SoGLRenderAction Class Reference

The SoGLRenderAction class renders the scene graph with OpenGL calls. More...

#include <Inventor/actions/SoGLRenderAction.h>

Inheritance diagram for SoGLRenderAction:

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 Types inherited from SoAction
enum	AppliedCode { NODE = 0, PATH = 1, PATH_LIST = 2 }
enum	PathCode { NO_PATH = 0, IN_PATH = 1, BELOW_PATH = 2, OFF_PATH = 3 }

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
Public Member Functions inherited from SoAction
virtual	~SoAction (void)
virtual SbBool	isOfType (SoType type) const
virtual void	apply (SoNode *root)
virtual void	apply (SoPath *path)
virtual void	apply (const SoPathList &pathlist, SbBool obeysrules=FALSE)
void	apply (SoAction *beingApplied)
AppliedCode	getWhatAppliedTo (void) const
SoNode *	getNodeAppliedTo (void) const
SoPath *	getPathAppliedTo (void) const
const SoPathList *	getPathListAppliedTo (void) const
const SoPathList *	getOriginalPathListAppliedTo (void) const
SbBool	isLastPathListAppliedTo (void) const
PathCode	getPathCode (int &numindices, const int *&indices)
void	traverse (SoNode *const node)
SbBool	hasTerminated (void) const
const SoPath *	getCurPath (void)
SoState *	getState (void) const
PathCode	getCurPathCode (void) const
virtual SoNode *	getCurPathTail (void)
void	usePathCode (int &numindices, const int *&indices)
void	pushCurPath (const int childindex, SoNode *node=NULL)
void	popCurPath (const PathCode prevpathcode)
void	pushCurPath (void)
void	popPushCurPath (const int childindex, SoNode *node=NULL)
void	popCurPath (void)
void	switchToPathTraversal (SoPath *path)
void	switchToNodeTraversal (SoNode *node)

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)
Static Public Member Functions inherited from SoAction
static void	initClass (void)
static void	initClasses (void)
static SoType	getClassTypeId (void)
static void	nullAction (SoAction *action, SoNode *node)

Protected Member Functions
virtual const SoEnabledElementsList &	getEnabledElements (void) const
virtual void	beginTraversal (SoNode *node)
virtual void	endTraversal (SoNode *node)
Protected Member Functions inherited from SoAction
	SoAction (void)
void	setTerminated (const SbBool flag)
virtual SbBool	shouldCompactPathList (void) const

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

Additional Inherited Members
Protected Attributes inherited from SoAction
SoState *	state
SoActionMethodList *	traversalMethods

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 pathlist will render all geometry contained within that instance to the current OpenGL context.

Member Typedef Documentation

SoGLRenderAbortCB

typedef SoGLRenderAction::SoGLRenderAbortCB

Abort callbacks should be of this type.

See also

setAbortCallback()

Member Enumeration Documentation

TransparencyType

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 scenegraph.

(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 run-time 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 SCREEN_DOOR mode is working on polygons, not pixels. To render polygons with dither pattern, a material node has to be inserted into the scenegraph with it's 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	SoGLRenderAction::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 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 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 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 scenegraph; all objects are drawn using 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 utilise 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 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 framerate 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; "Interactive Order-Independent Transparency" http:://developer.nvidia.com/object/order_independent_transparency.html Since Coin 2.2 TGS Inventor 4.0

TransparentDelayedObjectRenderType

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. Backfacing polygons are rendered in the first pass, and the front facing in the second pass.

AbortCode

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.

SortedObjectOrderStrategy

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::SoGLRenderAction

(

const SbViewportRegion &

viewportregion

)

Constructor. Sets up the render action for rendering within the given viewportregion.

~SoGLRenderAction()

SoGLRenderAction::~SoGLRenderAction ( void  )

virtual

Destructor.

Member Function Documentation

getTypeId()

SoType SoGLRenderAction::getTypeId ( void  ) const

virtual

Returns the type identification of an action derived from a class inheriting SoAction. This is used for run-time type checking and "downward" casting.

Usage example:

void bar(SoAction * action)
{
  if (action->getTypeId() == SoGLRenderAction::getClassTypeId()) {
    // safe downward cast, know the type
    SoGLRenderAction * glrender = (SoGLRenderAction *)action;
  }
  return; // ignore if not renderaction
}

For application programmers wanting to extend the library with new actions: this method needs to be overridden in all subclasses. This is typically done as part of setting up the full type system for extension classes, which is usually accomplished by using the pre-defined macros available through Inventor/nodes/SoSubAction.h: SO_ACTION_SOURCE, SO_ACTION_INIT_CLASS and SO_ACTION_CONSTRUCTOR.

For more information on writing Coin extensions, see the SoAction class documentation.

Returns the actual type id of an object derived from a class inheriting SoAction. Needs to be overridden in all subclasses.

Implements SoAction.

Reimplemented in SoBoxHighlightRenderAction, and SoLineHighlightRenderAction.

addMethod()

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.

enableElement()

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.

getEnabledElements()

const SoEnabledElementsList & SoGLRenderAction::getEnabledElements ( void  ) const

protectedvirtual

Returns a list of the elements used by action instances of this class upon traversal operations.

Reimplemented from SoAction.

Reimplemented in SoBoxHighlightRenderAction, and SoLineHighlightRenderAction.

setViewportRegion()

void SoGLRenderAction::setViewportRegion

(

const SbViewportRegion &

newregion

)

Sets the viewport region for rendering. This will then override the region passed in with the constructor.

getViewportRegion()

const SbViewportRegion & SoGLRenderAction::getViewportRegion

(

void

)

const

Returns the viewport region for the rendering action.

setUpdateArea()

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.

getUpdateArea()

void SoGLRenderAction::getUpdateArea	(	SbVec2f &	origin,
		SbVec2f &	size
	)		const

Returns information about the area of the rendering context window to be updated.

setAbortCallback()

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

getAbortCallback()

void SoGLRenderAction::getAbortCallback	(	SoGLRenderAbortCB *&	func_out,
		void *&	userdata_out
	)		const

Returns the abort callback settings.

See also

setAbortCallback

Since

Coin 3.0

setTransparencyType()

void SoGLRenderAction::setTransparencyType

(

const TransparencyType

type

)

Sets the transparency rendering method for transparent objects in the scene graph.

See also

SoGLRenderAction::TransparencyType

getTransparencyType()

SoGLRenderAction::TransparencyType SoGLRenderAction::getTransparencyType

(

void

)

const

Returns the transparency rendering type.

setTransparentDelayedObjectRenderType()

void SoGLRenderAction::setTransparentDelayedObjectRenderType

(

TransparentDelayedObjectRenderType

type

)

Sets the render type of delayed or sorted transparent objects. Default is ONE_PASS.

Since

Coin 3.0

getTransparentDelayedObjectRenderType()

SoGLRenderAction::TransparentDelayedObjectRenderType SoGLRenderAction::getTransparentDelayedObjectRenderType

(

void

)

const

Returns the render type of delayed or sorted transparent objects.

Since

Coin 3.0

setSmoothing()

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.

isSmoothing()

SbBool SoGLRenderAction::isSmoothing

(

void

)

const

Returns whether smoothing is set or not.

setNumPasses()

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.

getNumPasses()

int SoGLRenderAction::getNumPasses

(

void

)

const

Returns the number of rendering passes done on updates.

setPassUpdate()

void SoGLRenderAction::setPassUpdate

(

const SbBool

flag

)

Sets whether each pass should render to screen or not.

isPassUpdate()

SbBool SoGLRenderAction::isPassUpdate

(

void

)

const

Returns the value of the "show intermediate updates" flag.

See also

setPassUpdate()

setPassCallback()

void SoGLRenderAction::setPassCallback	(	SoGLRenderPassCB *const	func,
		void *const	userdata
	)

Sets the pass callback. The callback is called between each rendering pass.

setCacheContext()

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 uncompatible 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()

getCacheContext()

uint32_t SoGLRenderAction::getCacheContext

(

void

)

const

Returns the cache context key for this rendering action instance.

addDelayedPath()

void SoGLRenderAction::addDelayedPath

(

SoPath *

path

)

Adds a path to the list of paths to render after the current pass.

isRenderingDelayedPaths()

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.

handleTransparency()

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.

setCurPass()

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

getCurPass()

int SoGLRenderAction::getCurPass

(

void

)

const

Returns the number of the current rendering pass.

abortNow()

SbBool SoGLRenderAction::abortNow

(

void

)

Returns TRUE if the render action should abort now based on user callback.

See also

setAbortCallback()

setRenderingIsRemote()

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 displaylist 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()

getRenderingIsRemote()

SbBool SoGLRenderAction::getRenderingIsRemote

(

void

)

const

Returns whether or not the application is running remotely.

See also

setRenderingIsRemote()

invalidateState()

void SoGLRenderAction::invalidateState ( void  )

virtual

Invalidates the state, forcing it to be recreated at the next apply() invocation.

Reimplemented from SoAction.

addPreRenderCallback()

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().

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()

setSortedLayersNumPasses()

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.

getSortedLayersNumPasses()

int SoGLRenderAction::getSortedLayersNumPasses

(

void

)

const

Returns the number of passes to render when in SoGLRenderAction::SORTED_LAYERS_BLEND mode.

setSortedObjectOrderStrategy()

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

setDelayedObjDepthWrite()

void SoGLRenderAction::setDelayedObjDepthWrite

(

SbBool

write

)

Set whether depth buffer updates should be done when rendering delayed or sorted transparent objects.

Since

Coin 3.0

getDelayedObjDepthWrite()

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

isRenderingTranspPaths()

SbBool SoGLRenderAction::isRenderingTranspPaths

(

void

)

const

Returns TRUE if the action is currently rendering delayed or sorted transparent objects.

Since

Coin 3.0

isRenderingTranspBackfaces()

SbBool SoGLRenderAction::isRenderingTranspBackfaces

(

void

)

const

Returns TRUE if the action is currently rendering backfacing polygons in NONSOLID_SEPARATE_BACKFACE_PASS mode.

Since

Coin 3.0

beginTraversal()

void SoGLRenderAction::beginTraversal ( SoNode *  node )

protectedvirtual

This virtual method is called from SoAction::apply(), and is the entry point for the actual scenegraph 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 scenegraph traversal.

Reimplemented from SoAction.

endTraversal()

void SoGLRenderAction::endTraversal ( SoNode *  node )

protectedvirtual

This virtual method can be overridden to execute code after the scene graph traversal. Default method does nothing.

Reimplemented from SoAction.

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The documentation for this class was generated from the following files:

• SoGLRenderAction.h
• SoGLRenderAction.cpp