ossimActiveEdgeTable Class Reference

#include <ossimActiveEdgeTable.h>

Public Member Functions
	ossimActiveEdgeTable ()
void	addPolygon (const ossimPolygon &polygon)
const std::list< ossimActiveEdgeTableNode > &	getActiveList () const
ossim_int32	getCurrentScanLine () const
ossim_int32	getYShift () const
void	initializeActiveList ()
void	updateActiveEdges ()
void	mergeCurrentScanLine ()
void	printActiveEdgeList () const

Protected Member Functions
void	createTable (const ossimPolygon &polygon)
void	addEdgeToTable (const ossimActiveEdgeTableNode &edge, ossim_int32 scanLine)

Protected Attributes
std::vector< std::list< ossimActiveEdgeTableNode > >	theTable
std::list< ossimActiveEdgeTableNode >	theActiveList
ossimIrect	theBoundingRect
ossimIpt	theRectOrigin
ossim_int32	theLastScanLine
ossim_int32	theCurrentScanLine

Friends
class	ossimActiveEdgeTableHelper

Detailed Description

This class is used in fast efficient scanliine rasterization. It will take a polygon and insert it into the table sorted by y's

Definition at line 64 of file ossimActiveEdgeTable.h.

Constructor & Destructor Documentation

ossimActiveEdgeTable()

ossimActiveEdgeTable::ossimActiveEdgeTable

(

)

Definition at line 18 of file ossimActiveEdgeTable.cpp.

{
   
}

Member Function Documentation

addEdgeToTable()

void ossimActiveEdgeTable::addEdgeToTable ( const ossimActiveEdgeTableNode &  edge, ossim_int32  scanLine  )

protected

Definition at line 87 of file ossimActiveEdgeTable.cpp.

{
   theTable[scanLine].push_back(edge);
}

addPolygon()

void ossimActiveEdgeTable::addPolygon

(

const ossimPolygon &

polygon

)

Currently will only work on a single polygon. If you call this twice it currently will use the last called polygon and will wipe out the previous one.

Note: this is used for scanline rasterization and will round to integer values all vertices as they are initially added to the Active Edge Table.

Definition at line 23 of file ossimActiveEdgeTable.cpp.

References ossimPolygon::getVertexCount(), x, and y.

{
   createTable(polygon);
   if(theTable.size())
   {
      ossim_int32 iNextY, iY;
      ossimActiveEdgeTableNode edge;
      ossim_uint32 numPts = polygon.getVertexCount();
      theLastScanLine = 0;
      
      for (ossim_uint32 i=0; i<numPts; ++i)
      {
         // CURRENT EDGE IS FROM polygon[i] to polygon[(i+1)%numPts]
         int iNext = (i+1)%numPts;  // INDEX FOR SECOND EDGE VERTEX
         iNextY = ossim::round<ossim_int32>(polygon[iNext].y-theRectOrigin.y);
         iY = ossim::round<ossim_int32>(polygon[i].y-theRectOrigin.y);
         int dy = (iNextY - iY);
         if (dy != 0)   // ADD ONLY IF EDGE NOT HORIZONTAL
         {
            if (dy> 0)  // local max
            {
               double m = (polygon[iNext].x-polygon[i].x)/
                          (polygon[iNext].y-polygon[i].y);
                                 
               edge = ossimActiveEdgeTableNode(iNextY+1,
                                               m,
                                               polygon[i].x);

               addEdgeToTable(edge, iY);
                                               
            }
            else         // local min so 
            {
               double m = (polygon[i].x-polygon[iNext].x)/
                          (polygon[i].y-polygon[iNext].y);

               edge = ossimActiveEdgeTableNode(iY,
                                               m,
                                               polygon[iNext].x);
               
               addEdgeToTable(edge, iNextY);
            }
            
         }
      }
   }
}

createTable()

void ossimActiveEdgeTable::createTable ( const ossimPolygon &  polygon )

protected

Definition at line 71 of file ossimActiveEdgeTable.cpp.

References ossimPolygon::getBoundingRect(), and ossimPolygon::getVertexCount().

{
   theBoundingRect.makeNan();
   theRectOrigin.makeNan();
   if(polygon.getVertexCount() >2)
   {
      theTable.clear();
      polygon.getBoundingRect(theBoundingRect);
      if(!theBoundingRect.hasNans())
      {
         theTable.resize(theBoundingRect.height()+1);
         theRectOrigin = theBoundingRect.ul();
      }
   }   
}

getActiveList()

const std::list<ossimActiveEdgeTableNode>& ossimActiveEdgeTable::getActiveList

(

)

const

getCurrentScanLine()

ossim_int32 ossimActiveEdgeTable::getCurrentScanLine ( ) const

inline

Definition at line 85 of file ossimActiveEdgeTable.h.

References theCurrentScanLine.

Referenced by ossimActiveEdgeTableHelper::getCurrentScanLine(), and ossimActiveEdgeTableHelper::getNextLineSegment().

      {
         return theCurrentScanLine;
      }

getYShift()

ossim_int32 ossimActiveEdgeTable::getYShift ( ) const

inline

Definition at line 89 of file ossimActiveEdgeTable.h.

References theRectOrigin, and ossimIpt::y.

Referenced by ossimActiveEdgeTableHelper::getYShift().

      {
         return theRectOrigin.y;
      }

initializeActiveList()

void ossimActiveEdgeTable::initializeActiveList

(

)

Definition at line 93 of file ossimActiveEdgeTable.cpp.

References size.

Referenced by ossimActiveEdgeTableHelper::advanceScanLine().

{
   int i = 0;
   for(i=0;i<(int)theTable.size();++i)
   {
      if(theTable[i].size())
      {
         theActiveList = theTable[i];
         theTable[i].clear();
         theCurrentScanLine = i;
         theActiveList.sort();
         return;
      }
   }
}

mergeCurrentScanLine()

void ossimActiveEdgeTable::mergeCurrentScanLine

(

)

Definition at line 128 of file ossimActiveEdgeTable.cpp.

References size.

Referenced by ossimActiveEdgeTableHelper::advanceScanLine().

{
   if((theCurrentScanLine < (int)theTable.size())&&
      theTable[theCurrentScanLine].size())
   {
      theTable[theCurrentScanLine].sort();
      theActiveList.merge(theTable[theCurrentScanLine]);
      theActiveList.sort();

      theTable[theCurrentScanLine].clear();
   }
}

printActiveEdgeList()

void ossimActiveEdgeTable::printActiveEdgeList

(

)

const

Definition at line 141 of file ossimActiveEdgeTable.cpp.

References ossimNotify(), and ossimNotifyLevel_INFO.

{
   copy(theActiveList.begin(),
        theActiveList.end(),
        ostream_iterator<ossimActiveEdgeTableNode>(ossimNotify(ossimNotifyLevel_INFO) << "->"));
   ossimNotify(ossimNotifyLevel_INFO) << "NULL\n";
}

updateActiveEdges()

void ossimActiveEdgeTable::updateActiveEdges

(

)

Definition at line 109 of file ossimActiveEdgeTable.cpp.

Referenced by ossimActiveEdgeTableHelper::advanceScanLine().

{
   std::list<ossimActiveEdgeTableNode>::iterator current = theActiveList.begin();

   while(current != theActiveList.end())
   {
      (*current).theCurrentX += (*current).theSlope;

      if((*current).theMaxY == theCurrentScanLine)
      {
         current = theActiveList.erase(current);
      }
      else
      {
         ++current;
      }
   }
};

Friends And Related Function Documentation

ossimActiveEdgeTableHelper

friend class ossimActiveEdgeTableHelper

friend

Definition at line 67 of file ossimActiveEdgeTable.h.

Member Data Documentation

theActiveList

std::list<ossimActiveEdgeTableNode> ossimActiveEdgeTable::theActiveList

protected

Definition at line 101 of file ossimActiveEdgeTable.h.

Referenced by ossimActiveEdgeTableHelper::advanceScanLine(), and ossimActiveEdgeTableHelper::getNextLineSegment().

theBoundingRect

ossimIrect ossimActiveEdgeTable::theBoundingRect

protected

Used in computing the number of scanlines of the passed in polygon and is also used to shift the y's relative to 0,0

Definition at line 110 of file ossimActiveEdgeTable.h.

theCurrentScanLine

ossim_int32 ossimActiveEdgeTable::theCurrentScanLine

protected

Definition at line 113 of file ossimActiveEdgeTable.h.

Referenced by ossimActiveEdgeTableHelper::advanceScanLine(), and getCurrentScanLine().

theLastScanLine

ossim_int32 ossimActiveEdgeTable::theLastScanLine

protected

Definition at line 112 of file ossimActiveEdgeTable.h.

theRectOrigin

ossimIpt ossimActiveEdgeTable::theRectOrigin

protected

Definition at line 111 of file ossimActiveEdgeTable.h.

Referenced by getYShift().

theTable

std::vector< std::list<ossimActiveEdgeTableNode> > ossimActiveEdgeTable::theTable

protected

Definition at line 100 of file ossimActiveEdgeTable.h.

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The documentation for this class was generated from the following files:

• ossimActiveEdgeTable.h
• ossimActiveEdgeTable.cpp