vtkLightKit Class Reference

#include <vtkLightKit.h>

Inheritance diagram for vtkLightKit:

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Collaboration diagram for vtkLightKit:

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List of all members.

Detailed Description

a simple but quality lighting kit

vtkLightKit is designed to make general purpose lighting of vtk scenes simple, flexible, and attractive (or at least not horribly ugly without significant effort). Use a LightKit when you want more control over your lighting than you can get with the default vtk light, which is a headlight located at the camera. (HeadLights are very simple to use, but they don't show the shape of objects very well, don't give a good sense of "up" and "down", and don't evenly light the object.)

A LightKit consists of three lights, a key light, a fill light, and a headlight. The main light is the key light. It is usually positioned so that it appears like an overhead light (like the sun, or a ceiling light). It is generally positioned to shine down on the scene from about a 45 degree angle vertically and at least a little offset side to side. The key light usually at least about twice as bright as the total of all other lights in the scene to provide good modeling of object features.

The other lights in the kit (the fill light, headlight, and a pair of back lights) are weaker sources that provide extra illumination to fill in the spots that the key light misses. The fill light is usually positioned across from or opposite from the key light (though still on the same side of the object as the camera) in order to simulate diffuse reflections from other objects in the scene. The headlight, always located at the position of the camera, reduces the contrast between areas lit by the key and fill light. The two back lights, one on the left of the object as seen from the observer and one on the right, fill on the high-contrast areas behind the object. To enforce the relationship between the different lights, the intensity of the fill, back and headlights are set as a ratio to the key light brightness. Thus, the brightness of all the lights in the scene can be changed by changing the key light intensity.

All lights are directional lights (infinitely far away with no falloff). Lights move with the camera.

For simplicity, the position of lights in the LightKit can only be specified using angles: the elevation (latitude) and azimuth (longitude) of each light with respect to the camera, expressed in degrees. (Lights always shine on the camera's lookat point.) For example, a light at (elevation=0, azimuth=0) is located at the camera (a headlight). A light at (elevation=90, azimuth=0) is above the lookat point, shining down. Negative azimuth values move the lights clockwise as seen above, positive values counter-clockwise. So, a light at (elevation=45, azimuth=-20) is above and in front of the object and shining slightly from the left side.

vtkLightKit limits the colors that can be assigned to any light to those of incandescent sources such as light bulbs and sunlight. It defines a special color spectrum called "warmth" from which light colors can be chosen, where 0 is cold blue, 0.5 is neutral white, and 1 is deep sunset red. Colors close to 0.5 are "cool whites" and "warm whites," respectively.

Since colors far from white on the warmth scale appear less bright, key-to-fill and key-to-headlight ratios are skewed by key, fill, and headlight colors. If the flag MaintainLuminance is set, vtkLightKit will attempt to compensate for these perceptual differences by increasing the brightness of more saturated colors.

A LightKit is not explicitly part of the vtk pipeline. Rather, it is a composite object that controls the behavior of lights using a unified user interface. Every time a parameter of vtkLightKit is adjusted, the properties of its lights are modified.

Credits:: vtkLightKit was originally written and contributed to vtk by Michael Halle (mhalle@bwh.harvard.edu) at the Surgical Planning Lab, Brigham and Women's Hospital.

Examples:: vtkLightKit (Examples)

Definition at line 103 of file vtkLightKit.h.


Public Types
enum	LightKitType { TKeyLight, TFillLight, TBackLight, THeadLight }
enum	LightKitSubType { Warmth, Intensity, Elevation, Azimuth, KFRatio, KBRatio, KHRatio }
typedef vtkObject	Superclass
Public Member Functions
virtual const char *	GetClassName ()
virtual int	IsA (const char *type)
void	PrintSelf (ostream &os, vtkIndent indent)
virtual void	SetFillLightWarmth (double)
virtual double	GetFillLightWarmth ()
virtual void	SetHeadLightWarmth (double)
virtual double	GetHeadLightWarmth ()
virtual void	SetBackLightWarmth (double)
virtual double	GetBackLightWarmth ()
void	SetKeyLightElevation (double x)
void	SetKeyLightAzimuth (double x)
virtual double *	GetKeyLightAngle ()
virtual void	GetKeyLightAngle (double data[2])
double	GetKeyLightElevation ()
double	GetKeyLightAzimuth ()
void	SetFillLightAngle (double elevation, double azimuth)
void	SetFillLightAngle (double angle[2])
void	SetFillLightElevation (double x)
void	SetFillLightAzimuth (double x)
virtual double *	GetFillLightAngle ()
virtual void	GetFillLightAngle (double data[2])
double	GetFillLightElevation ()
double	GetFillLightAzimuth ()
void	SetBackLightAngle (double elevation, double azimuth)
void	SetBackLightAngle (double angle[2])
void	SetBackLightElevation (double x)
void	SetBackLightAzimuth (double x)
virtual double *	GetBackLightAngle ()
virtual void	GetBackLightAngle (double data[2])
double	GetBackLightElevation ()
double	GetBackLightAzimuth ()
void	DeepCopy (vtkLightKit *kit)
void	Modified ()
void	Update ()

virtual void	SetKeyLightIntensity (double)
virtual double	GetKeyLightIntensity ()

virtual void	SetKeyToFillRatio (double)
virtual double	GetKeyToFillRatio ()

virtual void	SetKeyToHeadRatio (double)
virtual double	GetKeyToHeadRatio ()

virtual void	SetKeyToBackRatio (double)
virtual double	GetKeyToBackRatio ()

virtual void	SetKeyLightWarmth (double)
virtual double	GetKeyLightWarmth ()

virtual double *	GetKeyLightColor ()
virtual void	GetKeyLightColor (double data[3])
virtual double *	GetFillLightColor ()
virtual void	GetFillLightColor (double data[3])
virtual double *	GetHeadLightColor ()
virtual void	GetHeadLightColor (double data[3])
virtual double *	GetBackLightColor ()
virtual void	GetBackLightColor (double data[3])

void	SetHeadlightWarmth (double v)
double	GetHeadlightWarmth ()
void	GetHeadlightColor (double *color)

virtual void	MaintainLuminanceOn ()
virtual void	MaintainLuminanceOff ()
virtual int	GetMaintainLuminance ()
virtual void	SetMaintainLuminance (int)

void	SetKeyLightAngle (double elevation, double azimuth)
void	SetKeyLightAngle (double angle[2])

void	AddLightsToRenderer (vtkRenderer *renderer)
void	RemoveLightsFromRenderer (vtkRenderer *renderer)
Static Public Member Functions
static vtkLightKit *	New ()
static int	IsTypeOf (const char *type)
static vtkLightKit *	SafeDownCast (vtkObject *o)
static const char *	GetStringFromType (int type)
static const char *	GetStringFromSubType (int type)
static const char *	GetShortStringFromSubType (int subtype)
static LightKitSubType	GetSubType (LightKitType type, int i)
Protected Member Functions
	vtkLightKit ()
	~vtkLightKit ()
void	WarmthToRGBI (double w, double rgb[3], double &i)
void	WarmthToRGB (double w, double rgb[3])
void	InitializeWarmthFunctions ()
double	WarmthToIntensity (double w)
Protected Attributes
double	KeyLightIntensity
double	KeyToFillRatio
double	KeyToHeadRatio
double	KeyToBackRatio
vtkLight *	KeyLight
double	KeyLightWarmth
double	KeyLightAngle [2]
double	KeyLightColor [3]
vtkLight *	FillLight
double	FillLightWarmth
double	FillLightAngle [2]
double	FillLightColor [3]
double	BackLightWarmth
double	BackLightColor [3]
vtkLight *	BackLight0
vtkLight *	BackLight1
double	BackLightAngle [2]
vtkLight *	HeadLight
double	HeadLightWarmth
double	HeadLightColor [3]
int	MaintainLuminance
vtkPiecewiseFunction *	WarmthFunction [4]

Member Typedef Documentation

typedef vtkObject vtkLightKit::Superclass

Reimplemented from vtkObject.

Definition at line 107 of file vtkLightKit.h.

Member Enumeration Documentation

enum vtkLightKit::LightKitType

Enumerator:

TKeyLight
TFillLight
TBackLight
THeadLight

Definition at line 111 of file vtkLightKit.h.

enum vtkLightKit::LightKitSubType

Enumerator:

Warmth
Intensity
Elevation
Azimuth
KFRatio
KBRatio
KHRatio

Definition at line 118 of file vtkLightKit.h.

Constructor & Destructor Documentation

vtkLightKit::vtkLightKit ( ) [protected]

vtkLightKit::~vtkLightKit ( ) [protected]

Member Function Documentation

static vtkLightKit* vtkLightKit::New ( ) [static]

Create an object with Debug turned off, modified time initialized to zero, and reference counting on.

Reimplemented from vtkObject.

virtual const char* vtkLightKit::GetClassName ( ) [virtual]

Reimplemented from vtkObject.

static int vtkLightKit::IsTypeOf ( const char * name ) [static]

Return 1 if this class type is the same type of (or a subclass of) the named class. Returns 0 otherwise. This method works in combination with vtkTypeRevisionMacro found in vtkSetGet.h.

Reimplemented from vtkObject.

virtual int vtkLightKit::IsA ( const char * name ) [virtual]

Return 1 if this class is the same type of (or a subclass of) the named class. Returns 0 otherwise. This method works in combination with vtkTypeRevisionMacro found in vtkSetGet.h.

Reimplemented from vtkObject.

static vtkLightKit* vtkLightKit::SafeDownCast ( vtkObject * o ) [static]

Reimplemented from vtkObject.

void vtkLightKit::PrintSelf	(	ostream &	os,
		vtkIndent	indent
	)			`[virtual]`

Methods invoked by print to print information about the object including superclasses. Typically not called by the user (use Print() instead) but used in the hierarchical print process to combine the output of several classes.

Reimplemented from vtkObject.

virtual void vtkLightKit::SetKeyLightIntensity ( double ) [virtual]

Set/Get the intensity of the key light. The key light is the brightest light in the scene. The intensities of the other two lights are ratios of the key light's intensity.

virtual double vtkLightKit::GetKeyLightIntensity ( ) [virtual]

Set/Get the intensity of the key light. The key light is the brightest light in the scene. The intensities of the other two lights are ratios of the key light's intensity.

virtual void vtkLightKit::SetKeyToFillRatio ( double ) [virtual]

Set/Get the key-to-fill ratio. This ratio controls how bright the fill light is compared to the key light: larger values correspond to a dimmer fill light. The purpose of the fill light is to light parts of the object not lit by the key light, while still maintaining constrast. This type of lighting may correspond to indirect illumination from the key light, bounced off a wall, floor, or other object. The fill light should never be brighter than the key light: a good range for the key-to-fill ratio is between 2 and 10.

virtual double vtkLightKit::GetKeyToFillRatio ( ) [virtual]

Set/Get the key-to-fill ratio. This ratio controls how bright the fill light is compared to the key light: larger values correspond to a dimmer fill light. The purpose of the fill light is to light parts of the object not lit by the key light, while still maintaining constrast. This type of lighting may correspond to indirect illumination from the key light, bounced off a wall, floor, or other object. The fill light should never be brighter than the key light: a good range for the key-to-fill ratio is between 2 and 10.

virtual void vtkLightKit::SetKeyToHeadRatio ( double ) [virtual]

Set/Get the key-to-headlight ratio. Similar to the key-to-fill ratio, this ratio controls how bright the headlight light is compared to the key light: larger values correspond to a dimmer headlight light. The headlight is special kind of fill light, lighting only the parts of the object that the camera can see. As such, a headlight tends to reduce the contrast of a scene. It can be used to fill in "shadows" of the object missed by the key and fill lights. The headlight should always be significantly dimmer than the key light: ratios of 2 to 15 are typical.

virtual double vtkLightKit::GetKeyToHeadRatio ( ) [virtual]

Set/Get the key-to-headlight ratio. Similar to the key-to-fill ratio, this ratio controls how bright the headlight light is compared to the key light: larger values correspond to a dimmer headlight light. The headlight is special kind of fill light, lighting only the parts of the object that the camera can see. As such, a headlight tends to reduce the contrast of a scene. It can be used to fill in "shadows" of the object missed by the key and fill lights. The headlight should always be significantly dimmer than the key light: ratios of 2 to 15 are typical.

virtual void vtkLightKit::SetKeyToBackRatio ( double ) [virtual]

Set/Get the key-to-back light ratio. This ratio controls how bright the back lights are compared to the key light: larger values correspond to dimmer back lights. The back lights fill in the remaining high-contrast regions behind the object. Values between 2 and 10 are good.

virtual double vtkLightKit::GetKeyToBackRatio ( ) [virtual]

Set/Get the key-to-back light ratio. This ratio controls how bright the back lights are compared to the key light: larger values correspond to dimmer back lights. The back lights fill in the remaining high-contrast regions behind the object. Values between 2 and 10 are good.

virtual void vtkLightKit::SetKeyLightWarmth ( double ) [virtual]

Set the warmth of each the lights. Warmth is a parameter that varies from 0 to 1, where 0 is "cold" (looks icy or lit by a very blue sky), 1 is "warm" (the red of a very red sunset, or the embers of a campfire), and 0.5 is a neutral white. The warmth scale is non-linear. Warmth values close to 0.5 are subtly "warmer" or "cooler," much like a warmer tungsten incandescent bulb, a cooler halogen, or daylight (cooler still). Moving further away from 0.5, colors become more quickly varying towards blues and reds. With regards to aesthetics, extremes of warmth should be used sparingly.

virtual double vtkLightKit::GetKeyLightWarmth ( ) [virtual]

Set the warmth of each the lights. Warmth is a parameter that varies from 0 to 1, where 0 is "cold" (looks icy or lit by a very blue sky), 1 is "warm" (the red of a very red sunset, or the embers of a campfire), and 0.5 is a neutral white. The warmth scale is non-linear. Warmth values close to 0.5 are subtly "warmer" or "cooler," much like a warmer tungsten incandescent bulb, a cooler halogen, or daylight (cooler still). Moving further away from 0.5, colors become more quickly varying towards blues and reds. With regards to aesthetics, extremes of warmth should be used sparingly.

virtual void vtkLightKit::SetFillLightWarmth ( double ) [virtual]

virtual double vtkLightKit::GetFillLightWarmth ( ) [virtual]

virtual void vtkLightKit::SetHeadLightWarmth ( double ) [virtual]

virtual double vtkLightKit::GetHeadLightWarmth ( ) [virtual]

virtual void vtkLightKit::SetBackLightWarmth ( double ) [virtual]

virtual double vtkLightKit::GetBackLightWarmth ( ) [virtual]

virtual double* vtkLightKit::GetKeyLightColor ( ) [virtual]