#include <vtkLightKit.h>
Inheritance diagram for vtkLightKit:
Public Methods | |
virtual const char * | GetClassName () |
virtual int | IsA (const char *type) |
void | PrintSelf (ostream &os, vtkIndent indent) |
virtual void | SetKeyLightIntensity (float) |
virtual float | GetKeyLightIntensity () |
virtual void | SetKeyToFillRatio (float) |
virtual float | GetKeyToFillRatio () |
virtual void | SetKeyToHeadRatio (float) |
virtual float | GetKeyToHeadRatio () |
virtual void | SetKeyLightWarmth (float) |
virtual float | GetKeyLightWarmth () |
virtual void | SetFillLightWarmth (float) |
virtual float | GetFillLightWarmth () |
virtual void | SetHeadlightWarmth (float) |
virtual float | GetHeadlightWarmth () |
virtual float * | GetKeyLightColor () |
virtual void | GetKeyLightColor (float data[3]) |
virtual float * | GetFillLightColor () |
virtual void | GetFillLightColor (float data[3]) |
virtual float * | GetHeadlightColor () |
virtual void | GetHeadlightColor (float data[3]) |
virtual void | MaintainLuminanceOn () |
virtual void | MaintainLuminanceOff () |
virtual int | GetMaintainLuminance () |
virtual void | SetMaintainLuminance (int) |
void | SetKeyLightAngle (float elevation, float azimuth) |
void | SetKeyLightAngle (float angle[2]) |
void | SetKeyLightElevation (float x) |
void | SetKeyLightAzimuth (float x) |
virtual float * | GetKeyLightAngle () |
virtual void | GetKeyLightAngle (float data[2]) |
float | GetKeyLightElevation () |
float | GetKeyLightAzimuth () |
void | SetFillLightAngle (float elevation, float azimuth) |
void | SetFillLightAngle (float angle[2]) |
void | SetFillLightElevation (float x) |
void | SetFillLightAzimuth (float x) |
virtual float * | GetFillLightAngle () |
virtual void | GetFillLightAngle (float data[2]) |
float | GetFillLightElevation () |
float | GetFillLightAzimuth () |
void | AddLightsToRenderer (vtkRenderer *renderer) |
void | RemoveLightsFromRenderer (vtkRenderer *renderer) |
void | DeepCopy (vtkLightKit *kit) |
void | Modified () |
void | Update () |
Static Public Methods | |
vtkLightKit * | New () |
int | IsTypeOf (const char *type) |
vtkLightKit * | SafeDownCast (vtkObject *o) |
Protected Methods | |
vtkLightKit () | |
~vtkLightKit () | |
void | WarmthToRGBI (float w, float rgb[3], float &i) |
void | WarmthToRGB (float w, float rgb[3]) |
void | InitializeWarmthFunctions () |
float | WarmthToIntensity (float w) |
vtkLightKit (const vtkLightKit &) | |
void | operator= (const vtkLightKit &) |
Protected Attributes | |
float | KeyLightIntensity |
float | KeyToFillRatio |
float | KeyToHeadRatio |
vtkLight * | KeyLight |
float | KeyLightWarmth |
float | KeyLightAngle [2] |
float | KeyLightColor [3] |
vtkLight * | FillLight |
float | FillLightWarmth |
float | FillLightAngle [2] |
float | FillLightColor [3] |
vtkLight * | Headlight |
float | HeadlightWarmth |
float | HeadlightColor [3] |
int | MaintainLuminance |
vtkPiecewiseFunction * | WarmthFunction [4] |
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 two lights in the kit, the fill light and headlight, 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. To enforce the relationship between the three lights, the intensity of the fill 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.
|
Add lights to, or remove lights from, a renderer. Lights may be added to more than one renderer, if desired. |
|
Return the class name as a string. This method is defined in all subclasses of vtkObject with the vtkTypeMacro found in vtkSetGet.h. Reimplemented from vtkObject. |
|
Returns the floating-point RGB values of each of the light's color. |
|
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 vtkTypeMacro found in vtkSetGet.h. Reimplemented from vtkObject. |
|
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 vtkTypeMacro found in vtkSetGet.h. Reimplemented from vtkObject. |
|
If MaintainLuminance is set, the LightKit will attempt to maintain the apparent intensity of lights based on their perceptual brightnesses. By default, MaintainLuminance is off. |
|
Update the modification time for this object. Many filters rely on the modification time to determine if they need to recompute their data. The modification time is a unique monotonically increasing unsigned long integer. Reimplemented from vtkObject. |
|
Create an object with Debug turned off, modified time initialized to zero, and reference counting on. Reimplemented from vtkObject. |
|
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. |
|
Will cast the supplied object to vtkObject* is this is a safe operation (i.e., a safe downcast); otherwise NULL is returned. This method is defined in all subclasses of vtkObject with the vtkTypeMacro found in vtkSetGet.h. Reimplemented from vtkObject. |
|
Get/Set the position of the key light and fill light, using angular methods. Elevation corresponds to latitude, azimuth to longitude. It is recommended that the key light always be on the viewer's side of the object and above the object, while the fill light generally lights the part of the object not lit by the fill light. The headlight, which is always located at the viewer, can then be used to reduce the contrast in the image. |
|
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. |
|
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. |
|
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 3 and 10. |
|
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 3 to 15 are typical. |