OpenSceneGraph/examples/osgdepthpartition/DepthPartitionNode.cpp

#include "DepthPartitionNode.h"
#include <osgUtil/CullVisitor>

#define CURRENT_CLASS DepthPartitionNode
CURRENT_CLASS::CURRENT_CLASS()
{
	_distAccumulator = new DistanceAccumulator;
	init();
}

CURRENT_CLASS::CURRENT_CLASS(const CURRENT_CLASS& dpn, const osg::CopyOp& copyop)
	: _active(dpn._active),
	  _renderOrder(dpn._renderOrder),
	  _clearColorBuffer(dpn._clearColorBuffer)
{
	_distAccumulator = new DistanceAccumulator;
	_numCameras = 0;
}

CURRENT_CLASS::~CURRENT_CLASS() {}

void CURRENT_CLASS::init()
{
	_active = true;
	_numCameras = 0;
	setCullingActive(false);
	_renderOrder = osg::CameraNode::POST_RENDER;
	_clearColorBuffer = true;
}

void CURRENT_CLASS::setActive(bool active)
{
	if(_active == active) return;
	_active = active;
}

void CURRENT_CLASS::setClearColorBuffer(bool clear)
{
	_clearColorBuffer = clear;

	// Update the render order for the first CameraNode if it exists
	if(!_cameraList.empty())
	{
	  if(clear) 
	    _cameraList[0]->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	  else  
	    _cameraList[0]->setClearMask(GL_DEPTH_BUFFER_BIT);
	}
}

void CURRENT_CLASS::setRenderOrder(osg::CameraNode::RenderOrder order)
{
	_renderOrder = order;

	// Update the render order for existing CameraNodes
	unsigned int numCameras = _cameraList.size();
	for(unsigned int i = 0; i < numCameras; i++)
	{
	  _cameraList[i]->setRenderOrder(_renderOrder);
	}
}

void CURRENT_CLASS::traverse(osg::NodeVisitor &nv)
{
	// If the scene hasn't been defined then don't do anything
	unsigned int numChildren = _children.size();
	if(numChildren == 0) return;

	// If the node is not active then don't analyze it
	if(!_active)
	{
	  // Traverse the graph as usual
	  Group::traverse(nv);
	  return;
	}

	// If the visitor is not a cull visitor, pass it directly onto the scene.
	osgUtil::CullVisitor* cv = dynamic_cast<osgUtil::CullVisitor*>(&nv);
	if(!cv) 
	{ 
	  Group::traverse(nv);
	  return; 
	}

	// We are in the cull traversal, so first collect information on the
	// current modelview and projection matrices and viewport.
	osg::RefMatrix& modelview = cv->getModelViewMatrix();
	osg::RefMatrix& projection = cv->getProjectionMatrix();
	osg::Viewport* viewport = cv->getViewport();

	// Prepare for scene traversal.
	_distAccumulator->setMatrices(modelview, projection);
	_distAccumulator->setNearFarRatio(cv->getNearFarRatio());
	_distAccumulator->reset();

	// Step 1: Traverse the children, collecting the near/far distances.
	unsigned int i;
	for(i = 0; i < numChildren; i++)
	{
	  _children[i]->accept(*(_distAccumulator.get()));
	}

	// Step 2: Compute the near and far distances for every CameraNode that
	// should be used to render the scene.
	_distAccumulator->computeCameraPairs();

	// Step 3: Create the CameraNodes, and add them as children.
	DistanceAccumulator::PairList& camPairs = _distAccumulator->getCameraPairs();
	_numCameras = camPairs.size(); // Get the number of cameras

	// Create the CameraNodes, and add them as children.
	if(_numCameras > 0)
	{
	  osg::CameraNode *currCam;
	  DistanceAccumulator::DistancePair currPair;

	  for(i = 0; i < _numCameras; i++)
	  {
	    // Create the camera, and clamp it's projection matrix
	    currPair = camPairs[i];  // (near,far) pair for current camera
	    currCam = createOrReuseCamera(projection, currPair.first, 
	                                  currPair.second, i);

	    // Set the modelview matrix and viewport of the camera
	    currCam->setViewMatrix(modelview);
	    currCam->setViewport(viewport);

	    // Redirect the CullVisitor to the current camera
	    currCam->accept(nv);
	  }

	  // Set the clear color for the first camera
	  _cameraList[0]->setClearColor(cv->getRenderStage()->getClearColor());
	}
}

bool CURRENT_CLASS::addChild(osg::Node *child)
{
	return insertChild(_children.size(), child);
}

bool CURRENT_CLASS::insertChild(unsigned int index, osg::Node *child)
{
	if(!Group::insertChild(index, child)) return false; // Insert child

	// Insert child into each CameraNode
	unsigned int totalCameras = _cameraList.size();
	for(unsigned int i = 0; i < totalCameras; i++)
	{
	  _cameraList[i]->insertChild(index, child);
	}
	return true;
}

bool CURRENT_CLASS::removeChild(osg::Node *child)
{
	return Group::removeChild(child);
}

bool CURRENT_CLASS::removeChild(unsigned int pos, unsigned int numRemove)
{
	if(!Group::removeChild(pos, numRemove)) return false; // Remove child

	// Remove child from each CameraNode
	unsigned int totalCameras = _cameraList.size();
	for(unsigned int i = 0; i < totalCameras; i++)
	{
	  _cameraList[i]->removeChild(pos, numRemove);
	}
	return true;
}

bool CURRENT_CLASS::setChild(unsigned int i, osg::Node *node)
{
	if(!Group::setChild(i, node)) return false; // Set child

	// Set child for each CameraNode
	unsigned int totalCameras = _cameraList.size();
	for(unsigned int i = 0; i < totalCameras; i++)
	{
	  _cameraList[i]->setChild(i, node);
	}
	return true;
}

osg::CameraNode* CURRENT_CLASS::createOrReuseCamera(const osg::Matrix& proj, 
                            double near, double far, const unsigned int &camNum)
{
	if(_cameraList.size() <= camNum) _cameraList.resize(camNum+1);
	osg::CameraNode *camera = _cameraList[camNum].get();
	
	if(!camera) // Create a new CameraNode
	{
	  camera = new osg::CameraNode;
	  camera->setCullingActive(false);
	  camera->setRenderOrder(_renderOrder);
	  camera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);

	  // We will compute the near/far planes ourselves
	  camera->setComputeNearFarMode(osg::CullSettings::DO_NOT_COMPUTE_NEAR_FAR);
	  camera->setCullingMode(osg::CullSettings::ENABLE_ALL_CULLING);

	  if(camNum == 0 && _clearColorBuffer)
	    camera->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	  else
	    camera->setClearMask(GL_DEPTH_BUFFER_BIT);

	  // Add our children to the new CameraNode's children
	  unsigned int numChildren = _children.size();
	  for(unsigned int i = 0; i < numChildren; i++)
	  {
	    camera->addChild(_children[i].get());
	  }

	  _cameraList[camNum] = camera;
	}

	osg::Matrixd &projection = camera->getProjectionMatrix();
	projection = proj;

	// Slightly inflate the near & far planes to avoid objects at the
	// extremes being clipped out.
	near *= 0.999;
	far *= 1.001;

	// Clamp the projection matrix z values to the range (near, far)
	double epsilon = 1.0e-6;
	if(fabs(projection(0,3)) < epsilon &&
	   fabs(projection(1,3)) < epsilon &&
	   fabs(projection(2,3)) < epsilon ) // Projection is Orthographic
	{
	  epsilon = -1.0/(far - near); // Used as a temp variable
	  projection(2,2) = 2.0*epsilon;
	  projection(3,2) = (far + near)*epsilon;
	}
	else // Projection is Perspective
	{
	  double trans_near = (-near*projection(2,2) + projection(3,2)) /
	                      (-near*projection(2,3) + projection(3,3));
	  double trans_far = (-far*projection(2,2) + projection(3,2)) /
	                     (-far*projection(2,3) + projection(3,3));
	  double ratio = fabs(2.0/(trans_near - trans_far));
	  double center = -0.5*(trans_near + trans_far);

	  projection.postMult(osg::Matrixd(1.0, 0.0, 0.0, 0.0,
	                                   0.0, 1.0, 0.0, 0.0,
	 			           0.0, 0.0, ratio, 0.0,
					   0.0, 0.0, center*ratio, 1.0));
	}

	return camera;
}
#undef CURRENT_CLASS