Light
Introduction
vtkLight is a virtual light for 3D rendering. It provides methods to locate and point the light, turn it on and off, and set its brightness and color. In addition to the basic infinite distance point light source attributes, you also can specify the light attenuation values and cone angle. These attributes are only used if the light is a positional light. The default is a directional light (e.g. infinite point light source).
Lights have a type that describes how the light should move with respect to the camera. A Headlight is always located at the current camera position and shines on the camera’s focal point. A CameraLight also moves with the camera, but may not be coincident to it. CameraLights are defined in a normalized coordinate space where the camera is located at (0, 0, 1), the camera is looking at (0, 0, 0), and up is (0, 1, 0). Finally, a SceneLight is part of the scene itself and does not move with the camera. (Renderers are responsible for moving the light based on its type.)
Lights have a transformation matrix that describes the space in which they are positioned. A light’s world space position and focal point are defined by their local position and focal point, transformed by their transformation matrix (if it exists).
Methods
extend
Method use to decorate a given object (publicAPI+model) with vtkLight characteristics.
| Argument | Type | Required | Description |
|---|---|---|---|
publicAPI | Yes | object on which methods will be bounds (public) | |
model | Yes | object on which data structure will be bounds (protected) | |
initialValues | ILightInitialValues | No | (default: {}) |
getAttenuationValues
getAttenuationValuesByReference
getColor
Get the color of the light.
getColorByReference
Get the color of the light.
getConeAngle
Get the lighting cone angle of a positional light in degrees. This is the angle between the axis of the cone and a ray along the edge of the cone. A value of 90 (or more) indicates that you want no spot lighting effects just a positional light.
getConeFalloff
Get the lighting falloff angle of a positional light in degrees. This is the angle that sets how much the cone will be extended to smooth the border. A value of 0 indicates that the spot light will have a completely sharp edge (this does not mean completely sharp lighting, just that the border will be sharp).
getDirection
Set the position and focal point of a light based on elevation and azimuth. The light is moved so it is shining from the given angle. Angles are given in degrees. If the light is a positional light, it is made directional instead.
getExponent
Get the exponent of the cosine used in positional lighting.
getFocalPoint
Get the focal point.
getFocalPointByReference
Get the focal point.
getIntensity
Get the brightness of the light
getLightType
Get the type of the light.
getPosition
Get the position of the light.
getPositionByReference
Get the position of the light.
getPositional
Get if positional lighting is on or off.
getTransformedFocalPoint
Get the focal point of the light, modified by the transformation matrix (if it exists).
getTransformedPosition
Get the position of the light, modified by the transformation matrix (if it exists).
lightTypeIsCameraLight
Check if the type of the light is CameraLight.
lightTypeIsHeadLight
Check if the type of the light is HeadLight.
lightTypeIsSceneLight
Check if the type of the light is SceneLight.
newInstance
Method use to create a new instance of vtkLight with the focal point at the origin and its position set to [0, 0, 1]. The light is a SceneLight, its color is white, intensity=1, the light is turned on, positional lighting is off, coneAngle=30, coneFalloff=5, AttenuationValues=[1, 0, 0], exponent=1 and the transformMatrix is null.
| Argument | Type | Required | Description |
|---|---|---|---|
initialValues | ILightInitialValues | No | for pre-setting some of its content |
setAttenuationValues
Set the quadratic attenuation constants.
| Argument | Type | Required | Description |
|---|---|---|---|
a | Number | Yes | |
b | Number | Yes | |
c | Number | Yes |
setAttenuationValuesFrom
Set the quadratic attenuation constants from an array.
| Argument | Type | Required | Description |
|---|---|---|---|
attenuationValues | Array[Number] | Yes | The quadratic attenuation. |
setColor
Set the color of the object. Has the side effect of setting the ambient diffuse and specular colors as well. This is basically a quick overall color setting method.
| Argument | Type | Required | Description |
|---|---|---|---|
color | RGBColor | Yes | Defines the RGB color array.. |
setColor
Set the color of the object. Has the side effect of setting the ambient diffuse and specular colors as well. This is basically a quick overall color setting method.
| Argument | Type | Required | Description |
|---|---|---|---|
r | Number | Yes | Defines the red component (between 0 and 1). |
g | Number | Yes | Defines the green component (between 0 and 1). |
b | Number | Yes | Defines the blue component (between 0 and 1). |
setColorFrom
Set the color of the object. Has the side effect of setting the ambient diffuse and specular colors as well. This is basically a quick overall color setting method.
| Argument | Type | Required | Description |
|---|---|---|---|
color | RGBColor | Yes | Defines the RGB color array.. |
setColorFrom
Set the color of the object. Has the side effect of setting the ambient diffuse and specular colors as well. This is basically a quick overall color setting method.
| Argument | Type | Required | Description |
|---|---|---|---|
r | Number | Yes | Defines the red component (between 0 and 1). |
g | Number | Yes | Defines the green component (between 0 and 1). |
b | Number | Yes | Defines the blue component (between 0 and 1). |
setConeAngle
Set the lighting cone angle of a positional light in degrees. This is the angle between the axis of the cone and a ray along the edge of the cone. A value of 90 (or more) indicates that you want no spot lighting effects just a positional light.
| Argument | Type | Required | Description |
|---|---|---|---|
coneAngle | Number | Yes | The cone angle. |
setConeFalloff
Set the lighting falloff angle of a positional light in degrees. This is the angle that sets how much the cone will be extended to smooth the border. A value of 0 indicates that the spot light will have a completely sharp edge (this does not mean completely sharp lighting, just that the border will be sharp).
| Argument | Type | Required | Description |
|---|---|---|---|
coneFalloff | Number | Yes | The cone falloff angle. |
setDirection
Set the direction vector of the light from X, Y, and Z values
| Argument | Type | Required | Description |
|---|---|---|---|
direction | Vector3 | Yes |
setDirection
Set the direction vector of the light from X, Y, and Z values
| Argument | Type | Required | Description |
|---|---|---|---|
x | Number | Yes | The x coordinate. |
y | Number | Yes | The y coordinate. |
z | Number | Yes | The z coordinate. |
setDirectionAngle
Set the position and focal point of a light based on elevation and azimuth. The light is moved so it is shining from the given angle. Angles are given in degrees. If the light is a positional light, it is made directional instead.
| Argument | Type | Required | Description |
|---|---|---|---|
elevation | Number | Yes | |
azimuth | Number | Yes |
setExponent
Set the exponent of the cosine used in positional lighting.
| Argument | Type | Required | Description |
|---|---|---|---|
exponent | Number | Yes | The exponent of the cosine. |
setFocalPoint
Set the focal point.
| Argument | Type | Required | Description |
|---|---|---|---|
x | Number | Yes | The x coordinate. |
y | Number | Yes | The y coordinate. |
z | Number | Yes | The z coordinate. |
setFocalPointFrom
Set the focal point from an array
| Argument | Type | Required | Description |
|---|---|---|---|
focalPoint | Vector3 | Yes | The focal point array. |
setIntensity
Set the brightness of the light (from one to zero).
| Argument | Type | Required | Description |
|---|---|---|---|
intensity | Number | Yes |
setLightType
Set the type of the light to lightType
| Argument | Type | Required | Description |
|---|---|---|---|
lightType | LIGHT_TYPES | Yes | The light type. |
setLightTypeToCameraLight
Set the type of the light is CameraLight.
setLightTypeToHeadLight
Set the the type of the light is HeadLight.
setLightTypeToSceneLight
Set the the type of the light is SceneLight.
setPosition
Set the position of the light.
| Argument | Type | Required | Description |
|---|---|---|---|
x | Number | Yes | The x coordinate. |
y | Number | Yes | The y coordinate. |
z | Number | Yes | The z coordinate. |
setPositionFrom
Set the position of the light.
| Argument | Type | Required | Description |
|---|---|---|---|
position | Vector3 | Yes | The position coordinate of the light. |
setPositional
Turn positional lighting on or off.
| Argument | Type | Required | Description |
|---|---|---|---|
positional | Boolean | Yes | The positional value. |
setShadowAttenuation
Set the shadow intensity By default a light will be completely blocked when in shadow by setting this value to less than 1.0 you can control how much light is attenuated when in shadow.
| Argument | Type | Required | Description |
|---|---|---|---|
shadowAttenuation | Number | Yes | The shadow attenuation value. |
setSwitch
Turn the light on or off.
| Argument | Type | Required | Description |
|---|---|---|---|
switchValue | Boolean | Yes | The switch value. |
setTransformMatrix
Set the light's transformation matrix.
| Argument | Type | Required | Description |
|---|---|---|---|
transformMatrix | mat4 | Yes | The transform matrix. |