SoGLRenderAction(3)

NAME
SoGLRenderAction - The SoGLRenderAction class renders the scene graph with OpenGL calls.

SYNOPSIS

#include <Inventor/actions/SoGLRenderAction.h>

Inherits SoAction.

Inherited by SoBoxHighlightRenderAction, and SoLineHighlightRenderAction.

  Public Types
enum TransparencyType { SCREEN_DOOR, ADD, DELAYED_ADD, SORTED_OBJECT_ADD, BLEND, DELAYED_BLEND, SORTED_OBJECT_BLEND, SORTED_OBJECT_SORTED_TRIANGLE_ADD, SORTED_OBJECT_SORTED_TRIANGLE_BLEND, NONE, SORTED_LAYERS_BLEND }
enum TransparentDelayedObjectRenderType { ONE_PASS, NONSOLID_SEPARATE_BACKFACE_PASS }
enum AbortCode { CONTINUE, ABORT, PRUNE, DELAY }
enum SortedObjectOrderStrategy { BBOX_CENTER, BBOX_CLOSEST_CORNER, BBOX_FARTHEST_CORNER, CUSTOM_CALLBACK }
typedef AbortCode SoGLRenderAbortCB(void *userdata)

  Public Member Functions
virtual SoType getTypeId (void) const
SoGLRenderAction (const SbViewportRegion &viewportregion)
virtual ~SoGLRenderAction (void)
void setViewportRegion (const SbViewportRegion &newregion)
const SbViewportRegion & getViewportRegion (void) const
void setUpdateArea (const SbVec2f &origin, const SbVec2f &size)
void getUpdateArea (SbVec2f &origin, SbVec2f &size) const
void setAbortCallback (SoGLRenderAbortCB *const func, void *const userdata)
void getAbortCallback (SoGLRenderAbortCB *&func_out, void *&userdata_out) const
void setTransparencyType (const TransparencyType type)
TransparencyType getTransparencyType (void) const
void setTransparentDelayedObjectRenderType (TransparentDelayedObjectRenderType type)
TransparentDelayedObjectRenderType getTransparentDelayedObjectRenderType (void) const
void setSmoothing (const SbBool smooth)
SbBool isSmoothing (void) const
void setNumPasses (const int num)
int getNumPasses (void) const
void setPassUpdate (const SbBool flag)
SbBool isPassUpdate (void) const
void setPassCallback (SoGLRenderPassCB *const func, void *const userdata)
void setCacheContext (const uint32_t context)
uint32_t getCacheContext (void) const
void addDelayedPath (SoPath *path)
SbBool isRenderingDelayedPaths (void) const
SbBool handleTransparency (SbBool istransparent=FALSE)
void setCurPass (const int passnum, const int numpasses)
int getCurPass (void) const
SbBool abortNow (void)
void setRenderingIsRemote (SbBool isremote)
SbBool getRenderingIsRemote (void) const
virtual void invalidateState (void)
void addPreRenderCallback (SoGLPreRenderCB *func, void *userdata)
void removePreRenderCallback (SoGLPreRenderCB *func, void *userdata)
void setSortedLayersNumPasses (int num)
int getSortedLayersNumPasses (void) const
void setSortedObjectOrderStrategy (const SortedObjectOrderStrategy strategy, SoGLSortedObjectOrderCB *cb=NULL, void *closure=NULL)
void setDelayedObjDepthWrite (SbBool write)
SbBool getDelayedObjDepthWrite (void) const
SbBool isRenderingTranspPaths (void) const
SbBool isRenderingTranspBackfaces (void) const

  Static Public Member Functions
static SoType getClassTypeId (void)
static void addMethod (const SoType type, SoActionMethod method)
static void enableElement (const SoType type, const int stackindex)
static void initClass (void)

  Protected Member Functions
virtual const SoEnabledElementsList & getEnabledElements (void) const
virtual void beginTraversal (SoNode *node)
virtual void endTraversal (SoNode *node)

  Static Protected Member Functions
static SoEnabledElementsList * getClassEnabledElements (void)
static SoActionMethodList * getClassActionMethods (void)

  Additional Inherited Members

Detailed Description

The SoGLRenderAction class renders the scene graph with OpenGL calls. Applying this method at a root node for a scene graph, path or path list will render all geometry contained within that instance to the current OpenGL context.

Member Typedef Documentation

  typedef SoGLRenderAction::SoGLRenderAbortCB
Abort callbacks should be of this type.

See also
    setAbortCallback()

Member Enumeration Documentation

  enum SoGLRenderAction::TransparencyType
Various settings for how to do rendering of transparent objects in the scene. Some of the settings will provide faster rendering, while others give you better quality rendering.

Note that doing correct rendering of multiple transparent objects often fails, because to be 100% correct, all polygons needs to be rendered in sorted order, and polygons can't intersect each other. In a dynamic scene graph it is often impossible to guarantee that no polygons intersect, and finding an algorithm that does correct sorting of polygons for all possible cases is very hard and time-consuming.

The highest quality transparency mode in the original SGI / TGS Open Inventor is SoGLRenderAction::SORTED_OBJECT_BLEND, where all transparent objects are rendered in sorted order in a rendering pass after all opaque objects. However, this mode does not sort the polygons, and if you have an object where some polygon A is behind some other polygon B, the transparency will only be correct if A happens to be rendered before B. For other camera angles, where B is behind A, the transparency will not be correct.

In Coin we have a new transparency mode that solves some of these problems: SoGLRenderAction::SORTED_OBJECT_SORTED_TRIANGLE_BLEND. In addition to sorting the objects, all polygons inside each object is also sorted back-to-front when rendering. But, if you have intersecting objects and/or intersecting polygons, even this transparency mode will fail. Also, because of the polygon sorting, this transparency mode is quite slow. It is possible to speed things up using the SoTransparencyType node, though, which enables you to set different transparency modes for different parts of the scene graph. If you have only have a few objects where you need to sort the polygons, you can use SoGLRenderAction::SORTED_OBJECT_SORTED_TRIANGLE_BLEND for those, and for instance SoGLRenderAction::SORTED_OBJECT_BLEND for all other transparent objects.

The highest quality transparency mode in Coin is SoGLRenderAction::SORTED_LAYERS_BLEND. It is also the only mode that overrides all other modes in the scene graph.

(One important note about this mode: we've had reports from users that some OpenGL drivers -- possibly particular for some Mac OS X systems -- significantly degrades rendering performance. So be careful and test your application on a wide variety of runtime systems when using SoGLRenderAction::SORTED_LAYERS_BLEND.)

See also
    SoTransparencyType

Enumerator

SCREEN_DOOR
    Transparent triangles are rendered with a dither pattern. This is a fast (on most GFX cards) but not-so-high-quality transparency mode.

One particular feature of this mode is that you are guaranteed that it always renders the transparent parts of the scene correct with regard to internal depth ordering of objects / polygons, something which is not the case for any other transparency mode.

Polygons rendered with only transparent textures are not shown as being transparent when using this mode. The reason being that the SoGLRenderAction::SCREEN_DOOR mode is working on polygons, not pixels. To render polygons with dither pattern, a material node has to be inserted into the scene graph with its transparency field set.

ADD Transparent objects are rendered using additive alpha blending. Additive blending is probably mostly used to create special transparency effects. The new pixel color is calculated as the current pixel color plus the source pixel color multiplied with the source pixel alpha value.

DELAYED_ADD
    Transparent objects are rendered using additive alpha blending, in a second rendering pass with depth buffer updates disabled.

SORTED_OBJECT_ADD
    Transparent objects are rendered using additive alpha blending. Opaque objects are rendered first, and transparent objects are rendered back to front with z-buffer updates disabled.

BLEND
    Transparent objects are rendered using multiplicative alpha blending.

Multiplicative alpha blending is the blending type that is most often used to render transparent objects. The new pixel value is calculated as the old pixel color multiplied with one minus the source alpha value, plus the source pixel color multiplied with the source alpha value.

We recommend that you use this transparency mode if you have only one transparent object in your scene, and you know that it will be rendered after the opaque objects.

DELAYED_BLEND
    Transparent objects are rendered using multiplicative alpha blending, in a second rendering pass with depth buffer updates disabled.

Use this transparency type when you have one transparent object, or several transparent object that you know will never overlap (when projected to screen). Since the transparent objects are rendered after opaque ones, you'll not have to worry about putting the transparent objects at the end of your scene graph. It will not be as fast as the SoGLRenderAction::BLEND transparency type, of course, since the scene graph is traversed twice.

SORTED_OBJECT_BLEND
    Transparent objects are rendered using multiplicative alpha blending, Opaque objects are rendered first, and transparent objects are rendered back to front with z-buffer updates disabled.

Use this transparency mode when you have several transparent object that you know might overlap (when projected to screen). This method will require 1 + num_transparent_objects rendering passes. Path traversal is used when rendering transparent objects, of course, but it might still be slow if you have lots of state changes before your transparent object. When using this mode, we recommend placing the transparent objects as early as possible in the scene graph to minimize traversal overhead.

SORTED_OBJECT_SORTED_TRIANGLE_ADD
    This transparency type is a Coin extension versus the original SGI Open Inventor API.

Transparent objects are rendered back to front, and triangles in each object are sorted back to front before rendering.

See description for SoGLRenderAction::SORTED_OBJECT_SORTED_TRIANGLE_BLEND for more information about this transparency type.

SORTED_OBJECT_SORTED_TRIANGLE_BLEND
    This transparency type is a Coin extension versus the original SGI Open Inventor API.

Transparent objects are rendered back to front, and triangles in each object are sorted back to front before rendering.

Use this transparency type when you have one (or more) transparent object(s) where you know triangles might overlap inside the object. This transparency type might be very slow if you have an object with lots of triangles, since all triangles have to be sorted before rendering, and an unoptimized rendering loop is used when rendering. Lines and points are not sorted before rendering. They are rendered as in the normal SoGLRenderAction::SORTED_OBJECT_BLEND transparency type.

Please note that this transparency mode does not guarantee 'correct' transparency rendering. It is almost impossible to find an algorithm that will sort triangles correctly in all cases, and intersecting triangles are not handled. Also, since each object is handled separately, two intersecting object will lead to incorrect transparency.

NONE
    This transparency type is a Coin extension versus the Open Inventor API.

Turns off transparency for objects, even if transparency is set using an SoMaterial node.

Since
    Coin 1.0

SORTED_LAYERS_BLEND
    This transparency type is a Coin extension versus the original SGI Open Inventor API.

By using this transparency type, the SoGLRenderAction will render normal and intersecting transparent objects correctly independent of rendering order. It is the only transparency type rendering mode which is guaranteed to do so.

This mode is different from all other modes in that it overrides the SoTransparencyType nodes in the scene graph; all objects are drawn using SoGLRenderAction::SORTED_LAYERS_BLEND.

There are currently two separate code paths for this mode. Both paths are heavily based on OpenGL extensions. The first method is based on extensions which are only available on NVIDIA chipsets (GeForce3 and above, except GeForce4 MX). These extensions are GL_NV_texture_shader, GL_NV_texture_rectangle or GL_EXT_texture_rectangle, GL_NV_register_combiners, GL_ARB_shadow and GL_ARB_depth_texture. Please note that this transparency type occupy all four texture units on the NVIDIA card for all the rendering passes, except the first. Textured surfaces will therefore only be textured if they are not occluded by another transparent surface.

The second method utilizes the GL_ARB_fragment_program extension. This extension is currently supported by the GeForceFX family and the Radeon 9500 and above. This technique is faster than the pure NVIDIA method. The fragment program method will automatically be chosen if possible. Please note that one should beware not to place the near-plane too close to the camera due to the lack of floating point precision control in fragment programs. Doing so may lead to loss of precision around the edges and 'jaggedness' of the transparent geometry.

Setting the environment variable COIN_SORTED_LAYERS_USE_NVIDIA_RC to '1' will force the use of former code path instead of the latter, even if it is available.

A rendering context with >= 24 bits depth buffer and 8 bits alpha channel must be the current rendering context for this blending mode to actually become activated. If the current rendering canvas does not have these properties, Coin will fall back on a simpler transparency handling mode. If you are using one of the window-system binding libraries provided by Kongsberg Oil & Gas Technologies, e.g. SoXt, SoQt or SoWin, you will need to explicitly enable this in your viewer. See the API documentation of the setAlphaChannel() method of either SoXtGLWidget, SoQtGLWidget or SoWinGLWidget.

The detection of whether or not the SoGLRenderAction::SORTED_LAYERS_BLEND mode can be used will be done automatically by the Coin internals. If one or more of the necessary conditions listed above are unavailable, SoGLRenderAction::SORTED_OBJECT_BLEND will be used as the transparency type instead.

To be able to render correct transparency independent of object order, one have to render in multiple passes. This technique is based on depth-peeling which strips away depth layers with each successive pass. The number of passes is therefore an indication of how deep into the scene transparent surfaces will be rendered with transparency. A higher number will lead to a lower frame rate but higher quality for scenes with a lot of transparent surfaces. The default number of passes is '4'. This number can be specified using the SoGLRenderAction::setSortedLayersNumPasses() or by letting the environment variable COIN_NUM_SORTED_LAYERS_PASSES or OIV_NUM_SORTED_LAYERS_PASSES specify the number of passes.

A more detailed presentation of the algorithm is written by Cass Everitt at NVIDIA;

Since
    Coin 2.2

    TGS Inventor 4.0

  enum SoGLRenderAction::TransparentDelayedObjectRenderType
Enumerates the render types of transparent objects.

Enumerator

ONE_PASS
    Normal one pass rendering. This might cause artifacts for non-solid objects.

NONSOLID_SEPARATE_BACKFACE_PASS
    Non-solid objects are handled in an extra rendering pass. Back facing polygons are rendered in the first pass, and the front facing in the second pass.

  enum SoGLRenderAction::AbortCode
The return codes which an SoGLRenderAbortCB callback function should use.

See also
    setAbortCallback()

Enumerator

CONTINUE
    Continue rendering as usual.

ABORT
    Abort the rendering action immediately.

PRUNE
    Do not render the current node or any of its children, but continue the rendering traversal.

DELAY
    Delay rendering of the current node (and its children) until the next rendering pass.

  enum SoGLRenderAction::SortedObjectOrderStrategy
Used for enumerating the different transparency sorting strategies.

See also
    setSortedObjectOrderStrategy().

Since
    Coin 2.5

Enumerator

BBOX_CENTER
    Do the sorting based on the center of the object bounding box.

See also
    setSortedObjectOrderStrategy().

Since
    Coin 2.5

BBOX_CLOSEST_CORNER
    Do the sorting based on the bounding box corner closest to the camera.

See also
    setSortedObjectOrderStrategy().

Since
    Coin 2.5

BBOX_FARTHEST_CORNER
    Do the sorting based on the bounding box corner farthest from the camera.

See also
    setSortedObjectOrderStrategy().

Since
    Coin 2.5

CUSTOM_CALLBACK
    Use a custom callback to determine the sorting order.

See also
    setSortedObjectOrderStrategy().

Since
    Coin 2.5

Constructor & Destructor Documentation

  SoGLRenderAction::SoGLRenderAction (const SbViewportRegion & viewportregion)
Constructor. Sets up the render action for rendering within the given viewportregion.

  SoGLRenderAction::~SoGLRenderAction (void) [virtual]
Destructor.

Member Function Documentation

  SoType SoGLRenderAction::getTypeId (void) const [virtual]
Returns the type identification of an object derived from a class inheriting SoAction. This is used for runtime type checking and 'downward' casting.

Implements SoAction.

Reimplemented in SoBoxHighlightRenderAction, and SoLineHighlightRenderAction.

  SoType SoGLRenderAction::getClassTypeId (void) [static]
This static method returns the SoType object associated with objects of this class.

  void SoGLRenderAction::addMethod (const SoType type, SoActionMethod method) [static]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  void SoGLRenderAction::enableElement (const SoType type, const int stackindex) [static]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  const SoEnabledElementsList & SoGLRenderAction::getEnabledElements (void) const [protected], [virtual]
Returns list of enabled elements.

Reimplemented from SoAction.

Reimplemented in SoBoxHighlightRenderAction, and SoLineHighlightRenderAction.

  SoEnabledElementsList * SoGLRenderAction::getClassEnabledElements (void) [static], [protected]
Returns list of enabled elements for this class. The enabledElements and methods variables are protected in the original OIV API. This is not such a good idea, since exposed static class member variables is a major grievance with regard to Win32 DLLs. This function is an extension for Coin, and it is not available in the original SGI Open Inventor v2.1 API.

  SoActionMethodList * SoGLRenderAction::getClassActionMethods (void) [static], [protected]
Returns list of action methods for this class. The enabledElements and methods variables are protected in the original OIV API. This is not such a good idea, since exposed static class member variables is a major grievance with regard to Win32 DLLs. This function is an extension for Coin, and it is not available in the original SGI Open Inventor v2.1 API.

  void SoGLRenderAction::initClass (void) [static]
Initializes the runtime type system for this class, and sets up the enabled elements and action method list.

  void SoGLRenderAction::setViewportRegion (const SbViewportRegion & newregion)
Sets the viewport region for rendering. This will then override the region passed in with the constructor.

  const SbViewportRegion & SoGLRenderAction::getViewportRegion (void) const
Returns the viewport region for the rendering action.

  void SoGLRenderAction::setUpdateArea (const SbVec2f & origin, const SbVec2f & size)
Sets the area of the OpenGL context canvas we should render into.

The coordinates for origin and size should be normalized to be within [0.0, 1.0]. The default settings are <0.0, 0.0> for the origin and <1.0, 1.0> for the size, using the full size of the rendering canvas.

  void SoGLRenderAction::getUpdateArea (SbVec2f & origin, SbVec2f & size) const
Returns information about the area of the rendering context window to be updated.

  void SoGLRenderAction::setAbortCallback (SoGLRenderAbortCB *const func, void *const userdata)
Sets the abort callback. The abort callback is called by the action for each node during traversal to check for abort conditions.

The callback method should return one of the SoGLRenderAction::AbortCode enum values to indicate how the action should proceed further.

Since the client SoGLRenderAbortCB callback function only has a single void* argument for the userdata, one has to do some additional work to find out which node the callback was made for. One can do this by for instance passing along the action pointer as userdata, and then call the SoGLRenderAction::getCurPath() method. The tail of the path will then be the last traversed node. Like this:

// set up so we can abort or otherwise intervene with the render
// traversal:
myRenderAction->setAbortCallback(MyRenderCallback, myRenderAction);
// [...]
SoGLRenderAction::AbortCode
MyRenderCallback(void * userdata)
{
  SoGLRenderAction * action = (SoGLRenderAction *)userdata;
  SoNode * lastnode = action->getCurPath()->getTail();
  // [...]
  return SoGLRenderAction::CONTINUE;
}

See also
    SoGLRenderAction::AbortCode

  void SoGLRenderAction::getAbortCallback (SoGLRenderAbortCB *& func_out, void *& userdata_out) const
Returns the abort callback settings.

See also
    setAbortCallback

Since
    Coin 3.0

  void SoGLRenderAction::setTransparencyType (const TransparencyType type)
Sets the transparency rendering method for transparent objects in the scene graph.

See also
    SoGLRenderAction::TransparencyType

  SoGLRenderAction::TransparencyType SoGLRenderAction::getTransparencyType (void) const
Returns the transparency rendering type.

  void SoGLRenderAction::setTransparentDelayedObjectRenderType (TransparentDelayedObjectRenderType type)
Sets the render type of delayed or sorted transparent objects. Default is ONE_PASS.

Since
    Coin 3.0

  SoGLRenderAction::TransparentDelayedObjectRenderType SoGLRenderAction::getTransparentDelayedObjectRenderType (void) const
Returns the render type of delayed or sorted transparent objects.

Since
    Coin 3.0

  void SoGLRenderAction::setSmoothing (const SbBool smooth)
Sets (or unsets) smoothing. If the smoothing flag is on, Coin will try to use built-in features from the OpenGL implementation to smooth the appearance of otherwise jagged line and point primitives, calling

    glEnable(GL_POINT_SMOOTH);
    glEnable(GL_LINE_SMOOTH);

...before rendering the scene.

This is a simple (and computationally non-intensive) way of doing anti-aliasing.

Default value for this flag is to be off.

  SbBool SoGLRenderAction::isSmoothing (void) const
Returns whether smoothing is set or not.

  void SoGLRenderAction::setNumPasses (const int num)
Sets the number of rendering passes. Default is 1, anything greater will enable antialiasing through the use of an OpenGL accumulation buffer.

  int SoGLRenderAction::getNumPasses (void) const
Returns the number of rendering passes done on updates.

  void SoGLRenderAction::setPassUpdate (const SbBool flag)
Sets whether each pass should render to screen or not.

  SbBool SoGLRenderAction::isPassUpdate (void) const
Returns the value of the 'show intermediate updates' flag.

See also
    setPassUpdate()

  void SoGLRenderAction::setPassCallback (SoGLRenderPassCB *const func, void *const userdata)
Sets the pass callback. The callback is called between each rendering pass.

  void SoGLRenderAction::setCacheContext (const uint32_t context)
Sets the OpenGL cache context key, which is used for deciding when to share OpenGL display lists.

Each SoGLRenderAction has a cache context id. This can be set using SoGLRenderAction::setCacheContext(). The cache context id must be unique, so that different texture objects and display lists are created for incompatible GL contexts. For instance, when SoGLRenderAction traverses an SoTexture2 node, the node checks if it has a texture object created for the cache context. If not, a new texture object will be created and used when rendering.

See also
    SoGLCacheContextElement::getUniqueCacheContext()

  uint32_t SoGLRenderAction::getCacheContext (void) const
Returns the cache context key for this rendering action instance.

  void SoGLRenderAction::addDelayedPath (SoPath * path)
Adds a path to the list of paths to render after the current pass.

  SbBool SoGLRenderAction::isRenderingDelayedPaths (void) const
Returns a flag indicating whether or not we are currently rendering from the list of delayed paths of the scene graph.

  SbBool SoGLRenderAction::handleTransparency (SbBool istransparent = FALSE)
Used by shape nodes or others which need to know whether or not they should immediately render themselves or if they should wait until the next pass. It also enables/disabled blending based on the istransparent parameter.

If you're using an SoCallback or a non-shape node to render your geometry, you can use this function to make sure your node is only rendered once. This function consider the istransparent parameter, and when TRUE it will return TRUE on the first pass, and FALSE on the second pass. For non-transparent objects it returns FALSE on the first pass, TRUE on the second.

Please note that this function considers the current transparency type when deciding what to do. It will delay rendering only when the transparency type is DELAYED_* or SORTED_OBJECT_*. For other transparency types, transparent objects are rendered in the same pass as opaque objects.

  void SoGLRenderAction::setCurPass (const int passnum, const int numpasses)
Sets the current rendering pass to passnum. This can be used when antialiasing is controlled from outside the SoGLRenderAction instance. numpasses is the total number of rendering passes to be used.

Please note that this will disable any antialiasing set using the setNumPasses() method. You can reenable the internal antialiasing again by calling setNumPasses()

Since
    Coin 3.1

  int SoGLRenderAction::getCurPass (void) const
Returns the number of the current rendering pass.

  SbBool SoGLRenderAction::abortNow (void)
Returns TRUE if the render action should abort now based on user callback.

See also
    setAbortCallback()

  void SoGLRenderAction::setRenderingIsRemote (SbBool isremote)
Let SoGLRenderAction instance know if application is running on the local machine or if the rendering instructions are sent over the network.

The flag is used to optimize rendering. For instance should the display list caching strategy be influenced by this flag to be more aggressive with the caching when rendering instructions are passed over the network.

Default value is FALSE. The value of the flag will not be changed internally from the Coin library code, as it is meant to be controlled from client code -- typically from the SoQt / SoXt / SoWin / SoGtk libraries.

See also
    getRenderingIsRemote()

  SbBool SoGLRenderAction::getRenderingIsRemote (void) const
Returns whether or not the application is running remotely.

See also
    setRenderingIsRemote()

  void SoGLRenderAction::invalidateState (void) [virtual]
Invalidates the state, forcing it to be recreated at the next apply() invocation.

Reimplemented from SoAction.

  void SoGLRenderAction::addPreRenderCallback (SoGLPreRenderCB * func, void * userdata)
Adds a callback which is invoked right before the scene graph traversal starts. All necessary GL initialization is then done (e.g. the viewport is correctly set), and this callback can be useful to, for instance, clear the viewport before rendering, or draw a bitmap in the background before rendering etc.

The callback is only invoked once (before the first rendering pass) when multi pass rendering is enabled.

Please note that SoSceneManager usually adds a callback to clear the GL buffers in SoSceneManager::render(). So, if you plan to for instance draw an image in the color buffer using this callback, you should make sure that the scene manager doesn't clear the buffer. This can be done either by calling SoSceneManager::render() with both arguments FALSE, or, if you're using one of our GUI toolkits (SoXt/SoQt/SoGtk/SoWin), call setClearBeforeRender() on the viewer.

This method is an extension versus the Open Inventor API.

See also
    removePreRenderCallback().

  void SoGLRenderAction::removePreRenderCallback (SoGLPreRenderCB * func, void * userdata)
Removed a callback added with the addPreRenderCallback() method.

This method is an extension versus the Open Inventor API.

See also
    addPreRenderCallback()

  void SoGLRenderAction::setSortedLayersNumPasses (int num)
Sets the number of passes to render in SoGLRenderAction::SORTED_LAYERS_BLEND mode. Default number of passes is 4. This number can also be adjusted by setting the COIN_NUM_SORTED_LAYERS_PASSES or OIV_NUM_SORTED_LAYERS_PASSES environment variable.

  int SoGLRenderAction::getSortedLayersNumPasses (void) const
Returns the number of passes to render when in SoGLRenderAction::SORTED_LAYERS_BLEND mode.

  void SoGLRenderAction::setSortedObjectOrderStrategy (const SortedObjectOrderStrategy strategy, SoGLSortedObjectOrderCB * cb = NULL, void * closure = NULL)
Sets the strategy used for sorting transparent objects.

The CUSTOM_CALLBACK strategy enables the user to supply a callback which is called for each transparent shape. This strategy can be used if the built in sorting strategies aren't sufficient.

The callback should return a floating point value to be used when sorting the objects in Coin. This floating point value is interpreted as a distance to the camera, and objects with higher values will be sorted behind objects with lower values.

The callback will supply the SoGLRenderAction instance, and the path to the current object can be found using SoAction::getCurPath().

Since
    Coin 2.5

  void SoGLRenderAction::setDelayedObjDepthWrite (SbBool write)
Set whether depth buffer updates should be done when rendering delayed or sorted transparent objects.

Since
    Coin 3.0

  SbBool SoGLRenderAction::getDelayedObjDepthWrite (void) const
Return whether depth buffer updates should be done when rendering delayed or sorted transparent objects. Default is FALSE.

Since
    Coin 3.0

  SbBool SoGLRenderAction::isRenderingTranspPaths (void) const
Returns TRUE if the action is currently rendering delayed or sorted transparent objects.

Since
    Coin 3.0

  SbBool SoGLRenderAction::isRenderingTranspBackfaces (void) const
Returns TRUE if the action is currently rendering back facing polygons in NONSOLID_SEPARATE_BACKFACE_PASS mode.

Since
    Coin 3.0

  void SoGLRenderAction::beginTraversal (SoNode * node) [protected], [virtual]
This virtual method is called from SoAction::apply(), and is the entry point for the actual scene graph traversal.

It can be overridden to initialize the action at traversal start, for specific initializations in the action subclasses inheriting SoAction.

Default method just calls traverse(), which any overridden implementation of the method must do too (or call SoAction::beginTraversal()) to trigger the scene graph traversal.

Reimplemented from SoAction.

  void SoGLRenderAction::endTraversal (SoNode * node) [protected], [virtual]
This virtual method can be overridden to execute code after the scene graph traversal. Default method does nothing.

Reimplemented from SoAction.

Author

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