Open Inventor Release 2024.1.1
 
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SoOffscreenRenderArea Class Reference

Render to an off-screen buffer for printing or generating textures. More...

#include <Inventor/SoOffscreenRenderArea.h>

+ Inheritance diagram for SoOffscreenRenderArea:

Classes

struct  EventArg
 Event that can be sent to the application for each tile rendered. More...
 

Public Types

enum  OutputFormat {
  RGB ,
  RGBA
}
 Describes the format of the rendering output. More...
 
- Public Types inherited from SiRenderArea
enum  ClearPolicy {
  NONE ,
  COLORBUFFER ,
  DEPTHBUFFER ,
  COLORBUFFER_AND_DEPTHBUFFER
}
 Policy values to clear color and depth buffers beforing rendering. More...
 
enum  RenderStatus {
  ABORTED ,
  INTERACTIVE ,
  STILL
}
 Returned by the render method. More...
 

Public Member Functions

 SoOffscreenRenderArea ()
 Default constructor.
 
 SoOffscreenRenderArea (SoGLContext *glContex)
 Builds a new offscreen render area by sharing the given SoGlContext.
 
 SoOffscreenRenderArea (SoRenderAreaCore *renderAreaCore)
 Builds a new offscreen render area by using the given renderAreaCore.
 
 ~SoOffscreenRenderArea ()
 Destructor.
 
virtual void setSceneGraph (SoNode *newScene)
 Defines the scene graph which will be traversed for rendering.
 
virtual SoNodegetSceneGraph () const
 
void setViewportRegion (const SbViewportRegion &newRegion)
 Defines viewport region (within the image) to use for rendering.
 
SbViewportRegion getViewportRegion () const
 
virtual void setTransparencyType (SoGLRenderAction::TransparencyType type)
 Defines the algorithm for rendering transparent objects.
 
virtual SoGLRenderAction::TransparencyType getTransparencyType () const
 
SoSceneManagergetSceneManager () const
 Returns the encapsulated scene manager.
 
bool renderToFile (const SbString &filename, OutputFormat outputFormat=RGB) const
 Render the given scene graph and save the result in the given file.
 
bool renderToBuffer (SoBufferObject *buffer, OutputFormat outputFormat=RGB) const
 Render the given scene graph and save the result in the given buffer.
 
void setTile (SbVec2i32 size, int numEdgePixels)
 Defines the maximum sub-image (tile) size for rendering and the number of pixels on the border of each sub-image that are not written on the final image.
 
SbVec2i32 getTileSize () const
 
int getNumEdgePixels () const
 
virtual ClearPolicy getClearPolicy () const
 
virtual void setClearPolicy (ClearPolicy policy)
 Defines the color buffer and depth buffer clear policy.
 
virtual void setClearColor (const SbColorRGBA &color)
 Defines the RGBA value used when the color buffer is cleared.
 
virtual SbColorRGBA getClearColor () const
 
virtual void setClearDepth (float depth)
 Defines the depth value used when the depth buffer is cleared.
 
virtual float getClearDepth () const
 
virtual void setSize (const SbVec2i32 &size)
 Defines the image size to use for rendering.
 
virtual SbVec2i32 getSize () const
 
virtual void setGLRenderAction (SoGLRenderAction *glAction)
 Defines the render action used for rendering.
 
virtual SoGLRenderActiongetGLRenderAction () const
 Returns the render action used for rendering.
 
virtual SbEventHandler< RenderEventArg & > & onStartRender ()
 Returns the event handler that raises when a new render starts.
 
virtual void setAntialiasingMode (SoSceneManager::AntialiasingMode mode)
 Define the antialiasing mode.
 
virtual SoSceneManager::AntialiasingMode getAntialiasingMode () const
 
virtual void setAntialiasingQuality (float quality)
 Define the antialiasing quality value.
 
virtual float getAntialiasingQuality () const
 
virtual RenderStatus render ()
 Calling the render() method is useless and does nothing.
 
- Public Member Functions inherited from SoRefCounter
void ref () const
 Adds a reference to an instance.
 
void unref () const
 Removes a reference from an instance.
 
void unrefNoDelete () const
 unrefNoDelete() should be called when it is desired to decrement the reference count, but not delete the instance if this brings the reference count to zero.
 
int getRefCount () const
 Returns current reference count.
 
void lock () const
 lock this instance.
 
void unlock () const
 unlock this instance.
 

Static Public Member Functions

static SbVec2i32 getMaxTileSize ()
 Gets the maximum subimage (tile) size for rendering.
 

Public Attributes

SbEventHandler< EventArg & > onTileRendered
 Event raised when a tile has been rendered.
 

Detailed Description

Render to an off-screen buffer for printing or generating textures.

This class is used to render a scene graph and to write the the result into a file or a buffer.

This is not a screen capture class. The specified scene graph is rendered to generate an image. This allows generation of images larger (higher resolution) than the user's screen and/or using different (e.g. higher quality) rendering parameters. The offscreen rendering may take more or less time than the same rendering on screen.

The renderer can render very large images because it is able to render the scene as multiple "tiles" and assemble the tiles into a complete image. Of course this requires multiple render traversals of the specified scene graph (one for each tile).

Rendering a "snapshot":

Your application may want to render the same image that the user sees on the screen. There are several things to consider. First, the scene graph given to the renderer must include the camera node that the viewer is using. If the application allows the viewer to create a camera automatically, the scene graph returned by the viewer's getSceneGraph() method does not include the camera. It's always safer to get the SoSceneManager object then get the scene graph. Second, some rendering options are set on the viewer object, not in the scene graph. These options, which include background color and transparency mode, must be explicitly queried from the viewer and set on the renderer object.

Notes & Limitations:

  • The default tile size is set to the maximum viewport size supported by the hardware (GL_MAX_VIEWPORT_DIMS), which means that tiling will be enabled only when large viewport sizes are requested.
  • When tiling is enabled, the elements SoViewportRegionElement, SoLogicalViewportElement and SoModifyViewVolumeElement are set with different values for each tile, which means that scenegraphs that manage sub-viewports will need to take these elements into account in order for the final rendering to be correct.
  • Maximum output image size is 25000 x 25000 pixels.

EXAMPLE

Member Enumeration Documentation

◆ OutputFormat

Describes the format of the rendering output.

Enumerator
RGB 

3 components: red, green and blue

RGBA 

4 components: red, green, blue and alpha

Definition at line 230 of file SoOffscreenRenderArea.h.

Constructor & Destructor Documentation

◆ SoOffscreenRenderArea() [1/3]

SoOffscreenRenderArea::SoOffscreenRenderArea ( )

Default constructor.

NOTE: An internally created SoGLContext will be shared with the current context or an existing one if possible. In order to have control over the SoGLContext sharing, use the alternate constructor.

◆ SoOffscreenRenderArea() [2/3]

SoOffscreenRenderArea::SoOffscreenRenderArea ( SoGLContext glContex)

Builds a new offscreen render area by sharing the given SoGlContext.

◆ SoOffscreenRenderArea() [3/3]

SoOffscreenRenderArea::SoOffscreenRenderArea ( SoRenderAreaCore renderAreaCore)

Builds a new offscreen render area by using the given renderAreaCore.

Any following call to setSceneGraph will change the scene graph used by this instance.

◆ ~SoOffscreenRenderArea()

SoOffscreenRenderArea::~SoOffscreenRenderArea ( )

Destructor.

Member Function Documentation

◆ getAntialiasingMode()

virtual SoSceneManager::AntialiasingMode SoOffscreenRenderArea::getAntialiasingMode ( ) const
virtual

◆ getAntialiasingQuality()

virtual float SoOffscreenRenderArea::getAntialiasingQuality ( ) const
virtual

◆ getClearColor()

virtual SbColorRGBA SoOffscreenRenderArea::getClearColor ( ) const
virtual
See also
setClearColor().

Implements SiRenderArea.

◆ getClearDepth()

virtual float SoOffscreenRenderArea::getClearDepth ( ) const
virtual
See also
setClearDepth().

Implements SiRenderArea.

◆ getClearPolicy()

virtual ClearPolicy SoOffscreenRenderArea::getClearPolicy ( ) const
virtual
See also
setClearPolicy().

Implements SiRenderArea.

◆ getGLRenderAction()

virtual SoGLRenderAction * SoOffscreenRenderArea::getGLRenderAction ( ) const
virtual

Returns the render action used for rendering.

◆ getMaxTileSize()

static SbVec2i32 SoOffscreenRenderArea::getMaxTileSize ( )
static

Gets the maximum subimage (tile) size for rendering.

◆ getNumEdgePixels()

int SoOffscreenRenderArea::getNumEdgePixels ( ) const
See also
setTile().

◆ getSceneGraph()

virtual SoNode * SoOffscreenRenderArea::getSceneGraph ( ) const
virtual
See also
setSceneGraph().

Implements SiRenderArea.

◆ getSceneManager()

SoSceneManager * SoOffscreenRenderArea::getSceneManager ( ) const

Returns the encapsulated scene manager.

◆ getSize()

virtual SbVec2i32 SoOffscreenRenderArea::getSize ( ) const
virtual
See also
setSize().

Implements SiRenderArea.

◆ getTileSize()

SbVec2i32 SoOffscreenRenderArea::getTileSize ( ) const
See also
setTile().

◆ getTransparencyType()

virtual SoGLRenderAction::TransparencyType SoOffscreenRenderArea::getTransparencyType ( ) const
virtual

◆ getViewportRegion()

SbViewportRegion SoOffscreenRenderArea::getViewportRegion ( ) const

◆ onStartRender()

virtual SbEventHandler< RenderEventArg & > & SoOffscreenRenderArea::onStartRender ( )
virtual

Returns the event handler that raises when a new render starts.

Implements SiRenderArea.

◆ render()

virtual RenderStatus SoOffscreenRenderArea::render ( )
virtual

Calling the render() method is useless and does nothing.

This function returns always ABORTED.

Implements SiRenderArea.

◆ renderToBuffer()

bool SoOffscreenRenderArea::renderToBuffer ( SoBufferObject buffer,
OutputFormat  outputFormat = RGB 
) const

Render the given scene graph and save the result in the given buffer.

The buffer is resized if its current size is not equal to the the necessary size to store the rendering result.

If your application needs more control over creation of an output file, the SoBufferObject can be converted into an SbRasterImage using the appropriate constructor. Once instantiated, the SbRasterImage can be passed as a parameter to the write function of any class inheriting from SoRasterImageRW (SoJPEGImageRW for example to generate a JPEG file).

Parameters
bufferstores the result of the rendering.
outputFormatdefines which components to write to the output. If set to RGBA, the alpha component of the rendering is also written to the buffer.

◆ renderToFile()

bool SoOffscreenRenderArea::renderToFile ( const SbString filename,
OutputFormat  outputFormat = RGB 
) const

Render the given scene graph and save the result in the given file.

The format of the generated image is chosen automatically according to the file extension. Returns true if successful.

If your application needs more control over creation of the file, please see the renderToBuffer() method.

Supported file types are:

extension file (case insensitive) raster image type Alpha Component Support
.bmp Windows bitmap YES
.dds DirectDraw surface YES
.gif Graphics Interchange Format YES
.hdr hdr NO
.jp2, .j2c, .j2k, .jpc, .jpx, .ecw, .ecwp jpeg 2000 YES
.jpg, .jpeg, .jif, .jfif Joint Photographic Experts Group NO
.pgx pgx NO
.png Portable Network Graphics YES
.pnm .pgm .ppm pnm YES
.ps PostScript NO
.rgb .sgi sgi YES
.ras sun YES
.tif .tiff Tagged Image File Format YES

Parameters
filenamepath and name of the image file to be generated. If the file extension is not one of the above type, no file is generated.
outputFormatdefines which components to write to the output. If set to RGBA, the alpha component of the rendering is also written to the file. However if the targeted file type does not support alpha component, the file will be generated with RGB components only. See the 3rd column of the above table.

◆ setAntialiasingMode()

virtual void SoOffscreenRenderArea::setAntialiasingMode ( SoSceneManager::AntialiasingMode  mode)
virtual

Define the antialiasing mode.

Parameters
modeThe antialiasing algorithm. Default is NO_ANTIALIASING which turns off antialiasing.

Implements SiRenderAreaAntialiasing.

◆ setAntialiasingQuality()

virtual void SoOffscreenRenderArea::setAntialiasingQuality ( float  quality)
virtual

Define the antialiasing quality value.

Parameters
qualityThe quality is a factor in the range [0.0,1.0].
Default is 0.0. The value 0.0 turns off antialiasing.

Implements SiRenderAreaAntialiasing.

◆ setClearColor()

virtual void SoOffscreenRenderArea::setClearColor ( const SbColorRGBA color)
virtual

Defines the RGBA value used when the color buffer is cleared.

Default is transparent black (0,0,0,0). This is the value used to clear the color buffer when renderToFile() or renderToBuffer() are called with setClearPolicy() method set to COLORBUFFER or COLORBUFFER_AND_DEPTHBUFFER . See also setClearPolicy.

Parameters
colorRGBA value used to clear the color buffer.

Implements SiRenderArea.

◆ setClearDepth()

virtual void SoOffscreenRenderArea::setClearDepth ( float  depth)
virtual

Defines the depth value used when the depth buffer is cleared.

The default value is 1. This is the value used to clear the depth buffer when renderToFile() or renderToBuffer() are called with setClearPolicy() method set to DEPTHBUFFER or COLORBUFFER_AND_DEPTHBUFFER . See also setClearPolicy.

Parameters
depthvalue used to clear the depth buffer. Value is clamped to the range [0,1].

Implements SiRenderArea.

◆ setClearPolicy()

virtual void SoOffscreenRenderArea::setClearPolicy ( ClearPolicy  policy)
virtual

Defines the color buffer and depth buffer clear policy.

Default value is ClearPolicy::COLORBUFFER_AND_DEPTHBUFFER. Effects such as motion blur can be created by disabling clear color buffer or depth buffer. Use enum ClearPolicy. See also setClearColor and setClearDepth.

Parameters
policycolor buffer and depth buffer clear policy.

Implements SiRenderArea.

◆ setGLRenderAction()

virtual void SoOffscreenRenderArea::setGLRenderAction ( SoGLRenderAction glAction)
virtual

Defines the render action used for rendering.

◆ setSceneGraph()

virtual void SoOffscreenRenderArea::setSceneGraph ( SoNode newScene)
virtual

Defines the scene graph which will be traversed for rendering.

Implements SiRenderArea.

◆ setSize()

virtual void SoOffscreenRenderArea::setSize ( const SbVec2i32 size)
virtual

Defines the image size to use for rendering.

Implements SiRenderArea.

◆ setTile()

void SoOffscreenRenderArea::setTile ( SbVec2i32  size,
int  numEdgePixels 
)

Defines the maximum sub-image (tile) size for rendering and the number of pixels on the border of each sub-image that are not written on the final image.

The default tile size is set to the maximum viewport size supported by the hardware (GL_MAX_VIEWPORT_DIMS) and can be queried using the getMaxTileSize() method.

The default value for the number of edge pixels is 2 pixels.

Edge pixels are usually required to avoid visual "artifacts" at the subimage boundaries. One source of artifacts is that when OpenGL clips lines, it draws a line between the points where the line exits and re-enters the visible region. This additional segment is not part of the actual geometry. A two pixel border will hide this undesired segment unless the line width is greater than two, in which case you may need to specify a larger number of edge pixels.

Parameters
sizeis dimension of the tile.
numEdgePixelsis the number of pixels on the edge of the tile which will not be included in the final image.

◆ setTransparencyType()

virtual void SoOffscreenRenderArea::setTransparencyType ( SoGLRenderAction::TransparencyType  type)
virtual

Defines the algorithm for rendering transparent objects.

Default is NO_SORT. See SoGLRenderAction for possible transparency types. See also SoGLRenderAction::TransparencyType.

Note: When using OPAQUE_FIRST, SORTED_OBJECT or SORTED_PIXEL transparency, the depth buffer is not updated (depth buffer writes are disabled) while rendering transparent objects. As a result complex 3D shapes may not be rendered correctly.

Implements SiRenderAreaTransparency.

◆ setViewportRegion()

void SoOffscreenRenderArea::setViewportRegion ( const SbViewportRegion newRegion)

Defines viewport region (within the image) to use for rendering.

Member Data Documentation

◆ onTileRendered

SbEventHandler<EventArg&> SoOffscreenRenderArea::onTileRendered

Event raised when a tile has been rendered.

Definition at line 479 of file SoOffscreenRenderArea.h.


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