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SoCamera.3coin2

NAME

SoCamera -

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.

SYNOPSIS

#include <Inventor/nodes/SoCamera.h>

Inherits SoNode.

Inherited by SoFrustumCamera, SoOrthographicCamera, and SoPerspectiveCamera.

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 audioRender (SoAudioRenderAction *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

static 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

Friends

class SoCameraP

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::ViewportMappingEnumerates the available possibilities for how the render frame should map the viewport.

enum SoCamera::StereoModeEnumerates the possible stereo modes.

Enumerator:

MONOSCOPIC

No stereo.

LEFT_VIEW

Left view.

RIGHT_VIEW

Right view.

Constructor & Destructor Documentation

SoCamera::SoCamera (void) [protected]Constructor.

References aspectRatio, farDistance, focalDistance, MONOSCOPIC, nearDistance, orientation, position, and viewportMapping.

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, SoPerspectiveCamera, and SoFrustumCamera.

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.

References SbVec3f::dot(), SbVec3f::normalize(), position, SoDebugError::postInfo(), and SbVec3f::setValue().

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 function is an extension for Coin, and it is not available in the original SGI Open Inventor v2.1 API.

References SbVec3f::normalize(), position, and SoDebugError::postInfo().

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, SoPerspectiveCamera, and SoFrustumCamera.

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;
   }
 
   .fi
 
 
 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, SoPerspectiveCamera, and SoFrustumCamera.
 
 Referenced by rayPick().
 

 

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(). A bounding sphere will be calculated from the scene bounding box, so the camera will 'view all' even when the scene is rotated, in any way.

The slack argument gives a multiplication factor to the distance the camera is supposed to move out from the sceneroot mid-point.

A value less than 1.0 for the slack argument will therefore cause the camera to come closer to the scene, a value of 1.0 will position the camera as exactly outside the scene bounding sphere, and a value larger than 1.0 will give 'extra slack' versus the scene bounding sphere.

References SoAction::apply(), aspectRatio, SoGetBoundingBoxAction::getBoundingBox(), SbBox3f::getMax(), SbBox3f::getMin(), SbViewportRegion::getViewportSize(), SbViewportRegion::getWindowSize(), SbBox3f::isEmpty(), SoDebugError::postInfo(), and 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().

References SoAction::apply(), aspectRatio, SoGetBoundingBoxAction::getBoundingBox(), SbBox3f::isEmpty(), and viewBoundingBox().

SbViewportRegion SoCamera::getViewportBounds (const SbViewportRegion & region) constBased in the SoCamera::viewportMapping setting, convert the values of region to the viewport region we will actually render into.

References aspectRatio, SbViewportRegion::getViewportAspectRatio(), SbViewportRegion::scaleHeight(), SbViewportRegion::scaleWidth(), and viewportMapping.

void SoCamera::setStereoMode (StereoMode mode)Sets the stereo mode.

SoCamera::StereoMode SoCamera::getStereoMode (void) constReturns the stereo mode.

void SoCamera::setStereoAdjustment (float adjustment)Sets the stereo adjustment. This is the distance between the left and right 'eye' when doing stereo rendering.

When doing stereo rendering, Coin will render two views, one for the left eye, and one for the right eye. The stereo adjustment is, a bit simplified, how much the camera is translated along the local X-axis between the left and the right view.

The default distance is 0.1, which is chosen since it's the approximate distance between the human eyes.

To create a nice looking and visible stereo effect, the application programmer will often have to adjust this value. If all you want to do is examine simple stand-alone 3D objects, it is possible to calculate a stereo offset based on the bounding box of the 3D model (or scale the model down to an appropriate size).

However, if you have a large scene, where you want to fly around in the scene, and see stereo on different objects as you approach them, you can't calculate the stereo offset based on the bounding box of the scene, but rather use a stereo offset based on the scale of the individual objects/details you want to examine.

Please note that it's important to set a sensible focal distance when doing stereo rendering. See setBalanceAdjustment() for information about how the focal distance affects the stereo rendering.

See also:

setBalanceAdjustment()

float SoCamera::getStereoAdjustment (void) constReturns the stereo adjustment.

See also:

setStereoAdjustment()

void SoCamera::setBalanceAdjustment (float adjustment)Sets the stereo balance adjustment. This is a factor that enables you to move the zero parallax plane. Geometry in front of the zero parallax plane will appear to be in front of the screen.

The balance adjustment is multiplied with the focal distance to find the zero parallax plane. The default value is 1.0, and the zero parallax plane is then at the focal point.

See also:

SoCamera::focalDistance

float SoCamera::getBalanceAdjustment (void) constReturns the stereo balance adjustment.

See also:

setBalanceAdjustment()

void SoCamera::doAction (SoAction * action) [virtual]This function performs the typical operation of a node for any action.

Reimplemented from SoNode.

References focalDistance, SoFieldContainer::get(), SbViewVolume::getDepth(), SbViewVolume::getHeight(), SbViewVolume::getMatrices(), SoAction::getState(), SbViewVolume::getWidth(), SbMatrix::identity(), SbMatrix::inverse(), SbMatrix::multRight(), SoFieldContainer::set(), and SbViewVolume::transform().

Referenced by callback(), getBoundingBox(), getPrimitiveCount(), and rayPick().

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.

References doAction().

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.

References SbVec3f::cross(), focalDistance, SbViewVolume::frustum(), SoFieldContainer::get(), SbViewVolume::getDepth(), SbViewVolume::getHeight(), SbViewVolume::getMatrices(), SbViewVolume::getNearDist(), SoGLRenderAction::getNumPasses(), SbViewVolume::getProjectionDirection(), SoAction::getState(), SbViewVolume::getViewUp(), SbViewVolume::getWidth(), SbMatrix::identity(), SbMatrix::inverse(), jitter(), LEFT_VIEW, MONOSCOPIC, SbMatrix::multRight(), SbVec3f::normalize(), SoFieldContainer::set(), SbMatrix::setTranslate(), and SbViewVolume::transform().

void SoCamera::audioRender (SoAudioRenderAction * action) [virtual]Action method for SoAudioRenderAction.

Does common processing for SoAudioRenderAction action instances.

Reimplemented from SoNode.

References SoFieldContainer::get(), SbViewVolume::getDepth(), SbViewVolume::getHeight(), SoAction::getState(), SbMatrix::getTransform(), SbVec3f::getValue(), SbViewVolume::getWidth(), SoField::isIgnored(), SoListenerOrientationElement::isSetByListener(), SoListenerPositionElement::isSetByListener(), orientation, position, SoDebugError::postInfo(), SoFieldContainer::set(), and SbViewVolume::transform().

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.

References doAction(), and SoAction::getState().

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.

References SoAction::getState(), and SoFieldContainer::set().

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.

References SoRayPickAction::computeWorldSpaceRay(), doAction(), SbViewVolume::getDepth(), SbViewVolume::getHeight(), getViewVolume(), and SbViewVolume::getWidth().

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.

References doAction().

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, SoPerspectiveCamera, and SoFrustumCamera.

Referenced by viewAll().

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.

References SbVec3f::getValue(), and SbViewportRegion::getViewportSizePixels().

Referenced by GLRender().

Member Data Documentation

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

Referenced by getViewportBounds(), and SoCamera().

SoSFVec3f SoCamera::positionCamera position. Defaults to <0,0,1>.

Referenced by audioRender(), SoPerspectiveCamera::getViewVolume(), SoOrthographicCamera::getViewVolume(), SoFrustumCamera::getViewVolume(), pointAt(), SoCamera(), SoPerspectiveCamera::viewBoundingBox(), SoOrthographicCamera::viewBoundingBox(), and SoFrustumCamera::viewBoundingBox().

SoSFRotation SoCamera::orientationCamera 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.

E.g., to rotate the camera to point along the X axis:

   mycamera->orientation.setValue(SbRotation(SbVec3f(0, 1, 0), M_PI / 2.0f));
 

For queries, e.g. to get the current 'up' and 'look at' vectors of the camera:

   SbRotation camrot = mycamera->orientation.getValue();
 
   SbVec3f upvec(0, 1, 0); // init to default up vector
   camrot.multVec(upvec, upvec);
 
   SbVec3f lookat(0, 0, -1); // init to default view direction vector
   camrot.multVec(lookat, lookat);
 

 

Referenced by audioRender(), SoPerspectiveCamera::getViewVolume(), SoOrthographicCamera::getViewVolume(), SoFrustumCamera::getViewVolume(), SoCamera(), SoPerspectiveCamera::viewBoundingBox(), SoOrthographicCamera::viewBoundingBox(), and SoFrustumCamera::viewBoundingBox().

SoSFFloat SoCamera::aspectRatioAspect ratio for the camera (i.e. width / height). Defaults to 1.0.

Referenced by getViewportBounds(), SoPerspectiveCamera::getViewVolume(), SoOrthographicCamera::getViewVolume(), SoCamera(), and viewAll().

SoSFFloat SoCamera::nearDistanceDistance 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

Referenced by SoPerspectiveCamera::getViewVolume(), SoOrthographicCamera::getViewVolume(), SoFrustumCamera::getViewVolume(), SoCamera(), SoPerspectiveCamera::viewBoundingBox(), SoOrthographicCamera::viewBoundingBox(), and SoFrustumCamera::viewBoundingBox().

SoSFFloat SoCamera::farDistanceDistance 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

Referenced by SoPerspectiveCamera::getViewVolume(), SoOrthographicCamera::getViewVolume(), SoFrustumCamera::getViewVolume(), SoCamera(), SoPerspectiveCamera::viewBoundingBox(), SoOrthographicCamera::viewBoundingBox(), and SoFrustumCamera::viewBoundingBox().

SoSFFloat SoCamera::focalDistanceDistance from camera position to center of scene.

Referenced by doAction(), GLRender(), SoCamera(), SoPerspectiveCamera::viewBoundingBox(), SoOrthographicCamera::viewBoundingBox(), and SoFrustumCamera::viewBoundingBox().

Author

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