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/SoShadowGroup.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)
void enableSubgraphSearchOnNotify (const SbBool onoff)
Static Public Member Functions
static void initClass (void)
static void init (void)
static SbBool isSupported (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:
#Inventor V2.1 ascii
# 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.
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.
SbBool SoShadowGroup::isSupported (void) [static] Reports whether or not
the shadow nodes can be used successfully on the current system.
The result will depend on the specific qualities of the graphics card
and OpenGL driver on the system.
An important note about this function:
The API design of this function has a serious shortcoming, as features
of OpenGL should be tested within an OpenGL context, and this function
does not provide any means of specifying the context. It is implemented
in this manner to match the function signature in TGS Inventor, for
compatibility reasons.
(A temporary offscreen OpenGL context is set up for the feature tests.
This should usually be sufficient to decide whether or not the graphics
driver / card supports the features needed for rendering shadows.)
Since:
Coin 3.1
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.
void SoShadowGroup::enableSubgraphSearchOnNotify (const SbBool onoff) By
default, the SoShadowGroup node will search its subgraph for new spot
lights whenever a group node under it is touched. However, this might
lead to bad performance in some cases so it’s possible to disable this
feature using this method. If you do disable this feature, make sure
you enable it again before inserting a new spot light, or insert all
spot lights in the scene graph before you render the scene once, and
just set ’on’ to FALSE if you want to toggle spot lights on/off on the
fly.
Since:
Coin 2.6
Member Data Documentation
SoSFBool SoShadowGroup::isActive Use this field to turn shadow rendering
for the subgraph on/off. Default value is TRUE.
SoSFFloat SoShadowGroup::intensity Not used yet. Provided for TGS Inventor
compatibility.
SoSFFloat SoShadowGroup::precision Use 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.
SoSFFloat SoShadowGroup::quality Can 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::smoothBorder SoShadowGroup::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.
SoSFBool SoShadowGroup::shadowCachingEnabled Not used yet. Provided for TGS
Inventor compatibility.
SoSFFloat SoShadowGroup::visibilityNearRadius Can 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
SoSFFloat SoShadowGroup::visibilityRadius Can 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
SoSFEnum SoShadowGroup::visibilityFlag Determines how visibilityRadius and
visibilitNearRadius is used to calculate near and far clipping planes
for the shadow volume.
SoSFFloat SoShadowGroup::epsilon Epsilon 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.
SoSFFloat SoShadowGroup::threshold Can 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.
Author
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