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SoShadowGroup.3coin2

NAME

SoShadowGroup -

The SoShadowGroup node is a group node used for shadow rendering.

Children of this node can recieve shadows, and cast shadows on other children. Use the SoShadowStyle node to control shadow casters and shadow receivers.

SYNOPSIS

#include <FXViz/nodes/SoSeparator.h>

Inherits SoSeparator.

Public Types

enum VisibilityFlag { ABSOLUTE_RADIUS, LONGEST_BBOX_EDGE_FACTOR, PROJECTED_BBOX_DEPTH_FACTOR }

Public Member Functions

SoShadowGroup (void)

virtual void GLRenderBelowPath (SoGLRenderAction *action)

virtual void GLRenderInPath (SoGLRenderAction *action)

virtual void notify (SoNotList *nl)

Static Public Member Functions

static void initClass (void)

static void init (void)

Public Attributes

SoSFBool isActive

SoSFFloat intensity

SoSFFloat precision

SoSFFloat quality

SoSFFloat smoothBorder

SoSFBool shadowCachingEnabled

SoSFFloat visibilityNearRadius

SoSFFloat visibilityRadius

SoSFEnum visibilityFlag

SoSFFloat epsilon

SoSFFloat threshold

Protected Member Functions

virtual ~SoShadowGroup ()

Detailed Description

The SoShadowGroup node is a group node used for shadow rendering.

Children of this node can recieve shadows, and cast shadows on other children. Use the SoShadowStyle node to control shadow casters and shadow receivers.

Please note that all shadow casters will be rendered twice. Once to create the shadow map, and once for normal rendering. If you're having performance issues, you should consider reducing the number of shadow casters.

The algorithm used to render the shadows is Variance Shadow Maps (http://www.punkuser.net/vsm/). As an extra bonus, all geometry rendered with shadows can also be rendered with per fragment phong lighting.

This node will search its subgraph and calculate shadows for all SoSpotLight nodes. The node will use one texture unit for each spot light, so for this node to work 100%, you need to have num-spotlights free texture units while rendering the subgraph.

Currently, we only support scenes with maximum two texture units active while doing shadow rendering (unit 0 and unit 1). This is due to the fact that we emulate the OpenGL shading model in a shader program, and we're still working on creating a solution that updates the shader program during the scene graph traversal. Right now a shader program is created when entering the SoShadowGroup node, and this is used for the entire subgraph.

FILE FORMAT/DEFAULTS:

     SoShadowGroup {
       isActive TRUE
       intensity 0.5
       precision 0.5
       quality 0.5
       shadowCachingEnabled TRUE
       visibilityRadius -1.0
       visibilityFlag LONGEST_BBOX_EDGE_FACTOR
 
       epsilon 0.00001
       threshold 0.1
       smoothBorder 0.0
 
     }
 
 

Example scene graph:

   # to get some lighting when headlight is turned off in the viewer
   DirectionalLight { direction 0 0 -1 intensity 0.2 }
 
   ShadowGroup {
     quality 1 # to get per pixel lighting
 
     ShadowStyle { style NO_SHADOWING }
 
     SpotLight {
       location -8 -8 8.0
       direction 1 1 -1
       cutOffAngle 0.35
       dropOffRate 0.7
     }
 
     ShadowStyle { style CASTS_SHADOW_AND_SHADOWED }
 
     Separator {
       Complexity { value 1.0 }
       Material { diffuseColor 1 1 0 specularColor 1 1 1 shininess 0.9 }
       Shuttle { translation0 -3 1 0 translation1 3 -5 0 speed 0.25 on TRUE }
       Translation { translation -5 0 2 }
       Sphere { radius 2.0 }
     }
 
     Separator {
       Material { diffuseColor 1 0 0 specularColor 1 1 1 shininess 0.9 }
       Shuttle { translation0 0 -5 0 translation1 0 5 0 speed 0.15 on TRUE }
       Translation { translation 0 0 -3 }
       Cube { depth 1.8 }
     }
     Separator {
       Material { diffuseColor 0 1 0 specularColor 1 1 1 shininess 0.9 }
       Shuttle { translation0 -5 0 0 translation1 5 0 0 speed 0.3 on TRUE }
       Translation { translation 0 0 -3 }
       Cube { }
     }
 
     ShadowStyle { style SHADOWED }
     Coordinate3 { point [ -10 -10 -3, 10 -10 -3, 10 10 -3, -10 10 -3 ] }
     Material { specularColor 1 1 1 shininess 0.9 }
 
     Complexity { textureQuality 0.1 }
     Texture2 { image 2 2 3 0xffffff 0x225588 0x225588 0xffffff }
     Texture2Transform { scaleFactor 4 4 }
     FaceSet { numVertices 4 }
   }
 
 

Since:

Coin 2.5

Constructor & Destructor Documentation

SoShadowGroup::SoShadowGroup (void)Default constructor.

References epsilon, intensity, isActive, precision, shadowCachingEnabled, smoothBorder, threshold, visibilityFlag, visibilityNearRadius, and visibilityRadius.

SoShadowGroup::~SoShadowGroup () [protected, virtual]Destructor.

Member Function Documentation

void SoShadowGroup::initClass (void) [static]Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system.

Reimplemented from SoSeparator.

void SoShadowGroup::GLRenderBelowPath (SoGLRenderAction * action) [virtual]SGI Open Inventor v2.1 obsoleted support for SoGLRenderAction::addMethod(). Instead, GLRender() might be called directly, and to optimize traversal, the SoSeparator node calls GLRenderBelowPath whenever the path code is BELOW_PATH or NO_PATH (path code is guaranteed not to change). To be compatible with SGI's Inventor (and thereby also TGS') we have chosen to follow their implementation in this respect.

SoSeparator::GLRenderBelowPath() do not traverse its children using SoChildList::traverse(), but calls GLRenderBelowPath() directly for all its children.

Reimplemented from SoSeparator.

void SoShadowGroup::GLRenderInPath (SoGLRenderAction * action) [virtual]Implements the SoAction::IN_PATH traversal method for the rendering action.

Reimplemented from SoSeparator.

void SoShadowGroup::notify (SoNotList * l) [virtual]Notifies all auditors for this instance when changes are made.

Reimplemented from SoSeparator.

References SoNotRec::getBase(), SoNode::getClassTypeId(), SoNotList::getFirstRecAtNode(), SoNotList::getLastRec(), SoBase::isOfType(), and SoSeparator::notify().

Member Data Documentation

SoSFBool SoShadowGroup::isActiveUse this field to turn shadow rendering for the subgraph on/off. Default value is TRUE.

Referenced by SoShadowGroup().

SoSFFloat SoShadowGroup::intensityNot used yet. Provided for TGS Inventor compatibility.

Referenced by SoShadowGroup().

SoSFFloat SoShadowGroup::precisionUse to calculate the size of the shadow map. A precision of 1.0 means the maximum shadow buffer size will be used (typically 2048x2048 on current graphics cards). Default value is 0.5.

Referenced by SoShadowGroup().

SoSFFloat SoShadowGroup::qualityCan be used to tune the shader program complexity. A higher value will mean that more calculations are done per-fragment instead of per-vertex. Default value is 0.5.

SoSFInt32 SoShadowGroup::smoothBorderSoShadowGroup::VisibilityFlag SoShadowGroup::ABSOLUTE_RADIUS

The absolute values of visibilityNearRadius and visibilityRadius will be used.

SoShadowGroup::VisibilityFlag SoShadowGroup::LONGEST_BBOX_EDGE_FACTOR

The longest bbox edge will be used to determine near and far clipping planes.

SoShadowGroup::VisibilityFlag SoShadowGroup::PROJECTED_BBOX_DEPTH_FACTOR

The bbox depth (projected to face the camera) will be used to calculate the clipping planes.

We have some problems with this feature so it's not supported at the moment.

Used to add shadow border smoothing. This is currently done as a post processing step on the shadow map. The algorithm used is Gauss Smoothing, but in the future we'll probably change this, and use a summed area sampling merhod instead. The value should be a number between 0 (no smoothing), and 1 (max smoothing).

If you want to enable smoothing, choosing a low value (~0.1) works best in the current implementation.

Default value is 0.0.

Referenced by SoShadowGroup().

SoSFBool SoShadowGroup::shadowCachingEnabledNot used yet. Provided for TGS Inventor compatibility.

Referenced by SoShadowGroup().

SoSFFloat SoShadowGroup::visibilityNearRadiusCan be used to manually set the near clipping plane of the shadow maps. If a negative value is provided, the group will calculate a near plane based on the bounding box of the children. Default value is -1.0.

See also:

visibilityFlag

Referenced by SoShadowGroup().

SoSFFloat SoShadowGroup::visibilityRadiusCan be used to manually set the far clipping plane of the shadow maps. If a negative value is provided, the group will calculate a near plane based on the bounding box of the children. Default value is -1.0.

See also:

visibilityFlag

Referenced by SoShadowGroup().

SoSFEnum SoShadowGroup::visibilityFlagDetermines how visibilityRadius and visibilitNearRadius is used to calculate near and far clipping planes for the shadow volume.

Referenced by SoShadowGroup().

SoSFFloat SoShadowGroup::epsilonEpsilon is used to offset the shadow map depth from the model depth. Should be set to as low a number as possible without causing flickering in the shadows or on non-shadowed objects. Default value is 0.00001.

Referenced by SoShadowGroup().

SoSFFloat SoShadowGroup::thresholdCan be used to avoid light bleeding in merged shadows cast from different objects.

A threshold to completely eliminate all light bleeding can be computed from the ratio of overlapping occluder distances from the light's perspective. See http://forum.beyond3d.com/showthread.php?t=38165 for a discussion about this problem.

Referenced by SoShadowGroup().

Author

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