to the sand scalar field.
double	Bedrock (const Vector2 &) const
	Compute the bedrock elevation.
double	Bedrock (int, int) const
	Return the bedrock elevation.
double	Sand (const Vector2 &) const
	Compute the sand thickness.
double	Sand (int, int) const
	Return the sand thickness.
void	Subdivide ()
	Double the resolution of the terrain.
void	BedrockFlatten (const Vector2 &, const double &, const double &=0.25)
	Flatten the bedrock around the target point.
void	BedrockLevel (const Vector2 &, const double &, const double &)
	Level the bedrock to the target elevation.
void	BedrockUplift (const double &)
	Modify the bedrock using a uniform uplift.
void	BedrockUplift (const ScalarField2 &)
	Uplift.
void	ThermalImpact (const double &)
	Globally transform a thin layer of bedrock into sediments.
void	ThermalImpactSlope (const double &)
	Globally transform a thin layer of bedrock into sediments.
void	Stabilize (const double &, const double &=0.84)
	Stabilizes sediments over the entire terrain.
bool	StabilizeStep (int, int, const double &, ScalarField2 &)
	Perform a stabilization step on the given layered cell.
int	CheckFlowSlope (const QPoint &, FlowStruct &) const
	Compute the flow directions at a given point.
int	CheckFlowDirectionsAngle (const QPoint &, const double &, QPoint *, double *, double *, double *) const
	Compute the flow directions at a given point.
bool	SelectFlowDirection (const QPoint &, QPoint &, double &) const
	Select flow direction.
void	TRUC (const QPoint &q, const double &slope, const double &V_T, double &V_T_S, double &V_E_R, double &V_E_S, double &V_D_S)
	Compute eroded material.

Protected Member Functions
void	Evaporate (const double &, const double &, double &, double &, double &)
	Evaporate some water from the droplet.

Protected Attributes
HeightField	bedrock
	Bedrock.
ScalarField2	sand
	Sand, i.e., sediments.

Detailed Description

A height field with one sediment (sand) layer.

Constructor & Destructor Documentation

HeightFieldSediment() [1/3]

HeightFieldSediment::HeightFieldSediment ( const Box2 & box, int nx, int ny )

explicit

Create a flat terrain with no sediments.

Parameters

nx,ny	Subdivision of the terrain.
box	Rectangular domain.

HeightFieldSediment() [2/3]

HeightFieldSediment::HeightFieldSediment

(

const ScalarField2 &

b

)

Create a terrain with no sediments from an elevation field.

Parameters

b

Bedrock.

HeightFieldSediment() [3/3]

HeightFieldSediment::HeightFieldSediment ( const ScalarField2 & b, const ScalarField2 & s )

explicit

Create a terrain with sediments.

Parameters

b	Bedrock.
s	Sediments.

Member Function Documentation

Bedrock() [1/2]

double HeightFieldSediment::Bedrock ( const Vector2 & p ) const

inline

Compute the bedrock elevation.

Parameters

p

Point.

Bedrock() [2/2]

double HeightFieldSediment::Bedrock ( int i, int j ) const

inline

Return the bedrock elevation.

Parameters

i,j	Integer coordinates.

BedrockFlatten()

void HeightFieldSediment::BedrockFlatten	(	const Vector2 &	c,
		const double &	r,
		const double &	s = 0.25 )

Flatten the bedrock around the target point.

The neighboring elevation should converge to the terrain level at target point.

Parameters

c	Center.
r	Radius.
s	Scaling of the effect.

BedrockLevel()

void HeightFieldSediment::BedrockLevel	(	const Vector2 &	c,
		const double &	r,
		const double &	z )

Level the bedrock to the target elevation.

Parameters

c	Center.
r	Radius.
z	Elevation.

BedrockUplift() [1/2]

void HeightFieldSediment::BedrockUplift

(

const double &

u

)

Modify the bedrock using a uniform uplift.

Parameters

u	Constant ulift.

BedrockUplift() [2/2]

void HeightFieldSediment::BedrockUplift

(

const ScalarField2 &

u

)

Uplift.

Parameters

u	Uplift scalar field.

CheckFlowDirectionsAngle()

int HeightFieldSediment::CheckFlowDirectionsAngle	(	const QPoint &	p,
		const double &	s,
		QPoint *	point,
		double *	height,
		double *	slope,
		double *	nslope ) const

Compute the flow directions at a given point.

Parameters

p	Point.
s	Slope, i.e. tangent of repose angle.
point	Array of neighboring points.
height	Array of height difference
slope	Array of slopes.
nslope	Array of normalized slopes.

CheckFlowSlope()

int HeightFieldSediment::CheckFlowSlope	(	const QPoint &	p,
		FlowStruct &	flow ) const

Compute the flow directions at a given point.

Parameters

p	Point.
flow	Flow information.

Intersect()

bool HeightFieldSediment::Intersect	(	const Ray &	ray,
		double &	t,
		Vector &	q ) const

Compute the intersection between a ray and the surface of the terrain.

The algorithm uses a ray marching approach, therefore this function may require many iterations and the resulting intersection may not be accurate.

Parameters

ray	The ray.
t	Intersection depth.
q	Intersection point.

Sand() [1/2]

double HeightFieldSediment::Sand ( const Vector2 & p ) const

inline

Compute the sand thickness.

Parameters

p

Point.

Sand() [2/2]

double HeightFieldSediment::Sand ( int i, int j ) const

inline

Return the sand thickness.

Parameters

i,j	Integer coordinates.

SelectFlowDirection()

bool HeightFieldSediment::SelectFlowDirection	(	const QPoint &	a,
		QPoint &	b,
		double &	slope ) const

Select flow direction.

Compute the different flow directions and perform a random selection among candidates.

Parameters

a	Cell.
b	Returned neighboring cell.
slope	Returned slope.

SmoothRock()

void HeightFieldSediment::SmoothRock

(

int

n = 1

)

Smoothes the bedrock layer.

Parameters

n	Number of iterations.

Stabilize()

void HeightFieldSediment::Stabilize	(	const double &	e,
		const double &	sar = 0.84 )

Stabilizes sediments over the entire terrain.

This is a an optimized algorithm with an internal queue to handle only the relevant unstable stacks during the stabilization process.

Parameters

e	Elevation of sediments transported at every step of the algorithm.
sar	Slope corresponding to the critical angle of repose, by default tan(40°) ~ 0.84.

Without optimization, the brute force stabilization algorithm may be implemented as follows:

bool stabilized = false;
int iterations = 0;
 
ScalarField2 moved(Box2(a, b), nx, ny, 0.0);
ScalarField2 deltaSand(Box2(a, b), nx, ny);
 
while (!stabilized && (iterations < n))
{
stabilized = true;
 
deltaSand.Fill(0.0);
for (int i = 0; i < nx; i++)
{
for (int j = 0; j < ny; j++)
{
bool flag = StabilizeStep(i, j, e, deltaSand);
stabilized &= flag;
}
}
sand+=(deltaSand);
deltaSand.Abs();
moved+=(deltaSand);
iterations++;

StabilizeStep()

bool HeightFieldSediment::StabilizeStep	(	int	x,
		int	y,
		const double &	eee,
		ScalarField2 &	deltaSand )

Perform a stabilization step on the given layered cell.

Returns

true if the cell was stable, false otherwise.

ThermalImpact()

void HeightFieldSediment::ThermalImpact

(

const double &

s

)

Globally transform a thin layer of bedrock into sediments.

Parameters

s	Thickness (in meters).

ThermalImpactSlope()

void HeightFieldSediment::ThermalImpactSlope

(

const double &

s

)

Globally transform a thin layer of bedrock into sediments.

Parameters

s	Thickness (in meters).