SoShadowGroup

java.lang.Object
- com.openinventor.inventor.Inventor
- - com.openinventor.inventor.misc.SoBase
  - - com.openinventor.inventor.fields.SoFieldContainer
    - - com.openinventor.inventor.nodes.SoNode
      - com.openinventor.inventor.nodes.SoGroup
        
        com.openinventor.inventor.nodes.SoShadowGroup

All Implemented Interfaces:: SafeDisposable

public class SoShadowGroup
extends SoGroup

Shadow casting group node. This group node performs real-time shadow casting. Because shadows depends on a lot of OpenInventor elements, it is recommended to put children of this group under a SoSeparator in order to have a cache. Each shape within this group will be included in the shadow casting computation. A shape may cast a shadow on other shapes or on itself (self-shadowing), and/or may be shadowed by other shapes within the group. The current shadow style is used to determine if shapes cast a shadow and/or can be shadowed (see SoShadowStyle).

This class defines two shadowing methods which can be selected with the method field:

SHADOW_MAP: In this mode, shadows are not filtered and will display aliasing. Futhermore, it is not compatbile with VolumeViz nodes. All directional lights and spotlights (but not point lights) above this group node are used for computing the shadows. Adding lights as children of this group node will give incorrect results (lights must be defined above this node). Even when using the best quality setting (see quality), some aliasing artifacts will appear if you zoom in very close to the scene. Another way to increase the shadowing quality (decrease the aliasing effects), is to specify a spherical region centered at the camera position within which the shadowing will be computed (see visibilityRadius). The smaller the radius of this sphere, the better the shadow quality. This parameter is particularly useful for walk-through scenes.

VARIANCE_SHADOW_MAP : This mode allows to display soft shadows. The smoothFactor field can be used to increase or decrease the softness. Contrary to the SHADOW_MAP method, aliasing won't be displayed but on large scene, shadows will progressively fade away. Increasing quality will reduce this problem. Only the last on state directional light is used during rendering, other lights are ignored.

Shaders
Only the VARIANCE_SHADOW_MAP method is available with shaders (custom or internal). In order to use shadows with user defined GLSL shaders (SoShaderProgram or SoVolumeShader), the following functions must be used in the shader programs.
In the vertex shader:

void OivSetupShadowVertex(): Must be called in the vertex shader.

In the fragment shader:

float OivComputeShadow(): Returns a scalar in [0-1]. 0 means fragment is fully shadowed, 1 means no shadow. Should be used to modify the fragment color.
void OivGenerateShadowMap(): Must be called during the shadowmap pass in order to create the shadowmap. During this pass, the shader must not write to gl_FragData[0]. Use the uniform OivShadowPass to know when the shadowmap is being computed.

The following uniform is available in vertex and fragment shaders:

uniform bool OivShadowPass: Is true if the shadowmap is currently being rendered

The following code can be used as a skeleton for a GLSL shader that works with shadows:

 // The vertex shader:
 void OivSetupShadowVertex();
 void main()
 {
   ..userCode..
   //Needed for shadowing
   OivSetupShadowVertex();
 }
 
 // The fragment shader:
 //If true we are in shadowmap generation pass
 uniform bool OivShadowPass;
 
 void OivGenerateShadowMap();
 float OivComputeShadow();
 void main()
 {
   if ( !OivShadowPass ) {
     ..compute fragment color here..
     // Define the final color
     gl_FragData[0].xyz = fragColor.xyz * OivComputeShadow();
     gl_FragData[0].w = fragColor.w;
   }
   else {
     // Output the shadowmap during the shadow map pass
     OivGenerateShadowMap();
   }
 }

Transparency:
Transparent objects are treated as follows, depending on the transparency type:

ADD, BLEND: Transparent objects cast a shadow and are shadowed but the shadow intensity doesn't depend on the transparency value (the same shadow is displayed for full transparent shapes and opaque shapes).
ALL SORTED, ALL DELAYED, and SCREEN_DOOR: Same as previous case for VARIANCE_SHADOW_MAP. For SHADOW_MAP method transparent objects neither cast a shadow nor are shadowed.
SORTED_PIXELS_BLEND: This transparency mode is not compatible with SoShadowGroup. No shadows are computed.

Texture units:
In SHADOW_MAP mode this node reserves texture units FXVIZ_SHADOW_TEXTURE_UNIT0 and FXVIZ_SHADOW_TEXTURE_UNIT1 for its rendering (see SoPreferences to set these). If these values are not set, texture units 1 and 2 are used. These values cannot be greater than 3.

In VARIANCE_SHADOW_MAP mode, this node reserves texture unit FXVIZ_SHADOW_TEXTURE_UNIT0 for its rendering (see SoPreferences to set these). If this value is not set the application can specify which texture units OpenInventor should automatically use by setting environment variables (see SoPreferences). The texture units between OIV_FIRST_RESERVED_TEXTURE_UNIT and OIV_FIRST_RESERVED_TEXTURE_UNIT+SoShaderProgram.getNumReservedTextures()-1 inclusive are reserved for internal OpenInventor use. If OIV_FIRST_RESERVED_TEXTURE_UNIT is not set, its default value is SoFragmentShader.getMaxTextureImageUnit()-SoShaderProgram.getNumReservedTextures(). Note: The value returned by SoShaderProgram.getNumReservedTextures() may change between OpenInventor versions. The total number of available texture units depends on the graphics hardware.

Hardware requirements:
NOTE: In SHADOW_MAP mode, at least the Multi-Texture and Texture Environment Combine OpenGL extensions must be supported by your graphics board. Otherwise no shadows will be computed. These extensions are now standard in OpenGL 1.3 and later.
The Shadow and Depth Texture OpenGL extensions (standard in OpenGL 1.4) are used if they are available and generally improve performance.
In order to increase quality and performance of the shadows, OpenGL PBuffers are used. PBuffers are a limited resource on some systems. Set OIV_PBUFFER_ENABLE to 0 to disallow use of PBuffers.

A DirectX 10 graphics board is needed to support VARIANCE_SHADOW_MAP.

Use the isSupported() static method to determine if the current graphics board supports shadowing.

Notes:

Geometry cannot receive shadows if lighting is disabled.
For example if an SoLightModel node sets the lighting model to BASE_COLOR.
Geometry cannot receive shadows if a texture is applied using the DECAL or REPLACE models.

Potential problems:
In SHADOW_MAP mode, performance issues and incorrect images have been observed with some OpenGL drivers due to the Texture Border Clamp OpenGL extension (standard in OpenGL 1.3), Try setting the OIV_TEXTURE_BORDER_CLAMP_ENABLE environment variable to 0 in this case.
With some graphics boards, especially older hardware like GeForce2, it may be necessary to also set the OIV_FORCE_DUAL_TEX_SHADOW environment variable to 1.

File format/default:

ShadowGroup {

isActive	true
isShapesBefore	false
intensity	0.5
precision	0.5
quality	0.5
shadowCachingEnabled	true
visibilityRadius	1.0
visibilityFlag	LONGEST_BBOX_EDGE_FACTOR
smoothFactor	1
minVariance	1e-5
method	SHADOW_MAP
lightBleedingReduction	0.01

}

See also:

SoShadowStyle

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`SoShadowGroup.ShadowingMethods` Shadowing techniques.
`static class`	`SoShadowGroup.VisibilityFlags` `visibilityRadius` interpretation

Nested classes/interfaces inherited from class com.openinventor.inventor.Inventor
Inventor.ConstructorCommand

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`ABSOLUTE_RADIUS` Deprecated. Use `SoShadowGroup.VisibilityFlags.ABSOLUTE_RADIUS` instead.
`SoSFFloat`	`intensity` Specifies the intensity of the shadow.
`SoSFBool`	`isActive` Activates/deactivates the shadowing.
`SoSFBool`	`isShapesBefore` Deprecated. As of Open Inventor 9620 See documentation for more details
`static int`	`LAST_METHOD` Deprecated. Use `SoShadowGroup.ShadowingMethods.LAST_METHOD` instead.
`SoSFFloat`	`lightBleedingReduction` Used only for VARIANCE_SHADOW_MAP.
`static int`	`LONGEST_BBOX_EDGE_FACTOR` Deprecated. Use `SoShadowGroup.VisibilityFlags.LONGEST_BBOX_EDGE_FACTOR` instead.
`SoSFEnum<SoShadowGroup.ShadowingMethods>`	`method` Specifies the shadowing technique to use.
`SoSFFloat`	`minVariance` Used only for VARIANCE_SHADOW_MAP.
`SoSFFloat`	`precision` Specifies the precision of the shadow.
`SoSFFloat`	`quality` Specifies the quality of the shadow.
`static int`	`SHADOW_MAP` Deprecated. Use `SoShadowGroup.ShadowingMethods.SHADOW_MAP` instead.
`SoSFBool`	`shadowCachingEnabled` Indicates if a cache should be used for computing the shadows.
`SoSFInt32`	`smoothFactor` Set the smoothness of shadows.
`static int`	`VARIANCE_SHADOW_MAP` Deprecated. Use `SoShadowGroup.ShadowingMethods.VARIANCE_SHADOW_MAP` instead.
`SoSFEnum<SoShadowGroup.VisibilityFlags>`	`visibilityFlag` Specifies how `visibilityRadius` is interpreted.
`SoSFFloat`	`visibilityRadius` Shadows are only computed within "visibility radius" distance from the camera position.

Fields inherited from class com.openinventor.inventor.nodes.SoGroup
boundingBoxIgnoring

Fields inherited from class com.openinventor.inventor.Inventor
VERBOSE_LEVEL, ZeroHandle

Constructor Summary

Constructors
Constructor and Description

SoShadowGroup()
Default constructor.

SoShadowGroup(int nChildren)
Constructor that takes approximate number of children.

Constructors
Constructor and Description
`SoShadowGroup()` Default constructor.
`SoShadowGroup(int nChildren)` Constructor that takes approximate number of children.

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static boolean`	`isSupported()` Calls isSupported(SoShadowGroup.ShadowingMethods.valueOf( SoShadowGroup.ShadowingMethods.SHADOW_MAP.getValue() )).
`static boolean`	`isSupported(SoShadowGroup.ShadowingMethods method)` Indicates if shadow casting is supported by your graphic board.

Methods inherited from class com.openinventor.inventor.nodes.SoGroup
addChild, findChild, getChild, getNumChildren, insertChild, removeAllChildren, removeChild, removeChild, replaceChild, replaceChild

Methods inherited from class com.openinventor.inventor.nodes.SoNode
affectsState, callback, copy, copy, distribute, doAction, getAlternateRep, getBoundingBox, getByName, getMatrix, getPrimitiveCount, getRenderUnitID, GLRender, GLRenderBelowPath, GLRenderInPath, GLRenderOffPath, grabEventsCleanup, grabEventsSetup, handleEvent, isBoundingBoxIgnoring, isOverride, pick, rayPick, search, setOverride, touch, write

Methods inherited from class com.openinventor.inventor.fields.SoFieldContainer
copyFieldValues, copyFieldValues, enableNotify, fieldsAreEqual, get, getAllFields, getEventIn, getEventOut, getField, getFieldName, hasDefaultValues, isNotifyEnabled, set, setToDefaults

Methods inherited from class com.openinventor.inventor.misc.SoBase
dispose, getEXTERNPROTO, getName, getPROTO, isDisposable, isSynchronizable, setName, setSynchronizable

Methods inherited from class com.openinventor.inventor.Inventor
getAddress, getNativeResourceHandle, startInternalThreads, stopInternalThreads

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - ABSOLUTE_RADIUS
```
@Deprecated
public static final int ABSOLUTE_RADIUS
```
    Deprecated. Use SoShadowGroup.VisibilityFlags.ABSOLUTE_RADIUS instead.
  - LONGEST_BBOX_EDGE_FACTOR
```
@Deprecated
public static final int LONGEST_BBOX_EDGE_FACTOR
```
    Deprecated. Use SoShadowGroup.VisibilityFlags.LONGEST_BBOX_EDGE_FACTOR instead.
  - SHADOW_MAP
```
@Deprecated
public static final int SHADOW_MAP
```
    Deprecated. Use SoShadowGroup.ShadowingMethods.SHADOW_MAP instead.
  - VARIANCE_SHADOW_MAP
```
@Deprecated
public static final int VARIANCE_SHADOW_MAP
```
    Deprecated. Use SoShadowGroup.ShadowingMethods.VARIANCE_SHADOW_MAP instead.
  - LAST_METHOD
```
@Deprecated
public static final int LAST_METHOD
```
    Deprecated. Use SoShadowGroup.ShadowingMethods.LAST_METHOD instead.
  - isActive
```
public final SoSFBool isActive
```
    Activates/deactivates the shadowing. If deactivated, this SoShadowGroup behaves like an SoGroup.
  - isShapesBefore
```
@Deprecated
public final SoSFBool isShapesBefore
```
    Deprecated. As of Open Inventor 9620 See documentation for more details
    
    Indicates that there are shapes before this group. Setting this value to true may slow down the rendering because it causes a depth buffer save at each frame. Used only for SHADOW_MAP method.Deprecated since Open Inventor 9620
    Only used for SHADOW_MAP method, which is deprecated. Please use VARIANCE_SHADOW_MAP instead.
  - intensity
```
public final SoSFFloat intensity
```
    Specifies the intensity of the shadow. 0 = lowest intensity (the shadow is invisible), 1 = highest intensity (the shadow is solid black).
  - precision
```
public final SoSFFloat precision
```
    Specifies the precision of the shadow. 0 = lowest precision, 1 = highest precision. With lower precisions, some parts of the scene may be unlit where they should be lit, or vice versa. Increasing the precision will reduce performance.
    NOTE: If your graphics driver does not support the required OpenGL extensions, you may see low precision results even when this field is set to the highest precision.
  - quality
```
public final SoSFFloat quality
```
    Specifies the quality of the shadow. 0 = lower quality, 1 = best quality.
    For VARIANCE_SHADOW_MAP quality may be greater than 1 (texture used for shadowmap rendering will be of size 2*quality*ViewportSize)
    Increasing the quality will reduce performance and increase memory consumption.
  - shadowCachingEnabled
```
public final SoSFBool shadowCachingEnabled
```
    Indicates if a cache should be used for computing the shadows. Using a cache will improve rendering performance if the lights of your scene and your scene under this group node do not change.
  - visibilityRadius
```
public final SoSFFloat visibilityRadius
```
    Shadows are only computed within "visibility radius" distance from the camera position. This radius equals:
    - the longest edge of the bounding box of the scene multiplied by visibilityRadius if visibilityFlag equals LONGEST_BBOX_EDGE_FACTOR.
    - visibilityRadius if visibilityFlag equals ABSOLUTE_RADIUS.
    When visibilityRadius = 1 and visibilityFlag = LONGEST_BBOX_EDGE_FACTOR (default values), shadowing is computed throughout the entire scene.
    Note: With VARIANCE_SHADOW_MAP method, try to increase the quality field first.
  - visibilityFlag
```
public final SoSFEnum<SoShadowGroup.VisibilityFlags> visibilityFlag
```
    Specifies how visibilityRadius is interpreted. Use enum VisibilityFlag. Default is LONGEST_BBOX_EDGE_FACTOR.
  - smoothFactor
```
public final SoSFInt32 smoothFactor
```
    Set the smoothness of shadows. Higher values give smoother shadows. Default is 1. Used only for VARIANCE_SHADOW_MAP method.
    
    Since:
    
    Open Inventor 8.1
  - minVariance
```
public final SoSFFloat minVariance
```
    Used only for VARIANCE_SHADOW_MAP. Increasing this value will decrease possible self-shadowing artifacts but will make shadows fade away. The default value is safe for most scenes. Increasing the quality field is also preferable before tweaking this value. A special case is for SoVolumeRender node which has a minimum of 0.001 or IVVR_SHADOW_MIN_VARIANCE if set. Default is 1e-5 and range is [0-1].
    
    Since:
    
    Open Inventor 8.1
  - lightBleedingReduction
```
public final SoSFFloat lightBleedingReduction
```
    Used only for VARIANCE_SHADOW_MAP. In some cases, a halo may appear around shadows intersecting each other. Increasing this value will decrease this effect. Default value is safe for most scenes. Default is 0.01 and range is [0-1].
    
    Since:
    
    Open Inventor 8.1
  - method
```
public final SoSFEnum<SoShadowGroup.ShadowingMethods> method
```
    Specifies the shadowing technique to use. . Default is SHADOW_MAP.
    
    Since:
    
    Open Inventor 8.1
- Constructor Detail
  - SoShadowGroup
```
public SoShadowGroup(int nChildren)
```
    Constructor that takes approximate number of children.
  - SoShadowGroup
```
public SoShadowGroup()
```
    Default constructor.
- Method Detail
  - isSupported
```
public static boolean isSupported()
```
    Calls isSupported(SoShadowGroup.ShadowingMethods.valueOf( SoShadowGroup.ShadowingMethods.SHADOW_MAP.getValue() )).
  - isSupported
```
public static boolean isSupported(SoShadowGroup.ShadowingMethods method)
```
    Indicates if shadow casting is supported by your graphic board. When using a debug build of Open Inventor, some "no context available" warning messages may be generated. You can ignore them or see SoGLExtension for an example of using SoGLContext to avoid them.

Class SoShadowGroup

Nested Class Summary

Nested classes/interfaces inherited from class com.openinventor.inventor.Inventor

Field Summary

Fields inherited from class com.openinventor.inventor.nodes.SoGroup

Fields inherited from class com.openinventor.inventor.Inventor

Constructor Summary

Method Summary

Methods inherited from class com.openinventor.inventor.nodes.SoGroup

Methods inherited from class com.openinventor.inventor.nodes.SoNode

Methods inherited from class com.openinventor.inventor.fields.SoFieldContainer

Methods inherited from class com.openinventor.inventor.misc.SoBase

Methods inherited from class com.openinventor.inventor.Inventor

Methods inherited from class java.lang.Object

Field Detail

ABSOLUTE_RADIUS

LONGEST_BBOX_EDGE_FACTOR

SHADOW_MAP

VARIANCE_SHADOW_MAP

LAST_METHOD

isActive

isShapesBefore

intensity

precision

quality

shadowCachingEnabled

visibilityRadius

visibilityFlag

smoothFactor

minVariance

lightBleedingReduction

method

Constructor Detail

SoShadowGroup

SoShadowGroup

Method Detail

isSupported

isSupported