Open Inventor Release 2024.2.1
 
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SoLightModel Class Reference

Node that defines the lighting model to use when rendering. More...

#include <Inventor/nodes/SoLightModel.h>

+ Inheritance diagram for SoLightModel:

Public Types

enum  Model {
  BASE_COLOR = SoLightModelElement::BASE_COLOR ,
  PHONG = SoLightModelElement::PHONG ,
  PER_VERTEX_PHONG = SoLightModelElement::PER_VERTEX_PHONG ,
  PER_PIXEL_PHONG = SoLightModelElement::PER_PIXEL_PHONG ,
  PHYSICALLY_BASED = SoLightModelElement::PHYSICALLY_BASED
}
 Lighting model. More...
 

Public Member Functions

virtual SoType getTypeId () const
 Returns the type identifier for this specific instance.
 
 SoLightModel ()
 Creates a light model node with default settings.
 
virtual void setOverride (const SbBool state)
 Set the state of the override field.
 
virtual SbBool isOverride () const
 Returns the state of the override field.
 
- Public Member Functions inherited from SoNode
virtual SoNodecopy (SbBool copyConnections=FALSE) const
 Creates and returns an exact copy of the node.
 
virtual SbBool affectsState () const
 Returns TRUE if a node has an effect on the state during traversal.
 
virtual void touch ()
 Marks an instance as modified, simulating a change to it.
 
- Public Member Functions inherited from SoFieldContainer
void setToDefaults ()
 Sets all fields in this object to their default values.
 
SbBool hasDefaultValues () const
 Returns TRUE if all of the object's fields have their default values.
 
SbBool fieldsAreEqual (const SoFieldContainer *fc) const
 Returns TRUE if this object's fields are exactly equal to fc's fields.
 
void copyFieldValues (const SoFieldContainer *fc, SbBool copyConnections=FALSE)
 Copies the contents of fc's fields into this object's fields.
 
SoNONUNICODE SbBool set (const char *fieldDataString)
 Sets one or more fields in this object to the values specified in the given string, which should be a string in the Open Inventor file format.
 
SbBool set (const SbString &fieldDataString)
 Sets one or more fields in this object to the values specified in the given string, which should be a string in the Open Inventor file format.
 
void get (SbString &fieldDataString)
 Returns the values of the fields of this object in the Open Inventor ASCII file format in the given string.
 
virtual int getFields (SoFieldList &list) const
 Appends references to all of this object's fields to resultList, and returns the number of fields appended.
 
virtual int getAllFields (SoFieldList &list) const
 Returns a list of fields, including the eventIn's and eventOut's.
 
virtual SoFieldgetField (const SbName &fieldName) const
 Returns a the field of this object whose name is fieldName.
 
virtual SoFieldgetEventIn (const SbName &fieldName) const
 Returns a the eventIn with the given name.
 
virtual SoFieldgetEventOut (const SbName &fieldName) const
 Returns the eventOut with the given name.
 
SbBool getFieldName (const SoField *field, SbName &fieldName) const
 Returns the name of the given field in the fieldName argument.
 
SbBool enableNotify (SbBool flag)
 Notification at this Field Container is enabled (if flag == TRUE) or disabled (if flag == FALSE).
 
SbBool isNotifyEnabled () const
 Notification is the process of telling interested objects that this object has changed.
 
virtual void setUserData (void *data)
 Sets application data.
 
void * getUserData (void) const
 Gets user application data.
 
- Public Member Functions inherited from SoBase
virtual SbName getName () const
 Returns the name of an instance.
 
virtual void setName (const SbName &name)
 Sets the name of an instance.
 
void setSynchronizable (const bool b)
 Sets this to be a ScaleViz synchronizable object.
 
bool isSynchronizable () const
 Gets the ScaleViz synchronizable state of this object.
 
- Public Member Functions inherited from SoRefCounter
void ref () const
 Adds a reference to an instance.
 
void unref () const
 Removes a reference from an instance.
 
void unrefNoDelete () const
 unrefNoDelete() should be called when it is desired to decrement the reference count, but not delete the instance if this brings the reference count to zero.
 
int getRefCount () const
 Returns current reference count.
 
void lock () const
 lock this instance.
 
void unlock () const
 unlock this instance.
 
- Public Member Functions inherited from SoTypedObject
SbBool isOfType (const SoType &type) const
 Returns TRUE if this object is of the type specified in type or is derived from that type.
 
template<typename TypedObjectClass >
SbBool isOfType () const
 Returns TRUE if this object is of the type of class TypedObjectClass or is derived from that class.
 

Static Public Member Functions

static SoType getClassTypeId ()
 Returns the type identifier for this class.
 
- Static Public Member Functions inherited from SoNode
static SoType getClassTypeId ()
 Returns the type identifier for this class.
 
static SoNodegetByName (const SbName &name)
 A node's name can be set using SoBase::setName().
 
static int getByName (const SbName &name, SoNodeList &list)
 A node's name can be set using SoBase::setName().
 
- Static Public Member Functions inherited from SoFieldContainer
static SoType getClassTypeId ()
 Returns the type of this class.
 
- Static Public Member Functions inherited from SoBase
static SoType getClassTypeId ()
 Returns type identifier for this class.
 
- Static Public Member Functions inherited from SoTypedObject
static SoType getClassTypeId ()
 Returns the type identifier for this class.
 

Public Attributes

SoSFEnum model
 Lighting model to use Use enum Model.
 

Detailed Description

Node that defines the lighting model to use when rendering.

This node defines the lighting model to use when rendering subsequent shapes. The lighting model is specified in the model field, which is PER_VERTEX_PHONG by default.

SoLightModel supports several types of light model. The following images provide examples of rendering the same scene using a different light model.

BASE_COLOR PER_PIXEL_PHONG PHYSICALLY_BASED

When the light model is not BASE_COLOR, there must be light nodes (e.g. SoDirectionalLight) in the scene graph for objects to be easily visible. When using the Open Inventor viewer classes (e.g. SoWinExaminerViewer), the viewer will create a "headlight" (directional light attached to the camera) if no other light nodes exist when setSceneGraph() is called. When using the Open Inventor viewer components (e.g. SceneExaminer), a "headlight" is automatically added to the scene graph.

You can use a SoEnvironment node to specify additional lighting options:

  • The ambient light component of the Phong reflection model.
  • Light attenuation for SoPointLight and SoSpotLight nodes.
  • Ambient occlusion.

Definition of base color

All the light models supported by Open Inventor use the concept of base color composed of 3 channels red green blue (rgb). It corresponds to the color of an object before being altered by light effects. Unfortunatly the term base color is not always used in the API and documentation, sometimes it is referred to as diffuse color, rgb color*, a rgb or just color.

The following fields define the same concept of base color of an object:

The following C++ code samples are equivalent and define a single red opaque base color:

// using SoMaterial
mySoMaterial->diffuseColor = SbColor(1,0,0);
mySoMaterial->transparency = 0 ;
// using SoPhysicalMaterial
mySoPhysicalMaterial->baseColor = SbColorRGBA(1,0,0,1);
// using SoBaseColor
mySoBaseColor->rgb = SbColor(1,0,0);
// using SoPackedColor
mySoPackedColor->orderedRGBA = SbColorRGBA(1,0,0,1).getPackedValue();
// using SoColorMap
mySoColorMap->colorMap.setValues(0, 4, new float[4]{ 1, 0, 0, 1 });
// using SoBufferedShape
mySoBufferedShape->colorBuffer = new SoCpuBufferObject(new float[4]{ 1, 0, 0, 1 }, 4 * sizeof(float));
// using SoVertexProperty
mySoVertexProperty->orderedRGBA = SbColorRGBA(1,0,0,1).getPackedValue();
Color vector class.
Definition SbColor.h:82
ColorRGBA vector class.
Definition SbColorRGBA.h:61
uint32_t getPackedValue() const
Returns an RGBA packed color value, derived from the color vector.
<a href="IconLegend.html"><img src="extTGS.gif" alt="VSG extension" border="0"></a> CPU buffer objec...

Changing the value of any of those fields overrides the base color of an object. This means that if you set 2 different fields to specify a color, the current definition of a color during the scene graph traversal overrides the previous one. For instance, the following code sample specifies an opaque red color that overrides the semi opaque green.

mySoPhysicalMaterial->baseColor = SbColorRGBA(0,1,0,0.5f); // semi opaque green color
mySoMaterial->diffuseColor = SbColor(1,0,0); // red color
mySoMaterial->transparency = 0 ;
myRoot->addChild(mySoPhysicalMaterial);
myRoot->addChild(mySoMaterial); // this red material overrides the green color

Light model and property nodes

According to the light model selected, the following notes explain what is taken into account in the scene graph, and what is ignored:

Using model BASE_COLOR

  • Objects are drawn using the base color only. There is no lighting.
  • If a node related to the material is visited after SoBaseColor during the traversal, the rgb defined by the SoBaseColor may change.
  • The base color is specified as described above.
  • The SoMaterial fields are ignored except diffuseColor and transparency.
  • The SoPhysicalMaterial fields are ignored except baseColor.
  • The SoLight instances are ignored.
  • The SoEnvironment instances are ignored.

Using PER_VERTEX_PHONG or PER_PIXEL_PHONG

  • The lighting takes into account all fields of SoMaterial.
  • If a node related to the material is visited after the SoMaterial during the traversal, the diffuseColor and transparency defined by the SoMaterial may change
  • The base color is specified as described above.
  • The SoPhysicalMaterial fields are ignored except baseColor.
  • The SoLight instances are used.
  • The SoEnvironment instances are used.

Using PHYSICALLY_BASED

Two side lighting

By default, lighting is only computed for the "front" faces of the geometry, leaving the back face of the geometry dark. If the normal vector is specified, it determines the front face. If normals are computed by Open Inventor, the vertex ordering (see SoShapeHints) determines the front face. To enable "two sided" lighting (lighting both front and back faces) see SoShapeHints.

Light model and VolumeViz

The SoLightModel node controls lighting for most VolumeViz shapes, but not for SoVolumeRender. The lighting for volume rendering is controlled by the SoVolumeRenderingQuality node.

Two sided lighting is automatically enabled for "slice" shapes, such as SoOrthoSlice.

FILE FORMAT/DEFAULT

    LightModel {
    model PER_VERTEX_PHONG
    }

ACTION BEHAVIOR

SEE ALSO

SoBaseColor, SoEnvironment, SoLight, SoDirectionalLight, SoPointLight, SoSpotLight, SoPhysicalMaterial, SoMaterial

Definition at line 245 of file SoLightModel.h.

Member Enumeration Documentation

◆ Model

Lighting model.

Enumerator
BASE_COLOR 

Use only the base color of an object.

Effectively lighting is turned off and light nodes are not considered. This mode is adapted to render annotation, for data visualization, for 2D scenes, and other special cases.

PHONG 

Use Phong lighting model.

PER_VERTEX_PHONG 

Use the Vertex-based Phong lighting model (default).

Lighting is computed at each vertex of the shape and the color of each pixel (fragment) is determined by interpolating between these values. This model produces less realistic results than pixel-based lighting, especially for Point and Spot lights.

PER_PIXEL_PHONG 

Use the Pixel-based Phong lighting model.

A lighting computation is done for each pixel (fragment) affected by the shape.

PHYSICALLY_BASED 

Use the physically based lighting model.

Definition at line 251 of file SoLightModel.h.

Constructor & Destructor Documentation

◆ SoLightModel()

SoLightModel::SoLightModel ( )

Creates a light model node with default settings.

Member Function Documentation

◆ getClassTypeId()

static SoType SoLightModel::getClassTypeId ( )
static

Returns the type identifier for this class.


◆ getTypeId()

virtual SoType SoLightModel::getTypeId ( ) const
virtual

Returns the type identifier for this specific instance.

Reimplemented from SoNode.

◆ isOverride()

virtual SbBool SoLightModel::isOverride ( ) const
inlinevirtual

Returns the state of the override field.

Reimplemented from SoNode.

Definition at line 303 of file SoLightModel.h.

◆ setOverride()

virtual void SoLightModel::setOverride ( const SbBool  state)
inlinevirtual

Set the state of the override field.

see SoNode::setOverride doc.

Reimplemented from SoNode.

Definition at line 297 of file SoLightModel.h.

Member Data Documentation

◆ model

SoSFEnum SoLightModel::model

Lighting model to use Use enum Model.

Default is PER_VERTEX_PHONG.

Definition at line 286 of file SoLightModel.h.


The documentation for this class was generated from the following file: