SceneGraph.cpp

Go to the documentation of this file.

// Copyright (C) 2005 Dave Griffiths
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

#include "SceneGraph.h"
#include "PolyPrimitive.h"

using namespace Fluxus;

SceneGraph::SceneGraph()
{
    // need to reset to having a root node present
    Clear();
}

SceneGraph::~SceneGraph()
{
}

void SceneGraph::Render(Mode rendermode)
{
    //RenderWalk((SceneNode*)m_Root,0);

    glGetFloatv(GL_MODELVIEW_MATRIX,m_TopTransform.arr());  

    // render all the children of the root
    for (vector<Node*>::iterator i=m_Root->Children.begin(); i!=m_Root->Children.end(); ++i)
    {
        RenderWalk((SceneNode*)*i,0,rendermode);
    }
    
    // now render the depth sorted primitives:
    m_DepthSorter.Render();
    m_DepthSorter.Clear();
}

void SceneGraph::RenderWalk(SceneNode *node, int depth, Mode rendermode)
{
    // max gl matrix stack is 32 
    /*if (depth>=30)
    {
        Trace::Stream<<"SceneGraph::RenderWalk: max stack reached"<<endl;
        return;
    }*/
    
    if (node->Prim->Hidden()) return;
    if (rendermode==SELECT && !node->Prim->IsSelectable()) return;
    
    
    dMatrix parent;
    // see if we need the parent (result of all the parents) transform
    if (node->Prim->GetState()->Hints & HINT_DEPTH_SORT)
    {
        glGetFloatv(GL_MODELVIEW_MATRIX,parent.arr());
    }
    
    glPushMatrix();     
    
    // if we are a lazy parent then we need to ignore 
    // the effects of the heirachical transform - we 
    // treat their transform as a world space one
    if (node->Prim->GetState()->Hints & HINT_LAZY_PARENT)
    {
        glLoadMatrixf(m_TopTransform.arr());
    }
    
    node->Prim->ApplyState();
    
    //if (!FrustumClip(node))
    {
        if (node->Prim->GetState()->Hints & HINT_DEPTH_SORT)
        {
            // render it later, and after depth sorting
            m_DepthSorter.Add(parent,node->Prim,node->ID);
        }
        else
        {
            glPushName(node->ID);
            node->Prim->Prerender();
            node->Prim->Render();
            glPopName();
        }

        depth++;

        for (vector<Node*>::iterator i=node->Children.begin(); i!=node->Children.end(); ++i)
        {
            RenderWalk((SceneNode*)*i,depth,rendermode);
        }
    }
    glPopMatrix();
    
    if (node->Prim->GetState()->Hints & HINT_CAST_SHADOW)
    {
        m_ShadowVolumeGen.Generate(node->Prim);
    }
}

// this is working the wrong way - need to write proper 
// frustum culling by building planes from the camera 
// frustum and checking is any points are inside
bool SceneGraph::FrustumClip(SceneNode *node)
{
    // do the frustum clip
    dBoundingBox box; 
    GetBoundingBox(node,box);
    dMatrix mat,proj;
    glGetFloatv(GL_MODELVIEW_MATRIX,mat.arr());
    glGetFloatv(GL_PROJECTION_MATRIX,proj.arr());
    mat=proj*mat;
    char cs = 0xff;
    
    dVector p = mat.transform_persp(box.min);
    CohenSutherland(p,cs);
    p=mat.transform_persp(box.max);
    CohenSutherland(p,cs);
    p=mat.transform_persp(dVector(box.min.x,box.min.y,box.max.z));
    CohenSutherland(p,cs);
    p=mat.transform_persp(dVector(box.min.x,box.max.y,box.min.z));
    CohenSutherland(p,cs);
    p=mat.transform_persp(dVector(box.min.x,box.max.y,box.max.z));
    CohenSutherland(p,cs);
    p=mat.transform_persp(dVector(box.max.x,box.min.y,box.min.z));
    CohenSutherland(p,cs);
    p=mat.transform_persp(dVector(box.max.x,box.min.y,box.max.z));
    CohenSutherland(p,cs);
    p=mat.transform_persp(dVector(box.max.x,box.max.y,box.min.z));
    CohenSutherland(p,cs);

    return cs!=0;
}

void SceneGraph::CohenSutherland(const dVector &p, char &cs)
{
    char t=0;
    if (p.z>0.0f) // in front of the camera
    {
        if (p.x>1)       t |= 0x01;
        else if (p.x<-1) t |= 0x02;
        if (p.y>1)       t |= 0x04;
        else if (p.y<-1) t |= 0x08;
    }
    else // behind the camera
    {
        if (p.x<-1)    t |= 0x01;
        else if (p.x>1) t |= 0x02;
        if (p.y<-1)     t |= 0x04;
        else if (p.y>1) t |= 0x08;
    }
    cs&=t;
}

void SceneGraph::Detach(SceneNode *node)
{
    if (node->Parent!=m_Root)
    {
        // keep the concatenated transform
        node->Prim->GetState()->Transform=GetGlobalTransform(node);
        
        // move node to the root
        node->Parent->RemoveChild(node->ID);
        m_Root->Children.push_back(node);
        node->Parent=m_Root;
    }
}

dMatrix SceneGraph::GetGlobalTransform(const SceneNode *node) const
{
    dMatrix Mat,Ret;
    
    list<const SceneNode*> Path;
    
    const SceneNode* current=node;
    
    // iterate back up the tree storing parents...
    // lazy parent objects are treated as non-heirachical,
    // so we can stop if we find one of them - and
    // use it's transform as world space
    bool foundlazy=false;
    while(current!=NULL && !foundlazy)
    {
        if (current && current->Prim) 
        {
            Path.push_front(current);
            foundlazy = current->Prim->GetState()->Hints & HINT_LAZY_PARENT;
        }
        current=(const SceneNode*)current->Parent;
    }
        
    // concatenate the matrices together to get the global
    for (list<const SceneNode*>::iterator i=Path.begin(); i!=Path.end(); ++i)
    {
        Mat*=(*i)->Prim->GetState()->Transform;
    }

    return Mat;
}

void SceneGraph::GetBoundingBox(SceneNode *node, dBoundingBox &result)
{
    dMatrix mat;
    GetBoundingBox(node, mat, result);
}

void SceneGraph::GetBoundingBox(SceneNode *node, dMatrix mat, dBoundingBox &result)
{
    if (!node) return;
    
    if (node->Prim)
    {
        dVector point(0,0,0);
        dBoundingBox bbox=node->Prim->GetBoundingBox();
        bbox.min=mat.transform(bbox.min);
        bbox.max=mat.transform(bbox.max);
        result.expand(bbox);
        mat*=node->Prim->GetState()->Transform;
    }

    for (vector<Node*>::iterator i=node->Children.begin(); i!=node->Children.end(); ++i)
    {
        GetBoundingBox((SceneNode*)*i,mat,result);
    }
}

void SceneGraph::GetNodes(const Node *node, vector<const SceneNode*> &nodes) const
{       
    nodes.push_back(static_cast<const SceneNode*>(node));
    
    for (vector<Node*>::const_iterator i=node->Children.begin(); 
            i!=node->Children.end(); i++)
    {
        GetNodes(*i,nodes);
    }
}

void SceneGraph::GetConnections(const Node *node, vector<pair<const SceneNode*,const SceneNode*> > &connections) const
{       
    for (vector<Node*>::const_iterator i=node->Children.begin(); 
            i!=node->Children.end(); i++)
    {
        connections.push_back(pair<const SceneNode *,const SceneNode *>
                                (static_cast<const SceneNode*>(node),
                                 static_cast<const SceneNode*>(*i)));
        GetConnections(*i,connections);
    }
}
void SceneGraph::Clear()
{
    Tree::Clear();
    SceneNode *root = new SceneNode(NULL);
    AddNode(0,root);
}

---