Class TAbstractLightNode

DescriptionHierarchyFieldsMethodsProperties

Unit

Declaration

type TAbstractLightNode = class(TAbstractChildNode)

Description

Base class for all VRML / X3D light nodes.

Note that even the old VRML 1.0 light nodes inherit from this. Although they interpret some bits differently ("ambientIntensity" < 0 has special meaning). But most of the fields behave identically, they only have different default values.

Hierarchy

Overview

Methods

Protected procedure BeforeTraverse(StateStack: TX3DGraphTraverseStateStack); override;
Protected procedure MiddleTraverse(StateStack: TX3DGraphTraverseStateStack); override;
Public procedure CreateNode; override;
Public function ProjectionMatrix: TMatrix4Single; virtual;
Public function ModelviewMatrix: TMatrix4Single; virtual;
Public function ModelviewRotationMatrix: TMatrix4Single; virtual;
Public function GetProjectorMatrix: TMatrix4Single;
Public function LocationLocal: TVector3Single; virtual;
Public function Location: TVector3Single;
Public function DirectionLocal: TVector3Single; virtual;
Public function Direction: TVector3Single;
Public procedure GetView(out Pos, Dir, Up: TVector3Single);
Public procedure Box3DDistances(const Box: TBox3D; out MinDistance, MaxDistance: Single); virtual; abstract;
Public function CreateLightInstance(State: TX3DGraphTraverseState): TLightInstance;
Public procedure UpdateLightInstanceState( var LightInstance: TLightInstance; State: TX3DGraphTraverseState);
Public procedure UpdateLightInstance( var LightInstance: TLightInstance); virtual;
Public function TransformationChange: TNodeTransformationChange; override;
Public function Scope: TLightScope; virtual;
Public function Position: TVector4Single; virtual; abstract;

Properties

Public property FdOn: TSFBool read FFdOn;
Public property FdIntensity: TSFFloat read FFdIntensity;
Public property FdColor: TSFColor read FFdColor;
Public property FdAmbientIntensity: TSFFloat read FFdAmbientIntensity;
Public property FdGlobal: TSFBool read FFdGlobal;
Public property FdShadowVolumes: TSFBool read FFdShadowVolumes;
Public property FdShadowVolumesMain: TSFBool read FFdShadowVolumesMain;
Public property FdShowProxyGeometry: TSFBool read FFdShowProxyGeometry;
Public property FdProjectionNear: TSFFloat read FFdProjectionNear;
Public property FdProjectionFar: TSFFloat read FFdProjectionFar;
Public property FdUp: TSFVec3f read FFdUp;
Public property FdDefaultShadowMap: TSFNode read FFdDefaultShadowMap;
Public property FdShadows: TSFBool read FFdShadows;
Public property FdEffects: TMFNode read FFdEffects;
Public property Transform: TMatrix4Single read FTransform;

Description

Methods

Protected procedure BeforeTraverse(StateStack: TX3DGraphTraverseStateStack); override;
 
Protected procedure MiddleTraverse(StateStack: TX3DGraphTraverseStateStack); override;
 
Public procedure CreateNode; override;
 
Public function ProjectionMatrix: TMatrix4Single; virtual;

Matrices for rendering shadow map from this light. Identity in this class, override for subclasses able to do shadow mapping.

Public function ModelviewMatrix: TMatrix4Single; virtual;
 
Public function ModelviewRotationMatrix: TMatrix4Single; virtual;
 
Public function GetProjectorMatrix: TMatrix4Single;
 
Public function LocationLocal: TVector3Single; virtual;

Light location, direction and up vectors. Useful for example when you think of lights as cameras (for shadow maps).

DirectionLocal must be exactly zero for PointLight (that doesn't have a direction).

Public function Location: TVector3Single;
 
Public function DirectionLocal: TVector3Single; virtual;
 
Public function Direction: TVector3Single;
 
Public procedure GetView(out Pos, Dir, Up: TVector3Single);
 
Public procedure Box3DDistances(const Box: TBox3D; out MinDistance, MaxDistance: Single); virtual; abstract;

Calculate distances between the given Box and this light source. This is intended to capture the depth distances where the box resides, useful for calculating e.g. depth ranges to capture in the shadow maps. Depending on light source type, various distance measures may be used, appropriate to light sources projection.

Always MinDistance <= MaxDistance. They may be negative when we measure along the light's direction.

Exceptions raised
EBox3DEmpty
When used with an empty box.
Public function CreateLightInstance(State: TX3DGraphTraverseState): TLightInstance;

Create TLightInstance record describing this light node under given State.

Public procedure UpdateLightInstanceState( var LightInstance: TLightInstance; State: TX3DGraphTraverseState);

Update TLightInstance record when lighting State changes. Assumes that LightInstance.Node = Self.

This will set LightInstance.Transform properties, and recalculate all LightInstance properties based on Transform.

Public procedure UpdateLightInstance( var LightInstance: TLightInstance); virtual;

Update TLightInstance record when lighting location/direction (and other properties precalculated on TLightInstance) change. Assumes that LightInstance.Node = Self.

Public function TransformationChange: TNodeTransformationChange; override;
 
Public function Scope: TLightScope; virtual;

Light scope. Default implementation returns lsGlobal or lsLocal, depending on "global" field value (this follows VRML/X3D >= 2.0 rules).

Public function Position: TVector4Single; virtual; abstract;

Position expressed in homogeneous coordinates. For positional lights, the last component is always 1. For directional lights, the last component is always 0.

Note that this expressed is in the local light node coordinate system.

Properties

Public property FdOn: TSFBool read FFdOn;
 
Public property FdIntensity: TSFFloat read FFdIntensity;
 
Public property FdColor: TSFColor read FFdColor;
 
Public property FdAmbientIntensity: TSFFloat read FFdAmbientIntensity;
 
Public property FdGlobal: TSFBool read FFdGlobal;
 
Public property FdShadowVolumes: TSFBool read FFdShadowVolumes;
 
Public property FdShadowVolumesMain: TSFBool read FFdShadowVolumesMain;
 
Public property FdShowProxyGeometry: TSFBool read FFdShowProxyGeometry;

showProxyGeometry field is an Avalon extension, see [http://instant-reality.com/documentation/nodetype/Light/].

Public property FdProjectionNear: TSFFloat read FFdProjectionNear;

projectionNear / projectionFar / up are Kambi extensions, see [http://castle-engine.sourceforge.net/x3d_extensions.php#section_ext_light_projective]

Public property FdProjectionFar: TSFFloat read FFdProjectionFar;
 
Public property FdUp: TSFVec3f read FFdUp;
 
Public property FdDefaultShadowMap: TSFNode read FFdDefaultShadowMap;
 
Public property FdShadows: TSFBool read FFdShadows;
 
Public property FdEffects: TMFNode read FFdEffects;
 
Public property Transform: TMatrix4Single read FTransform;

Transformation of this light node. Normal lights can be instanced many times within the scene, with various transformation, so this transformation property cannot be used.

However, in special cases, you know that light node occurs only once within the scene (see [http://castle-engine.sourceforge.net/x3d_extensions.php#section_ext_shadow_maps]). Then it's useful.

It is gathered during traversing. Last BeforeTraverse call for this node sets Transform properties. By default, it represents identity transformation.


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