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SoCamera Class Reference
[Nodes]

The SoCamera class is the abstract base class for camera definition nodes. More...

#include <Inventor/nodes/SoCamera.h>

Inheritance diagram for SoCamera:

SoNode SoFieldContainer SoBase SoOrthographicCamera SoPerspectiveCamera List of all members.

Public Types

enum  ViewportMapping {
  CROP_VIEWPORT_FILL_FRAME, CROP_VIEWPORT_LINE_FRAME, CROP_VIEWPORT_NO_FRAME, ADJUST_CAMERA,
  LEAVE_ALONE
}
enum  StereoMode { MONOSCOPIC, LEFT_VIEW, RIGHT_VIEW }

Public Member Functions

void pointAt (const SbVec3f &targetpoint)
void pointAt (const SbVec3f &targetpoint, const SbVec3f &upvector)
virtual void scaleHeight (float scalefactor)=0
virtual SbViewVolume getViewVolume (float useaspectratio=0.0f) const =0
void viewAll (SoNode *const sceneroot, const SbViewportRegion &vpregion, const float slack=1.0f)
void viewAll (SoPath *const path, const SbViewportRegion &vpregion, const float slack=1.0f)
SbViewportRegion getViewportBounds (const SbViewportRegion &region) const
void setStereoMode (StereoMode mode)
StereoMode getStereoMode (void) const
void setStereoAdjustment (float adjustment)
float getStereoAdjustment (void) const
void setBalanceAdjustment (float adjustment)
float getBalanceAdjustment (void) const
virtual void doAction (SoAction *action)
virtual void callback (SoCallbackAction *action)
virtual void GLRender (SoGLRenderAction *action)
virtual void getBoundingBox (SoGetBoundingBoxAction *action)
virtual void handleEvent (SoHandleEventAction *action)
virtual void rayPick (SoRayPickAction *action)
virtual void getPrimitiveCount (SoGetPrimitiveCountAction *action)

Static Public Member Functions

void initClass (void)

Public Attributes

SoSFEnum viewportMapping
SoSFVec3f position
SoSFRotation orientation
SoSFFloat aspectRatio
SoSFFloat nearDistance
SoSFFloat farDistance
SoSFFloat focalDistance

Protected Member Functions

 SoCamera (void)
virtual ~SoCamera ()
virtual void viewBoundingBox (const SbBox3f &box, float aspect, float slack)=0
virtual void jitter (int numpasses, int curpass, const SbViewportRegion &vpreg, SbVec3f &jitteramount) const

Detailed Description

The SoCamera class is the abstract base class for camera definition nodes.

To be able to view a scene, one needs to have a camera in the scene graph. A camera node will set up the projection and viewing matrices for rendering of the geometry in the scene.

This node just defines the abstract interface by collecting common fields that all camera type nodes needs. Use the non-abstract camera node subclasses within a scene graph. The ones that are default part of the Coin library are SoPerspectiveCamera and SoOrthographicCamera, which uses the two different projections given by their name.

Note that the viewer components of the GUI glue libraries of Coin (SoXt, SoQt, SoWin, etc) will automatically insert a camera into a scene graph is none has been defined.

It is possible to have more than one camera in a scene graph. One common trick is for instance to use a second camera to display static geometry or overlay geometry (e.g. for head-up displays ("HUD")), as shown by this example code:

#include <Inventor/Qt/SoQt.h> #include <Inventor/Qt/viewers/SoQtExaminerViewer.h> #include <Inventor/nodes/SoNodes.h> int main(int argc, char ** argv) { QWidget * mainwin = SoQt::init(argv[0]); SoSeparator * root = new SoSeparator; root->ref(); // Adds a camera and a red cone. The first camera found in the // scene graph by the SoQtExaminerViewer will be picked up and // initialized automatically. root->addChild(new SoPerspectiveCamera); SoMaterial * material = new SoMaterial; material->diffuseColor.setValue(1.0, 0.0, 0.0); root->addChild(material); root->addChild(new SoCone); // Set up a second camera for the remaining geometry. This camera // will not be picked up and influenced by the viewer, so the // geometry will be kept static. SoPerspectiveCamera * pcam = new SoPerspectiveCamera; pcam->position = SbVec3f(0, 0, 5); pcam->nearDistance = 0.1; pcam->farDistance = 10; root->addChild(pcam); // Adds a green cone to demonstrate static geometry. SoMaterial * greenmaterial = new SoMaterial; greenmaterial->diffuseColor.setValue(0, 1.0, 0.0); root->addChild(greenmaterial); root->addChild(new SoCone); SoQtExaminerViewer * viewer = new SoQtExaminerViewer(mainwin); viewer->setSceneGraph(root); viewer->show(); SoQt::show(mainwin); SoQt::mainLoop(); delete viewer; root->unref(); return 0; }


Member Enumeration Documentation

enum SoCamera::ViewportMapping
 

Enumerates the available possibilities for how the render frame should map the viewport.

enum SoCamera::StereoMode
 

Enumerates the possible stereo modes.

Enumeration values:
MONOSCOPIC  No stereo.
LEFT_VIEW  Left view.
RIGHT_VIEW  Right view.


Constructor & Destructor Documentation

SoCamera::SoCamera void   )  [protected]
 

Constructor.

SoCamera::~SoCamera  )  [protected, virtual]
 

Destructor.


Member Function Documentation

void SoCamera::initClass void   )  [static]
 

Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system.

Reimplemented from SoNode.

Reimplemented in SoOrthographicCamera, and SoPerspectiveCamera.

void SoCamera::pointAt const SbVec3f targetpoint  ) 
 

Reorients the camera so that it points towards targetpoint. The positive y-axis is used as the up vector of the camera, unless the new camera direction is parallel to this axis, in which case the positive z-axis will be used instead.

void SoCamera::pointAt const SbVec3f targetpoint,
const SbVec3f upvector
 

Reorients the camera so that it points towards targetpoint, using upvector as the camera up vector.

This method is an extension versus the Open Inventor API.

void SoCamera::scaleHeight float  scalefactor  )  [pure virtual]
 

Sets a scalefactor for the height of the camera viewport. What "viewport height" means exactly in this context depends on the camera model. See documentation in subclasses.

Implemented in SoOrthographicCamera, and SoPerspectiveCamera.

SbViewVolume SoCamera::getViewVolume float  useaspectratio = 0.0f  )  const [pure virtual]
 

Returns total view volume covered by the camera under the current settings.

This view volume is not adjusted to account for viewport mapping. If you want the same view volume as the one used during rendering, you should do something like this:

SbViewVolume vv; float aspectratio = myviewport.getViewportAspectRatio(); switch (camera->viewportMapping.getValue()) { case SoCamera::CROP_VIEWPORT_FILL_FRAME: case SoCamera::CROP_VIEWPORT_LINE_FRAME: case SoCamera::CROP_VIEWPORT_NO_FRAME: vv = camera->getViewVolume(0.0f); break; case SoCamera::ADJUST_CAMERA: vv = camera->getViewVolume(aspectratio); if (aspectratio < 1.0f) vv.scale(1.0f / aspectratio); break; case SoCamera::LEAVE_ALONE: vv = camera->getViewVolume(0.0f); break; default: assert(0 && "unknown viewport mapping"); break; }

Also, for the CROPPED viewport mappings, the viewport might be changed if the viewport aspect ratio is not equal to the camera aspect ratio. See SoCamera::getView() to see how this is done.

Implemented in SoOrthographicCamera, and SoPerspectiveCamera.

void SoCamera::viewAll SoNode *const  sceneroot,
const SbViewportRegion vpregion,
const float  slack = 1.0f
 

Position the camera so that all geometry of the scene from sceneroot is contained in the view volume of the camera, while keeping the camera orientation constant.

Finds the bounding box of the scene and calls SoCamera::viewBoundingBox().

void SoCamera::viewAll SoPath *const  path,
const SbViewportRegion vpregion,
const float  slack = 1.0f
 

Position the camera so all geometry of the scene in path is contained in the view volume of the camera.

Finds the bounding box of the scene and calls SoCamera::viewBoundingBox().

SbViewportRegion SoCamera::getViewportBounds const SbViewportRegion region  )  const
 

Based in the SoCamera::viewportMapping setting, convert the values of region to the viewport region we will actually render into.

void SoCamera::setStereoMode StereoMode  mode  ) 
 

Sets the stereo mode.

SoCamera::StereoMode SoCamera::getStereoMode void   )  const
 

Returns the stereo mode.

void SoCamera::setStereoAdjustment float  adjustment  ) 
 

Sets the stereo adjustment.

float SoCamera::getStereoAdjustment void   )  const
 

Returns the stereo adjustment.

void SoCamera::setBalanceAdjustment float  adjustment  ) 
 

Sets the stereo balance adjustment.

float SoCamera::getBalanceAdjustment void   )  const
 

Returns the stereo balance adjustment.

void SoCamera::doAction SoAction action  )  [virtual]
 

This function performs the typical operation of a node for any action.

Reimplemented from SoNode.

void SoCamera::callback SoCallbackAction action  )  [virtual]
 

Action method for SoCallbackAction.

Simply updates the state according to how the node behaves for the render action, so the application programmer can use the SoCallbackAction for extracting information about the scene graph.

Reimplemented from SoNode.

void SoCamera::GLRender SoGLRenderAction action  )  [virtual]
 

Action method for the SoGLRenderAction.

This is called during rendering traversals. Nodes influencing the rendering state in any way or who wants to throw geometry primitives at OpenGL overrides this method.

Reimplemented from SoNode.

void SoCamera::getBoundingBox SoGetBoundingBoxAction action  )  [virtual]
 

Action method for the SoGetBoundingBoxAction.

Calculates bounding box and center coordinates for node and modifies the values of the action to encompass the bounding box for this node and to shift the center point for the scene more towards the one for this node.

Nodes influencing how geometry nodes calculates their bounding box also overrides this method to change the relevant state variables.

Reimplemented from SoNode.

void SoCamera::handleEvent SoHandleEventAction action  )  [virtual]
 

Picking actions can be triggered during handle event action traversal, and to do picking we need to know the camera state.

See also:
SoCamera::rayPick()

Reimplemented from SoNode.

void SoCamera::rayPick SoRayPickAction action  )  [virtual]
 

Action method for SoRayPickAction.

Checks the ray specification of the action and tests for intersection with the data of the node.

Nodes influencing relevant state variables for how picking is done also overrides this method.

Reimplemented from SoNode.

void SoCamera::getPrimitiveCount SoGetPrimitiveCountAction action  )  [virtual]
 

Action method for the SoGetPrimitiveCountAction.

Calculates the number of triangle, line segment and point primitives for the node and adds these to the counters of the action.

Nodes influencing how geometry nodes calculates their primitive count also overrides this method to change the relevant state variables.

Reimplemented from SoNode.

void SoCamera::viewBoundingBox const SbBox3f box,
float  aspect,
float  slack
[protected, pure virtual]
 

Convenience method for setting up the camera definition to cover the given bounding box with the given aspect ratio. Multiplies the exact dimensions with a slack factor to have some space between the rendered model and the borders of the rendering area.

If you define your own camera node class, be aware that this method should not set the orientation field of the camera, only the position, focal distance and near and far clipping planes.

Implemented in SoOrthographicCamera, and SoPerspectiveCamera.

void SoCamera::jitter int  numpasses,
int  curpass,
const SbViewportRegion vpreg,
SbVec3f jitteramount
const [protected, virtual]
 

"Jitter" the camera according to the current rendering pass (curpass), to get an antialiased rendering of the scene when doing multipass rendering.


Member Data Documentation

SoSFEnum SoCamera::viewportMapping
 

Set up how the render frame should map the viewport. The default is SoCamera::ADJUST_CAMERA.

SoSFVec3f SoCamera::position
 

Camera position. Defaults to <0,0,1>.

SoSFRotation SoCamera::orientation
 

Camera orientation specified as a rotation value from the default orientation where the camera is pointing along the negative z-axis, with "up" along the positive y-axis.

SoSFFloat SoCamera::aspectRatio
 

Aspect ratio for the camera (i.e. width / height). Defaults to 1.0.

SoSFFloat SoCamera::nearDistance
 

Distance from camera position to the near clipping plane in the camera's view volume.

Default value is 1.0. Value must be larger than 0.0, or it will not be possible to construct a valid viewing volume (for perspective rendering, at least).

If you use one of the viewer components from the So[Xt|Qt|Win|Gtk] GUI libraries provided by Systems in Motion, they will automatically update this value for the scene camera according to the scene bounding box. Ditto for the far clipping plane.

See also:
SoCamera::farDistance

SoSFFloat SoCamera::farDistance
 

Distance from camera position to the far clipping plane in the camera's view volume.

Default value is 10.0. Must be larger than the SoCamera::nearDistance value, or it will not be possible to construct a valid viewing volume.

Note that the range [nearDistance, farDistance] decides the dynamic range of the Z-buffer in the underlying polygon-rendering rasterizer. What this means is that if the near and far clipping planes of the camera are wide apart, the possibility of visual artifacts will increase. The artifacts will manifest themselves in the form of flickering of primitives close in depth.

It is therefore a good idea to keep the near and far clipping planes of your camera(s) as closely fitted around the geometry of the scene graph as possible.

See also:
SoCamera::nearDistance, SoPolygonOffset

SoSFFloat SoCamera::focalDistance
 

Distance from camera position to center of scene.


The documentation for this class was generated from the following files:
Generated on Tue Jul 27 23:53:03 2004 for Coin by doxygen 1.3.7