Coin

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¶

virtual SoType getTypeId (void) const

Returns the type identification of an object derived from a class inheriting SoBase. This is used for run-time type checking and 'downward' casting. SbViewVolume getViewVolume (const SbViewportRegion &vp, SbViewportRegion &resultvp, const SbMatrix &mm=SbMatrix::identity()) const

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)

virtual void viewBoundingBox (const SbBox3f &box, float aspect, float slack)=0

Static Public Member Functions¶

static SoType getClassTypeId (void)

static void initClass (void)

Public Attributes¶

SoSFEnum viewportMapping

SoSFVec3f position

SoSFRotation orientation

SoSFFloat aspectRatio

SoSFFloat nearDistance

SoSFFloat farDistance

SoSFFloat focalDistance

Protected Member Functions¶

virtual const SoFieldData * getFieldData (void) const

SoCamera (void)

virtual ~SoCamera ()

virtual void jitter (int numpasses, int curpass, const SbViewportRegion &vpreg, SbVec3f &jitteramount) const

Static Protected Member Functions¶

static const SoFieldData ** getFieldDataPtr (void)

Additional Inherited Members¶

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 if 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;
}

NB: The support for multiple cameras in Coin is limited, and problems with multiple cameras will be considered fixed on a case by case basis.

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.

Enumerator

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¶

SoType SoCamera::getTypeId (void) const [virtual]¶

Returns the type identification of an object derived from a class inheriting SoBase. This is used for run-time type checking and 'downward' casting. Usage example:

void foo(SoNode * node)
{
  if (node->getTypeId() == SoFile::getClassTypeId()) {
    SoFile * filenode = (SoFile *)node;  // safe downward cast, knows the type
  }
}

For application programmers wanting to extend the library with new nodes, engines, nodekits, draggers or others: 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 for instance Inventor/nodes/SoSubNode.h (SO_NODE_INIT_CLASS and SO_NODE_CONSTRUCTOR for node classes), Inventor/engines/SoSubEngine.h (for engine classes) and so on.

For more information on writing Coin extensions, see the class documentation of the toplevel superclasses for the various class groups.

Implements SoBase.

Reimplemented in SoFrustumCamera, SoOrthographicCamera, and SoPerspectiveCamera.

const SoFieldData * SoCamera::getFieldData (void) const [protected], [virtual]¶

Returns a pointer to the class-wide field data storage object for this instance. If no fields are present, returns NULL.

Reimplemented from SoFieldContainer.

Reimplemented in SoFrustumCamera, SoOrthographicCamera, and SoPerspectiveCamera.

SbViewVolume SoCamera::getViewVolume (const SbViewportRegion &vp, SbViewportRegion &resultvp, const SbMatrix &mm = SbMatrix::identity() ) const¶

Convenience method which returns the actual view volume used when rendering, adjusted for the current viewport mapping.

Supply the view's viewport in vp. If the viewport mapping is one of CROP_VIEWPORT_FILL_FRAME, CROP_VIEWPORT_LINE_FRAME or CROP_VIEWPORT_NO_FRAME, resultvp will be modified to contain the resulting viewport.

If you got any transformations in front of the camera, mm should contain this transformation.

Since:

Coin 4.0

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

void SoCamera::scaleHeight (floatscalefactor) [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 SoFrustumCamera, SoOrthographicCamera, and SoPerspectiveCamera.

SbViewVolume SoCamera::getViewVolume (floatuseaspectratio = 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 use getViewVolume(SbViewportRegion & vp, const SbMatrix & mm), or 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 the SoCamera::getView() source-code (private method) to see how this is done.

Implemented in  SoFrustumCamera, SoOrthographicCamera, and SoPerspectiveCamera.

void SoCamera::viewAll ( SoNode *constsceneroot, const SbViewportRegion &vpregion, const floatslack = 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.

void SoCamera::viewAll ( SoPath *constpath, const SbViewportRegion &vpregion, const floatslack = 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 ( StereoModemode)¶

Sets the stereo mode.

SoCamera::StereoMode SoCamera::getStereoMode (void) const¶

Returns the stereo mode.

void SoCamera::setStereoAdjustment (floatadjustment)¶

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) const¶

Returns the stereo adjustment.

See also:

setStereoAdjustment()

void SoCamera::setBalanceAdjustment (floatadjustment)¶

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) const¶

Returns the stereo balance adjustment.

See also:

setBalanceAdjustment()